The Vortec swap nightmare saga continues.................

I figured I would post a new thread rather than revive an old thread so that people don't have to sift through dozens of posts to get down to the nitty gritty. For those just tuning in the important info is; '89 Firebird Formula 5.0 L03 TBI w/700R4. Replaced 305 with used L31 shortblock and cylinder heads from different L31. New HV oil pump, GMPP single roller chain, 7qt deep sump oil pan, custom fabbed front half of exhaust from original 2" outlet manifolds to 3" midpipe and flowmaster muffler. Edelbrock Performer RPM 4bbl intake and Holley 4bbl-TBI adapter and reused ALL other hardware from the 305. Base fuel pressure ~30psi due to idiot mechanic (me) installing way too much of a fuel pump long time ago. Later replaced 1228746 ECM with 16197427 PCM. So, in the last episode I realized that I had installed the incorrect dizzy gear and that the RPM signal to PCM was fluctuating and determined that it was time for a new dizzy.......

Fast forward to the present and I have made progress and also determined that I am destined to rebuild this car piece-by-piece wether I want to or not. I finally got a new GM distributor and also a new Accel cap & rotor kit and installed them. The GM dizzy comes with a cap and rotor installed, but I simply prefer the Accel parts as they are more robust and just as affordable at ~$25 for the set. I trimmed and re-routed the existing Accel 8mm spiral-core plug wires as they are in ok shape and I found a spare set of terminals for the dizzy end of the wires in the basement. I also replaced the low-mileage plugs as there was some fouling from a rapidly progresing misfire. After all said repairs were made I restarted the car and found that I had cured one ailment only to discover another. The old dizzy was having issues that I believe to be rooted in the aftermarket ICM. The new dizzy did clear up a lot of isues and also required a remap of the ignition timing after trial and error showed that the old map parformed very differently with a new and "proper" dizzy was installed.

The problem was, however, that upon fixing one issue the next issue only stood-out even more. Cutting to the chase, I'll leave out the boring bits and get right to the isue. After some driving and tuning, I discovered the MAP sensor to be going bad. I always monitor it in my logs and quickly noticed that it would not register numerically lower than 38kpa anymore. I instantly recognized this as a problem knowing full-well that at idle in park it usually reads closer to 30 and while decelerating it will drop into the teens under the right circumstances. I quickly sourced a known-good used late model MAP sensor and connector and installed it directly to the TBI unit with a short section of hose. Upon startup I knew that the issue was resolved before connecting the laptop. That led, however, to yet another issue..........

This time the issue is mostly programming related. I had been logging and using the VE correction spreadsheet as the MAP sennsor was going bad (unknowingly of course) and had been tuning IN a terrible deadspot. Once I had replaced the MAP sensor, the deadspot only became more pronounced and it took a little watching to spot the issue. So, to correct the issue enough to drive the car I had to throw in the old VE tables and start from there. The car drives pretty good now, but there seems to be something wrong with my DE and DFCO settings. What is happening is that while decelerating the BLM will continue to drop until it switches into DFCO. Then, upon exiting DFCO, the current BLM cell will be all jacked-up for lack of a better term and the car will lean out to the point of stuttering until the BLM counts back up into the proper range. I can bypass the deadspot by nailing the throttle and entering PE mode, but this is obviously not a solution.

So, I will attach my latest BIN and XDL for any to take a peek at. The VE tables are way off at this point because I reverted back to some starter tables after replacing the MAP sensor and using the VE correction spreadsheed will make the problem worse due to the current issue. Using these crude VE tables makes the car drive the best at the moment until I fix the DE/DFCO issue so take note of that while looking things over. The spark tables are pretty close at the moment and the knock counts are due to several different verified mechanical noises (non internal-engine damage related noises) at the moment so the knock retard has been disabled temporarily. I think there's more, but gotta go for now. Thanks in advance for taking the time to read through this post and reply.

EDIT: All of my recent log files are too large to upload so I will need to make a shorter drive and upload that file.

XDL file size has been increased. But a shorter log with issue is always easier to help with.

Welcome to my world! Try tuning a vehicle that has MULTIPLE mechanical issues... :laugh: I've honestly only done one in 2 years that did not have at least one issue! It was for a tech/owner of a shop.

Something that may be needed at this point is a new bin to start with. We sometimes change so many things that it is impossible to tune out what we tuned in, or something bad happened to bin? I've found compare difference to undefined items? Just a thought that has worked for me. Fueling was off due to MAP sensor, spark was off due to aftermarket EST/ICM. Possible 1000s of changes to bin. See where this is going?

But this stands out from what you said.

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The VE tables are way off at this point because

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Everything fuel related is an adjustment from the VE table. So if it is not right then neither is the adjustments like DEFCO, DECEL, AE, PE, etc.... You've got a combination engine, wet intake that is aftermarket for a carb, which is probably not an issue but could complicate one. For instance can't seem to get tune right? First more fuel, then less fuel? Well did you adjust fuel after a long idle or after a WOT run? WOT run would be a fairly dry intake where after a long idle would be wet spots.

Other then making an engine run till fully warmed up, then driving a little with a WOT run, I don't even bother to log data or look at wide band. Data is wrong! Then disconnect power to ECM to clear learn. Then start to get VE in order from data. I've just recently found this trick to save hours if not days of chasing my tail. Once VE is in order most other issues go away like your DFCO. If VE is right then it will run just as good without O2 sensor because fueling is correct.

HTH!

Well, the real problem here is the combination of parts as you said. I have basically created a one-of-a-kind franken-vortec (speaking in terms of mixing parts) that I have no known good pool of data to draw from. I also suspect that my unique and excessive fuel pressure is creating fueling inconsistencies that are just complicating matters. As far as my VE corrections go, this is how I was using the spreadsheet. I would log a drive that usually began recording after the car was warmed up and would still provide ~45 min worth of recording time. In TPv5 the data history tables populate as you record or playback and you can select running average, which I did based on the wording of the VE spreadsheet. I then copied and pasted to and from the spreadsheet as instructed. Using the running average option will do as implied and average the value of each used BLM cell over the course of however much data you run through it. Since the cells that count down while decelerating are the same cells used when reapplying the throttle, those cells would have a low BLM average because of the time spent off of the throttle. If you enter that value and compensate the VE table accordingly then you end up with a very low VE value in that cell so when you actually need the fuel with open throttle the BPW starts out very low and must slowly climb as the PCM detects an insanely lean o2 signal and slowly counts back up the BLM value. What you end up with is an EXTREMELY lean condition upon reapplying the accelerator after a couple of seconds of decel. The car will buck until the PCM can compensate and add more fuel. Living in a tourist town with lots of stop and go traffic creates a very unpleasant and also detrimental driving experience.

For the record, this issue began before the distributor change and possibly before the MAP sensor began to malfunction. I do not recall any particular event that spurred the issue and it began randomly during a drive home one day after the majority of the drive was over. I also agree that it may be time to start with a fresh bin as I have found that sometimes parts of the bin mysteriously get corrupted after thousands of tweaks and saves and transfers etc..... The issue here is that it seems for some unknown reason the PCM is not entering DE mode so while decelerating it sees that the o2 readings are going rich and instead of going into DE it simply begins lowering the fuel trims for the current cells. It does enter DFCO as you can feel it, but it appears that the BLM will still drop. This is why the BLM's are all over and I haven't wanted to modify the VE tables yet as while on the throttle the BLM's go high to correct the lean condition. I could be way off here with my assumptions, but this is far past the point that normal diagnostics go for a dealer tech such as myself. Especially considering that my training is continually focused on new and emerging technology and as EFI designs age the knowledge, support, and amount of vehicles returning for repairs diminishes. For example, I have never used my timing light on a customer vehicle and my distributor wrench doesn't see much more use. It has also been over a year since I have used a Tech 1 scanner either and The Tech 2 doesn't work on many new vehicles.

All the more reaon to start with fresh bin, rough in your Vortec head timing tables, smooth out the VE, check/uncheck what is required and start to tune.

What exactly is your fuel pressure nowadays? I thought we got this back to a realistic number awhile ago? If still super high there may be so many changes needed to compenste it's not worth the effort to tune, espaecailly if that much fuel is not needed.

45 minute logs are skewed data for tuning. BLM learn has taken away the adjustments your trying to make. I can't believe how many hours and days I've wasted with this method over the years. Try this with a fresh bin, I'd really like to see a tech with tuning experiance try my shortcut. EGR, DFCO, PE, Air divertor off. Warm up vehicle and drive, do a WOT run, just a little. Park, disconnect power to ECM, start vehicle and when goes closed loop record data, 5 minutes tops, make adjustments, disconnect power, rinse and repeat. I like to do this with 3-4 TPS% runs to rough in a VE table, then smooth it out and go back to a longer log. You'll notice then if you look at low and high they will be close together, why take an average of 108 BLM and 172 BLM to tune? Which one is right? Since I started this I can get a VE table accurate for a stock, mild or built motor in order within an hour or so. Will run CL or OL just as well, same day...

Not at home to look at disassembly but there are generally settings for locking out BLM during decel, DFCO, or for resetting after WOT or large throttle changes. Old ways still work... limit INT and BLM range to prevent excessive corrections from affecting VE tuning. What about your vehicle other than fuel pressure is radically different from Vortec TBI Van cal?

BLM issue you talk about is also part of $58 and is very difficult to tune out in that cal. Trick I use is to try and tailor AE to deliver slight extra shot of fuel after decel conditions. Have to work carefully with MAP and TPS AE to make this work and it never works as well as it should because stock $58 just doesn't provide enough control over AE. But the strategy should work better in the 7427 cals as there are more AE parameters to work with IIRC.

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Originally Posted by 1project2many

Not at home to look at disassembly but there are generally settings for locking out BLM during decel, DFCO, or for resetting after WOT or large throttle changes. Old ways still work... limit INT and BLM range to prevent excessive corrections from affecting VE tuning. What about your vehicle other than fuel pressure is radically different from Vortec TBI Van cal?

BLM issue you talk about is also part of $58 and is very difficult to tune out in that cal. Trick I use is to try and tailor AE to deliver slight extra shot of fuel after decel conditions. Have to work carefully with MAP and TPS AE to make this work and it never works as well as it should because stock $58 just doesn't provide enough control over AE. But the strategy should work better in the 7427 cals as there are more AE parameters to work with IIRC.

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The timing tables are copied and slightly modified from the BJYL 350 TBI 700R4 BIN that I downloaded from the ECM info section and are a lot more aggressive than stock BJYL and other TBI BINs. Since the true VE tables will be drastically different from the typical TBI BINs due to the fuel pressure. I had actually widened the BLM range which may be worsening the situiation unintentionally. There are more AE parameters in the $OD mask than in the $61 for sure and probably more than the $58 as well. I had added more shot and a longer time of shot on DFCO exit, but had also changed something else in the BIN that made the car barely driveable so I just went back to a previous BIN and tuned from there leaving those values alone. As we speak, I am searching for the most economical MPFI manifold solution along with the best value headers to balance out the entire setup a little better and also deal with the probable injector consistency issue from running excessive fuel pressure. I think that a lot of my tuning issues are due to the injectors and the pressure they've been running on for the last few years. At this point I want to keep the car driving ok, but don't want to waste too much time tuning on the current TBI setup as I'm dying to ditch it ASAP. Once I get the hardware combo finalized and can get the engine running properly I'm wanting to switch back over to running ethanol blends as the sheer smoothness and noticeable torque increases get to be just as addictive as drinking alcohol is.

Just a quick note on the current setup.. The exhaust manifolds were intended to be a very short term solution as I ran into financial problems right in the middle of the swap and just needed to make the car driveable. The intake setup as it is currently configured was not intended to be used much longer either. I've since had major financial problems that have limited me to barely being able to keep up with maintenance so I have long passed the amount of time I had planned on using this configuration. I am now in the position to be able to swap to a sensibly priced exhaust and induction setup that will compliment the L31 longblock. So, the bottom line is that I am fully aware that I have had so many issues with this setup due to it being a sad combination of thrown-together mis-matched parts that are fairly aged as well.

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Since the true VE tables will be drastically different from the typical TBI BINs due to the fuel pressure.

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With a specific induction system, changing fuel pressure should not require major changes inthe VE table. Volumetric efficiency represents the engine's ability to move air and is not based on the type of injector or the amount of fuel it delivers.* Injector specific values should be correct such as AE pulses, DE reduction, minimum PW, voltage correction, minimum asynch pulse, quasi asynch enable values. These values are designed to account for a specific injector's behavior. I recognize that getting these values correct can take a long time and that often the corrections find their way into the VE table instead but it is important to remember how the VE is intended to be used and to treat it accordingly.

* Wet flow manifolds will tend to have reduced VE compared to dry flow systems especially at low rpm as expanding fuel in the manifold displaces available oxygen.

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Originally Posted by 1project2many

With a specific induction system, changing fuel pressure should not require major changes inthe VE table. Volumetric efficiency represents the engine's ability to move air and is not based on the type of injector or the amount of fuel it delivers.* Injector specific values should be correct such as AE pulses, DE reduction, minimum PW, voltage correction, minimum asynch pulse, quasi asynch enable values. These values are designed to account for a specific injector's behavior. I recognize that getting these values correct can take a long time and that often the corrections find their way into the VE table instead but it is important to remember how the VE is intended to be used and to treat it accordingly.

* Wet flow manifolds will tend to have reduced VE compared to dry flow systems especially at low rpm as expanding fuel in the manifold displaces available oxygen.

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That makes sense and I had not thought of any of that. I had convinced myself that the VE tables would be so different due to the limitations of the '746 ecm and the alterations I had to make to account for fuel pressure and also when tuning for E85 as the majority of my tuning experience has been tuning for E85 fuel as it does "behave" differently than gas. Gotta run for now.

I think I'd try setting the '427 PCM for Open Loop and tune / correct the VE Tables using a WBO2 sensor. Once I got somewhere close with the Open Loop tuning, I'd enable Closed Loop but I'd disable the BLM Update and continue tuning / correcting the VE Tables using a WBO2. Then I'd enable the BLM Update and keep a close eye on the BLM averages. I've seen where BLM averages and WBO2 data do not match, so in that case disable BLM Update.

dave w

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Originally Posted by dave w

I'd enable Closed Loop but I'd disable the BLM Update and continue tuning
dave w

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D'oh!
Like disconnecting the battery? Man that has saved me so much time...

I agree with Dave. Although there is more than one way to skin this cat, the goal is to tune steady state first then transients. Disabling closed loop, EGR, DFCO, and other functions mentioned by Mark above is a way to prevent transient corrections from affecting your steady state tables, which are the basis for the entire tune.

At times I've favored disconnecting the battery but there are plenty of times when I don't bother. I think there's a correlation between ecm family or ecm number and whether or not this is really helpful. I am firmly convinced C3 tuning can be finished quicker if the battery is disconnected. P4, not so much. And I have nowhere near enough experience with the 7427 and cousins to tell.

with C3, it's almost a necessity if you don't lock the BLM min/max to 128.

with P4, either send a mode 4 command to clear out the learned BLMs or set the BLM min and max to 128.

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Originally Posted by RobertISaar

with P4, either send a mode 4 command to clear out the learned BLMs or set the BLM min and max to 128.

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I need to learn these mode 4 commands...

they're different for every application, but almost all P4 and P6/P66 units allow datalink control over outputs and a couple of internal functions, like BLM and IAC reset, forced open loop or closed loop fueling, etc...

Now your really pushing my buttons! :thumbsup:

I have to say that disabling closed loop and dfco and such (no egr valve or provisions on the intake) were where I thought I was heading as well. One major issue that I have always faced is simply the amount of time I have available to tune, drive and log, review log and tune, and repeat. Since I do not have an emulator and over half of my commute is on a busy section of interstate, I can only stop during each trip and make changes if the car is undriveable. I also have little chance to make good WOT runs that span widely through the RPM range and collect data. So, I only get to try 1-2 chips a day and that I can try and when I find something that seems to run ok I may go a couple days before messing with it. That all equates into a long and drawn out process especially after spending months working on a tune for the original ecm and then swapping to an entirely different ecm and basically starting over from scratch. But, I have learned a lot and slowly upgraded and repaired things along the way. I also have recently been approved for a permanent vacation by my employer so I will be putting a lot of effort into re-routing my commute to a much closer destination. I'm not really physically capable of retaining gainful employment as a flat-rate technician anymore so I may also be permanently relocating my toolboxes to my basement. Most importantly, I have a little time to dedicate to sorting out some of these issues as well as figuring out a few key things regarding how to properly and efficiently tune something a little farther from a stock setup than previously. I appreciate the input and will post updates as I go, BUT I still plan to settle on a MPFI induction solution and install a decent set of headers as soon as I can decide on shortys or long tubes. A wideband is something that I have tried to work around for a long time now due to cost, but I know that it's the best way to go and will have to get one soon. The only factor deciding how soon I can get one is where I will be getting my paychecks from and how soon I will get my next one.

Well that's not good news, sounds like a life changing event and some age in there. Your a brite guy and I'm sure you'll find something to do with your talents. I know around here you'd be a shoe in as a service writer.

I've left the auto business at least three times in my life. It's never stuck. A GM employee told me years ago once cars get into your blood you're all done. Off and on I keep thinking about quitting the repair business and working as an instructor. I've even approached the local community college here which has an ASEP program. Some of the kids graduating these tech schools have a great start on the technical aspects but very little instruction about the basic approach which makes a technician good. Plus you get summers off!

One of the instructors that would come around and teach GM classes for dealer techs when I was in MT told me he'd been in a car accident when he was young. He'd suffered migraines which would incapacitate him for weeks. He couldn't hold a job that way so he started building hotrods and selling them. He survived for a lot of years doing that. I lived for a couple of years when I was in school doing custom tuning and EFI swaps. I didn't even have a shop. I'd rent space in someone else's place, or use the vehicle owner's garage. Money was tight at times but I survived. If I'd stuck with it I might even have made good money but I chose to go into fleet repair.

Anyway, back to topic. I do a bunch of tuning without the WB. WB is nice to get base maps inline but for many cars it's not necessary imo. I built the Toyota turbo engine and I've never even attached the WB to that one. Emulator, OTOH, is an almost mandatory tool. Imagine flat rate without air tools and you'll understand tuning without an emulator. I've got two here because it's just a damn good tool to have. Install the emulator, leave the cable for that and the datalogging software on the passenger seat, fire up the laptop when you're getting dressed in the morning, and when you get into the car you just have to connect cables and go. At the end of the day review your logs, make changes, upload them to the emulator, and start again tomorrow.

Good luck with everything.

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Originally Posted by EagleMark

Well that's not good news, sounds like a life changing event and some age in there. Your a brite guy and I'm sure you'll find something to do with your talents. I know around here you'd be a shoe in as a service writer.

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Unfortunately I'm only 33 so age is actually a problem in the opposite sense as most people don't see/understand why somebody my age would have such issues. I actually have been a service advisor for about a year and that just didn't work at all. There are too many reasons to list that only having basic car knowledge is better than being an ex-technician although that would seem to be the opposite of what you would think.

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Originally Posted by 1project2many

I've left the auto business at least three times in my life. It's never stuck. A GM employee told me years ago once cars get into your blood you're all done. Off and on I keep thinking about quitting the repair business and working as an instructor. I've even approached the local community college here which has an ASEP program. Some of the kids graduating these tech schools have a great start on the technical aspects but very little instruction about the basic approach which makes a technician good. Plus you get summers off!

One of the instructors that would come around and teach GM classes for dealer techs when I was in MT told me he'd been in a car accident when he was young. He'd suffered migraines which would incapacitate him for weeks. He couldn't hold a job that way so he started building hotrods and selling them. He survived for a lot of years doing that. I lived for a couple of years when I was in school doing custom tuning and EFI swaps. I didn't even have a shop. I'd rent space in someone else's place, or use the vehicle owner's garage. Money was tight at times but I survived. If I'd stuck with it I might even have made good money but I chose to go into fleet repair.

Anyway, back to topic. I do a bunch of tuning without the WB. WB is nice to get base maps inline but for many cars it's not necessary imo. I built the Toyota turbo engine and I've never even attached the WB to that one. Emulator, OTOH, is an almost mandatory tool. Imagine flat rate without air tools and you'll understand tuning without an emulator. I've got two here because it's just a damn good tool to have. Install the emulator, leave the cable for that and the datalogging software on the passenger seat, fire up the laptop when you're getting dressed in the morning, and when you get into the car you just have to connect cables and go. At the end of the day review your logs, make changes, upload them to the emulator, and start again tomorrow.

Good luck with everything.

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I've switched to non-technician jobs and also out of the car business at least 2-3 times also. For 2 years I successfully held a General Manager position at a Zaxby's franchise and only left when my particular franchise went under. I have also had minor success with starting a mobile auto repair business for myself, but lacked enough connections to maintain enough business to continue. Since my issues are physical (neck and other general connective tissue and subsequent nerve impingement problems), any typical tech job that pays flat-rate is not an option as I can still perform the same tasks but at a much slower pace so as to avoid injury and missed work.

I know that wideband isn't a must, but can be of significant aid and save time and have kept pushing it further down my list. I still could benefit from owning one as I could probably secure some work tuning other people's setups. I datalog and make changes the same way that you utilize an emulator with the only difference being that I can't make changes on the fly if I encounter an issue and must allow the extra time it takes to physically remove and program the chip. An emulator is moving up the list of required equipment quickly and I will probably purchase one in the near future. After I secure a source of income I can make more permanent plans regarding the location of my tools and prioritize necessary tool/hardware purchases. I will always perform my own repair and maintenance as long as I can at a minimum. Gotta run for a lunch meeting. I'm going to make a quick starter tune from a fresh unmodified BJYL bin and see how things go with the BLM's locked and other non-critical functions disabled. I'll post the results once I get back on the computer later today.

Thanks,
Phil

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Originally Posted by pmkls1

Unfortunately I'm only 33 so age is actually a problem in the opposite sense as most people don't see/understand why somebody my age would have such issues. I actually have been a service adviser for about a year and that just didn't work at all. There are too many reasons to list that only having basic car knowledge is better than being an ex-technician although that would seem to be the opposite of what you would think.

Thanks,
Phil

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There's a place for you. I can see where a tech would not make a good service writer because he knows to much. If you relate better to cars then people a service manager would be better, or shop where you can still do it all at pace. Or your own low cost shop, no high volume, just low cost for high profit at slow pace.

In my younger days of loving cars more then life itself I was lucky to have a high school auto shop teacher who put me to work at 15 -19, made me go to tech school, made me work nights when the kids were out partying, made me be on call for police towing 24/7 he had told me several times to find something else to do before I was deaf, bad eyesight, poisoned by chemicals, bad knees and wore out at a young age etc... I think he tried to wear me out too... if it wasn't for standing under cars on lift in winter with the heat up high so the fuel lines would thaw, while I was being soaked in a just above freezing waterfall from car, then get it running only to find it needed at least a set of points which we had to install outside while next car was on lift up to ceiling thawing out.. I might not have! so I got out early and kept my love of cars.

It's easy to change direction when young and economy would let a smart willing guy do anything, but I ended up with a pocket full of money and bought a mobile home to fix up and sell, this was so lucrative as a part time job at home I quit a very good position with the State, six months later the wife quit her state job. We bought and sold over 300 homes in 5 years, I was set to retire at 40, had several properties, multiple cars and 3 Harley's, 2 with side cars. Had my son and he was not a year old when at 34 was rear ended in car accident. Month in hospital, six months in bed, walker, wheelchair we closed the business. Have had three back surgeries since and still live in constant pain and have to limit physical abilities so I can relate to spinal issues at young life changing age and understand the need to pace yourself for tomorrow!

Do not take narcotics for pain unless you are in hospital or laying in bed wanting to be in hospital!!! Do not take narcotics to work!!! Do not trust doctors who give you narcotics!!! This is another bad subject you are in a position to fall in.

My advice to you is... "Pace yourself for tomorrow!" When you over do it there is no tomorrow and possibly no next week, or month... this advice was also given to me by my father in law who in his late 30s was hit by a log cabin wall during tear down and same life changing back injuries. He had "Pace yourself for tomorrow!" down pat and always had tomorrow. He also said it will take you about 5 years to become a wimp? It took me about 5 years to understand and It did take almost 5 years before I stopped trying to do to much when feeling good, then had no tomorrow... at 52 I am still having tomorrow...

But hang in there! You will carve out a niche and be fine! :happy:

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Imagine flat rate without air tools and you'll understand tuning without an emulator.

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Great analogy! Like tuning without emulator is tuning by braille.

We have to explore the locked BLM and closed loop. This has only worked for me with Wide Band O2 sensor. Seems I never got it right to get BLM learn disabled to still get BLM numbers in history to adjust VE off of? Killing power and doing short logs has been fool proof. Finding a way to do this without pulling fuse or battery cable would be like adding an air tool.

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We have to explore the locked BLM and closed loop. This has only worked for me with Wide Band O2 sensor. Seems I never got it right to get BLM learn disabled to still get BLM numbers in history to adjust VE off of?

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This is a live or for me, semi live process, to be done with emulator while watching O2 (NB or WB work the same). Add some load, watch O2 reading, adjust VE and / or spark. Reduce load, watch O2, adjust VE and / or spark. This really, really improves driveability because once BLM is re-enabled the corrections from O2 are small. With NB set 60 kPa and up to read about .50-.54V and aim for 20-25 kPa cells around .4V. This sets up the VE table to anticipate changes rather than react to them.

An example: You may typically drive by increasing load temporarily then decreasing when up to speed. MAP goes 65-75 for a bit then flashes below 20 and ends up at 30-45. Typical tuning often puts VE at stoich or slightly lean when you increase load with INT adding fuel to catch up. Then you decrease load, kpa drops. VE table is set up to generate stoich but INT is adding fuel. Now INT has to swing from adding to subtracting, which takes time. Then load stabilizes around 30-45 about the time INT has just finished reducing fuel for mild decel. Now you're a touch lean while INT again plays catchup. Setting up VE to anticipate throttle changes means that INT is reducing fuel slightly under mild acceleration by going lean. When change from high load to low load comes, INT is likely have to add fuel by returning to 128. Right about the time it's settled on a number, load increases but INT is already at 128 so no correction needed.

That just explained why I have better response to overall driveablity and logs when setting VE slightly rich for acceleration and cruise! :happy:

if you go at least slightly lean in the overrun sections of the table, you'll make some awesome exhaust noises as well.

I know how to make deceleration crackle and spit flames? :laugh:

Well, lots of things to reply to here and not sure where to start so I'll probably end up jumping around a lot. I disabled closed loop and locked BLM and INT at 128 just to be sure that absolutely no fueling adjustments would be made. I also disabled DE and DFCO as well. I had to make it to a meeting and was on a very tight schedule so I just made the changes to my latest bin rather than starting over as there are a lot of changes to make that I could easily miss. The overall driveability under pretty much all conditions was significantly improved over any bin since I have installed the engine. Throttle response to quick throttle changes and WOT acceleration felt a little soggy but still strong. I would attribute the soggy feel to being fairly rich. I've noticed that in high temps such as in the mid-'90's and high humidity like today that engines are more sensitive to overly rich conditions. And as such, you can kill a lot of power quickly by adding too much fuel in the summer heat. That is a discovery I made when re-jetting and adjusting the needle height on motorcycle carbs during the tuning process after making other performance modifications. Everything is more pronounced on small engines so you can quickly learn about the effects of any kind of changes/modifications you make. If you get a little rich after adjusting for something like installing a performance exhaust you will discover very quickly that overly rich conditions can make an engine run worse than being on the lean side. One step too high on needle height or one size too big on jetting and you can go from a slightly lean engine that isn't recognizing it's full potential to a slightly rich engine that sputters badly at WOT completely killing the power.

Something that I did note today that is a more recent development would be that it goes very lean at idle whereas the remaining majority of the VE tables would be on the rich side. I believe that the reason behind this is because of the slowly developing MAP sensor issue that I recently discovered and quickly resolved. I vaguely recall making an adjustment of the near idle VE values to compensate for a rich idle condition at some point and it is very likely that the rich idle could have been due to the bad MAP sensor. I have mentioned that I fixed the MAP problem and installed a newer style compact MAP sensor pretty much directly on the vacuum port using a short section vacuum line as a sleeve. And with the true MAP readings at idle the VE needs to be readjusted back to the correct value. Something that I feel is slightly unique about how I have to adjust fueling is the fuel pressure. I have to play a little more with the flow rate values and the VE values in order to balance between making large VE adjustments around idle conditions and avoid exceeding 100% in the high load sections of the VE tables. I'm used to tuning this way also because I began tuning for the purpose of switching over to E85. Many applications don't really need bigger injectors as one would think and I have never upgraded injectors. So the easiest way to add the extra 30% of fuel that is required to run E85 is to simply take the actual flow rate value and skew it to trick the ecm into thinking that the injectors are approximately 30% smaller. By doing so you can usually change just that one value and only need to make little changes to VE tables for fueling.

Back on topic, though, I've always tried to tune for that addictive pop and cackle on decel and have never been able to acheive anything near the desired results. Even with the more aggressive flowmaster model available for my car, I still have a very smooth and quiet decel tone. The only reason I tolerate the droning at any cruising speeds is the ease of achieving that nice raspy note on hard acceleration and the desire for a little cackling on decel that you typically get from a flowmaster muffler. I know that fuel and timing both affect the exhaust sound on decel and know that it is a lean condition that causes popping, but still can't get it to happen. I'm not sure, but thought that retarding the timing a little would add to the popping on decel. I do know that you can alter the exhaust tone and popping by making timing changes though.

Quote:

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Originally Posted by 1project2many

An example: You may typically drive by increasing load temporarily then decreasing when up to speed. MAP goes 65-75 for a bit then flashes below 20 and ends up at 30-45. Typical tuning often puts VE at stoich or slightly lean when you increase load with INT adding fuel to catch up. Then you decrease load, kpa drops. VE table is set up to generate stoich but INT is adding fuel. Now INT has to swing from adding to subtracting, which takes time. Then load stabilizes around 30-45 about the time INT has just finished reducing fuel for mild decel. Now you're a touch lean while INT again plays catchup. Setting up VE to anticipate throttle changes means that INT is reducing fuel slightly under mild acceleration by going lean. When change from high load to low load comes, INT is likely have to add fuel by returning to 128. Right about the time it's settled on a number, load increases but INT is already at 128 so no correction needed.

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The whole scenario described there is almost an exact match for the problems I have been fighting since installing this engine. It has seemed that no matter what I did the results were the same with the ecm always playing catch up and thus fueling was the exact opposite of what is desired as a result. I did find moderate success by modifying the o2 lean/rich values in order to get the ecm to add fuel before the engine was actually leaning out too much. After I review my log from today I will be more certain, but I really don't think that I have much to change before re-enabling closed loop and seeing what happens.

As far as employment goes, I am waiting to see how my appointment with the spinal specialist goes on monday before I even make an attempt at figuring out what kind of job to look for. I have two major issues to deal with and one of those issues is already past the diagnosis and therapy stage and definitely requires surgery that I have been putting off. The other issue with my neck is a more recent development, but I have already exhausted all treatment options that a general practitioner can perform without any improvement. I have a feeling that one of these two major issues are going to require surgery in the very near future and at least one of those surgeries will put me completely out of commission for a minimum of two months. With that very real possibility in mind I can't even begin to ponder what line of work that I am going to be able to go into until I have seen the doctor and obtained an opinion.

Just an update, I have been busy with some home repairs and a room remodel so I haven't driven the car much lately. I have been driving the car with the PCM locked in open loop still . The only thing I have changed since disabling closed loop would be the near idle VE tables to fix the lean issue. Last week the car mostly sat because another problem popped up out of nowhere that just adds to the now comical series of problems that I have had with the car this year. I had Degreased the engine compartment after replacing the leaking A/C compressor to wash off all of the UV dye that was all over. I went to start the car, but all it did was crank over shortly and then backfire. When I tried to crank it again I could hear the starter motor running, but it was spinning freely. I took a look under the car and found the starter motor dangling by the wire that attaches to the solenoid. The housing had completely shattered when the engine backfired. So, needless to say I had to get another starter and also put it on in the gravel driveway (no fun at all). Anyhow, the car has been running so good and anytime I have needed it I was on a very tight schedule so I haven't had time to try tweaking the VE and reenabling closed loop. Now that I have a little better idea of what my woes were caused by and what direction to go in I am wanting to get back to trying to sort this thing out. Next week is no good because I have some trans repairs to make on the wife's car so I am hoping that the week after I will have some time to get back to my car.

Alright, I'm reviving this old thread for an update so as to avoid having to reitterate the long process that has led up to this point. But I have had another breakthrough that confirmed that I was battling another issue and is now resolved. So, I finally got around to installing a Holley TBI unit that I scored for nearly nothing ($40) a while back that was meant for a 4.3 S/T truck. There are only a couple minor and unimportant differences between this unit and one intended for a 5.7 or an F body. The throttle bores are still 2" 454 size bores that Holley rates at 670cfm. This unit is new enough to use the smaller Delphi bottom feed injectors that are capable of operating properly in low and high pressure systems ranging from a 12psi TBI system to a max of ~70psi. The main difference in this unit and one meant for a 5.7 V8 are the injectors are smaller for the smaller engine which are actually better suited for my odd setup. I got the TBI unit installed and everything adjusted and then set the fuel pressure to 21psi. That is the lowest pressure that I can run at idle without the regulator staying open and the pressure dropping drastically when you snap the throttle. Ahyhow, these injectors are rated at 72pph @ 21psi which is a bit big for my engine, but still less than the original injectors at these pressures. So, I updated the injector flow rate and the latency settings in the bin and burned a new memcal and took it for a test run. My first impression was that the car is a beast compared to how it drove with the original throttle body. I liked having the bigger throttle bores as I know that even the stock vortec bottom end could handle way more flow than the dinky 5.0/5.7 throttle bodies can provide. But with the stock pathetic exhaust manifolds from the original 305 still on the car I didn't expect the larger throttle body to make much, if any, of a difference. This was especially because it still made that "4 barrel sound" under heavy throttle that typically indicates that the engine can't use that much flow because either the cam is too small or the exhaust is too restricted. Back on track though, not only could the engine use the extra air, but it likes it a lot. Don't get me wrong, I have driven several 500hp+ cars including late model Corvette Z06's and even a 638hp ZR1 once. So, I'm under no impression that I have a monster by any means, but the difference was dramatic especially given that the car already ran pretty well after getting the fueling a little better under control.

Now, as for the relevant information regarding the breakthrough I've had. I had been told and then became very suspicious that TBI injectors behave very erratic and unpredictable when used at high fuel pressures such as the 30psi I was running. After having gotten the tuning under control and being able to make small adjustments and then check the results I began to notice that the fueling was still a little too inconsistent. Now that I have changed the throttle body and am using different injectors I can see just how erratic the old injectors had become. I know that the better flowing throttle body should have a little bit of an effect on the VE tables, but the ones I have been tweaking for months are now WAY off with the new unit. I am quite positive that it is because the old injectors were not performing in a consistent manner at all. After going back and looking at some O.E. VE tables and some of my older ones there is a natural curve to them all. In my latest VE tables, they are MUCH flatter. I believe that this is because with the original injectors once the fuel pressure is increased past a certain point the fuel delivery isn't as linear as you would expect. I know that I have seen data before showing just that and that is what I am basing my hypothesis on after seeing the big difference with the new injectors. The important fact in all this is that I now seem to have consistent hardware to work with that will allow me to finally work out the majority of the bugs that have plagued me since swapping engines. The last bit of work that I have left now is to replace my lifters that I believe to be causing a few funny quirks. I've had a set sitting in the basement that I began to recondition months ago that got moved to the bottom of the list as other work rolled in. But, I believe that I should be able to get back to them soon and hopefully get them installed sometime this winter.