$EE / LT1 Injector Swap Running Rich

[spfautsch]

Moderately built LT1 / bored .030" over w/ ported heads and intake, moderate cam (CC 467) and 1 5/8 tube headers. Been tuning with the factory 24 lb injectors since finishing the rebuild, and have good confidence my VE tables are rock solid - at least in "normal" driving ranges (all load ranges up to about 3200 rpm). Runs great in SD mode, makes incredible power up to fuel cutoff @ 6800 rpm but hard to tune there because the rear tires aren't big enough or roads long enough.

So having a long weekend to tinker with it, I thought I'd try installing the no name brand, auction site injectors I bought when I started the build. The specs provided claim these are 36lb/hr / 380cc/m "skinny" bosch gen 3 clones. The auction shows Bosch 0280155737 as an equivalent part #. I'm starting to think I might have wasted $90 (I know, why go cheap here). After four months of tuning this isn't the only thing I've found I shouldn't have pinched pennies on, but a poor man has to try...

Initial start I used 36.0 lb/hr for the injector constant, and an extrapolated offset / voltage table that the seller provided. It did start and run, but with newly installed (dry) injectors and the fuel rails not completely purged of air it wouldn't last long. Subsequent start attempts seemed to flood instantly. Zeroing the injector offset adder table and cutting all the tables with "* prime pulse width vs coolant temp" (adder) tables by half made no difference. Still would only start after opening throttle to clear the flood.

Next steps were to increase the injector constant by 1lb / hr, followed by cutting the injector offset vs voltage table by 25%. Twelve or thirteen flash cycles of the E side later I'm at offsets lower than the stock Rochester specs and 42lb / hr IFC.

Oddly, when warming up at idle with commanded AFR of 14.0:1 the narrowbands are indicating a lean condition of ~130mv. Then closed loop / BLMs turn on and it immediately turns pig rich (~850mv average on the narrowbands over a short drive).

This is my first injector swap, so I'm sort of grasping at the idea I must have forgotten something obvious.

Any thoughts or ideas appreciated, including recommendations for a quality set of 32-36 pound 3 bar injectors with a known good datasheet that I won't have to sell a kidney to own. I would especially like to make these triple-C injectors function acceptably for the time being, but at this point the money lost on the junk injectors is somewhat irrelevant. I've built the valvetrain and reciprocating assembly to survive 7000 rpm. That, in addition to the cam, port work and exhaust it should be able to touch on 460-500 crank hp which is (according to what I've read) well beyond the flow capability of the 24lb factory injectors north of 6000 rpm.

[dzidaV8]

Go and get known GENUINE Bosch injectors. Green giants should be OK here. I've had chinese knockoffs get stuck open suddenly and flood the engine completely. Then you try to start, and destroy the hydrolocked engine...
Not to mention complete weirdness trying to tune that shitty injectors...
It's really not worth it to waste your time and good engine with cheap injectors.

[spfautsch]

Greens are 42lb / hr - any problem with those at hot idle on a 355ci / 5.7L LT1?

[dzidaV8]

Bosch D3 series injectors are well controllable at low pw, so I don't think you'd run into problems. I used them on 383 sbc that made 420hp on a dyno.
In your case red Bosch D3's (0 280 155 759) 32lb/hr should suffice to around 430bhp...
Those are two injectors with known good tuning data, so I'd stay with them.

[Terminal_Crazy]

Greens are 42lb / hr - any problem with those at hot idle on a 355ci / 5.7L LT1?

Hi , saw the email.

Don't know about the greens..
I've had
30lb Venom from TLF performance.
30lb Modified Bosch 3(stainless later core) from Fuel Injector Connection
42lb Modified Bosch Blue Demon 3 from Fuel Injector Connection.
(tried several sets to rule the injectors out when I had the manifold issueand for peace of mind.).

I did get some figures for the offsets with them but couldn't make much sense of them.

Solomon did me an initial tune which was drivable OK but OL and I was used to BLM tuning so went closed loop.

Since going OL with the wideband, my VE tables look nothing like they did CL and this motor likes to drink fuel.
Solomon zeroed out the injector offsets.
I've played with them without any better success.

Are you using a wideband yet?
I've always tried to get the idle right first. Currently I think my wideband needs a hard drive to get hot.
Starting up tonight Idle was at 9:1 . After the run I'm at 11+

Also I've had to lower my injector constant several times as I keep hitting 100+VE Table values.
Steveo has said drop it by say 10% and the VE tables by the same amount. This doesn't seem to be accurate here. I don't know why. It takes 3-4 logs to get back to the ball park.

A couple of points off around idle also seems to make a huge difference.


I'd say drive the car for half an hour then start playing with the tune.

If the car is running i'd just pull some fuel around idle.

Are you
Open or Closed Loop?
Narrow or wideband ?
Speed Density or MAF ?


Mitch
Who doesn't seem any further on than 6 months ago!

[spfautsch]

In your case red Bosch D3's (0 280 155 759) 32lb/hr should suffice to around 430bhp...
Those are two injectors with known good tuning data, so I'd stay with them.

I'm trying to decide between the greens (0280155968), some remanned + modified blue demon 3s mentioned by mitch (very affordable), and 34 / 36lb 0280155868s. The latter were used on the 98-05 supercharged 3800 buick engines so I would think I could glean an offset table from a factory bin from one of those. They're also available new on a certain auto parts site for a very reasonable price.

I'm at a point where I have some health issues eating into my wallet, and will have to sell another toy or two to afford this purchase (especially the greens). But I'd rather have more and not need it then have my car strapped to a dyno and find I can't feed the beast above 6000 rpm.


Solomon zeroed out the injector offsets.

Do you mean the 'Injector Offset Adder' table (tunerpro)?


Currently I think my wideband needs a hard drive to get hot.
Starting up tonight Idle was at 9:1 . After the run I'm at 11+

Narrowbands are no different. Bringing the car up to temp at idle my BLM splits are horrendous. Idling after driving they're generally within 4-6 counts.


Also I've had to lower my injector constant several times as I keep hitting 100+VE Table values.
Steveo has said drop it by say 10% and the VE tables by the same amount. This doesn't seem to be accurate here. I don't know why. It takes 3-4 logs to get back to the ball park.

I would suspect the proportional relationship between injector flow constant and the fuel calculation that uses the VE table aren't 1:1.


I'd say drive the car for half an hour then start playing with the tune.

If the car is running i'd just pull some fuel around idle.

Done all that. The chinese injectors are going to get turned into keychain fobs. If they're rated at 36lb/hr and the injector constant in the tune is 46 lb/hr and I've tried a rainbow of different offset tables, something's rotten when the car won't start because it's flooding on first crank every time.


Are you
Open or Closed Loop?
Narrow or wideband ?
Speed Density or MAF ?

Currently SD CL with narrowbands only. I found out what I was doing "wrong" with trimalyzer and my last tune of VE seemed to be solid after logging a few hundred miles to verify. I did enable my MAF to attempt to calibrate it, but I suspect I have a wire or connector causing problems because it stopped working inside of 10 minutes.

[Terminal_Crazy]

Do you mean the 'Injector Offset Adder' table (tunerpro)?



Yes.

The voltage offsets I have are slightly higher than the stock figures at around 13V but I don't think they affect much if the motor is running well (and electrics are stable). (same sort of curve).


If your injector constant is upto 46 on 36lb injectors they should be running _very_ lean.
I'm now down to 38.5 on the Injector Flow Rate on the 42lb to keep the VE table within range.

Running CL here even with a crappy VE table, the car would tune itself back happily enough.

I hope the new injectors will cure your issue.

Mitch

[spfautsch]

If your injector constant is upto 46 on 36lb injectors they should be running _very_ lean.

You would think. The MostPlus injectors came out and stockers back in. Model # MO2A36 - if anyone is considering them save yourself the headaches and buy something reputable.


I'm now down to 38.5 on the Injector Flow Rate on the 42lb to keep the VE table within range.

I need to do this myself as I'm out of headroom in the bottom left corner of VE. I might try scaling with the factory injectors to see what happens. I'd hope a complete remap of VE would not be necessary. This is the primary reason I chose to wait to install the bigger injectors - I know the constants for the factory Rochester / Multecs are right, and if nothing else has changed but the injectors logic dictates you should be able to get back to where you were by simply tweaking the IFC and offset vs voltage table.

[spfautsch]

Remanned 42lb injectors showed up yesterday. Lacking any flow bench data (what happened there FIC?) I punched in 43.0 for IFC and used an offsets table I found for the injector part #s (12561462 - LS1/LS3 injectors). Initial start was ok, but it was quite a bit rich so instead of increasing IFC I took 5% off my VE table except for the 10 cells that were maxed out at 99.6. Now it's flooding when started cold (I have to pedal it to clear the flood), and sputters some when restarting hot. A short drive shows my trims are pretty close with these changes (I've been targeting 3% rich).

Anyone have any ideas on how to prevent the cold start flooding? I haven't messed with any of the tables named "* prime pulse width vs coolant temp" since they didn't seem to have any impact on initial start pulsewidth previously.

[Terminal_Crazy]

As I've said I'm not using any offsets.
If they aren't right, the fuel curve will be off anyway and you'll be retuning anyway to correct it.

I've only bothered to lean out the Open Loop AFR table to lean out during startup & the Initial AFR Enrichments vs Coolant.
I don't expect the other tables will make any huge difference to the startup.

At idle you will be running around 2ms any small adjustment will be a relatively large jump percentage wise.
Log and adjust VE tables or just lower the corner of the VE table from just above idle (rpm & map) ( or drop the whole table 3% first ).

Mitch

[spfautsch]

I think you're confusing the offset vs voltage table with low pulsewidth adder. The tune you shared with me had a populated offset table. I've zeroed the low pulsewidth adder table which is what I think you're talking about.

It's idling fairly well, not exactly like it was last month when my "long way to work" road was horribly mutilated by the Missouri Department of Transportation (we rednecks refer to it as chip-n-dip (https://en.wikipedia.org/wiki/Chipseal)). But it's also 100F ambient and 50% relative humidity here so I haven't run it in this type of weather much to have a "baseline". Driveability is good. The seat of pants dyno says mid-range power isn't great, but again the weather may be a variable. I won't be able to collect much data to verify for quite some time, but my worst trim cell after a 10 minute drive was 5% rich so I'm not thinking a big VE remap will be in order.

I'll experiment some and report back. I'm beginning to think there are some IPW calculations happening during cranking that don't reference the VE table or the injector flow constant.

[spfautsch]

Well color me stupid.:mad1: No sooner than I clicked "post" it occurred to me there's a "Crank Volumetric Efficiency Vs. %TPS Vs. RPM" table that I hadn't adjusted to match the main VE tables.

I'll have to test more after she cools down but it sprang to life almost as quickly as it used to (feels like within the first 180 degrees of rotation). :happy:

[Terminal_Crazy]

I think you're confusing the offset vs voltage table with low pulsewidth adder. The tune you shared with me had a populated offset table. I've zeroed the low pulsewidth adder table which is what I think you're talking about.

It's idling fairly well, not exactly like it was last month when my "long way to work" road was horribly mutilated by the Missouri Department of Transportation (we rednecks refer to it as chip-n-dip (https://en.wikipedia.org/wiki/Chipseal)). But it's also 100F ambient and 50% relative humidity here so I haven't run it in this type of weather much to have a "baseline". Driveability is good. The seat of pants dyno says mid-range power isn't great, but again the weather may be a variable. I won't be able to collect much data to verify for quite some time, but my worst trim cell after a 10 minute drive was 5% rich so I'm not thinking a big VE remap will be in order.

I'll experiment some and report back. I'm beginning to think there are some IPW calculations happening during cranking that don't reference the VE table or the injector flow constant.

I did say to get your data first!

Nope, no confusion there. I've got the Voltage offsets set, I have since zero'd out the low pulsewidth adder.
As I don't know that they are correct, close or way out, I've removed them from any interference in the data logging.

This motor will start at 7.5:1 or less and 22.4:1 or more without any issue.

If you do adjust your VE table i'd only adjust it fractionally from what you are calculating so it doesn't shift too far from where you are now.

Mitch

[spfautsch]

This motor will start at 7.5:1 or less and 22.4:1 or more without any issue.

You also have another 30 cubic inches of displacement, which is not insignificant.


If you do adjust your VE table i'd only adjust it fractionally from what you are calculating so it doesn't shift too far from where you are now.

I had the opportunity to do some more logging this afternoon and found the trims aren't very far from what they were with the factory injectors. I feel confident I'll be able to tweak the offsets and injector constant to "a happy place" without significant remapping of VE.

The Crank Volumetric Efficiency Vs. TPS Vs. RPM table looks to have the biggest influence on my starting flood problems. Extremely rich pulsewidths on a 24 lb injector are a completely different animal with a ~43.5 lb injector setup. In addition, this cam is right on the edge of ridiculous in my book - the idle cells are around -30% from the factory tune. So far I've tried three different scalings on this table, all with extremely noticeable and some very promising results.

I'll be happy to spend whatever time it takes to get this one just right because it's hard to describe how satisfying the sound is when the engine breathes to life within 500 milliseconds of crank start.

[spfautsch]

Is anyone aware of a "minimum injector pulsewidth" constant in $EE?

I ask because I've removed enough of my Crank VE vs TPS vs RPM table that warm starts are coming in at 0.75ms pulsewidth and don't seem to go lower. I'm just curious because the specs on these injectors show a minimum PW of 0.52ms.

I'm pretty sure I've run the crank VE table too lean, but it's hard to tell. It seems to be starting rough (long crank, sputtering start) when cool, warm and hot now. There seems to be a "black hole" startup spot where the ECT reads around 140f where once the valves have cooled down the difference between flooding and firing is awfully narrow.

[dzidaV8]

There you go, I updated Steve's EEX.xdf with some parameters, including minimal injector PW.
Stock minimal PW is 1.4ms.

11971

[spfautsch]

There you go, I updated Steve's EEX.xdf with some parameters, including minimal injector PW.
Stock minimal PW is 1.4ms.

Well thanks, but this just raises about a dozen more questions.

1) if the minimum is 1.4ms why am I seeing 0.75?

2) I must have been using an extremely outdated version of steveos xdf, or have you added / changed a lot more?


1st Prime Pulse Width Vs. Coolant Temp. table controls the injector pulse width of the first prime fuel pulse during cranking as a function of engine coolant temperature.
Similarly the 2nd Prime Pulse Width Vs. Coolant Temp. table controls the injector pulse width of the second prime fuel pulse during cranking as a function of engine coolant temperature. These tables were in the '96/97 LT1 calibrations. In the '94/95 LT1 calibrations these two tables are combined into a single table (Prime Pulse Width Vs. Coolant Temp.).

If the engine is still cranking after the time specified by the 'Added Prime Pulse Enable Crank Time Vs. Cool. Temp.' table then another (Added) prime pulse is output and the pulse width of this added pulse is specified by the 'Added' column.

<mind blown>

The version I was using had these three tables separate, and none had any info about what the parameters effect.

Questions 3-12) can anyone explain the $EE startup routine in detail? The description of the prime pulse width table makes it sound like there are no AFR calculations happening during this "prime" sequence. What are the conditions for the prime sequence to be entered? What is the function of the "Ext. Crank AFR vs. Low Res Pulse vs. Coolant Temp" table? This one also makes it sound like AFR calculations are not referencing VE or the injector flow constant.


When cranking, the AFR must be determined using the low resolution pulse only, as not enough stable data is available from the MAF or SD systems. This table configures the ratio of fuel to low res pulse.

This has me wondering if there's an annotated disassembly floating around somewhere. I'm too old to try deciphering motorola byte code again - my brain will turn to dust.

[dzidaV8]

Yes, I modded the XDF here and there to suit me better.

Commented disassembly is here (http://www.gearhead-efi.com/Fuel-Injection/showthread.php?335-16188051-and-16181333-PCM-Information-EE-EEB).

Basically, at startup there will be two prime pulses delivered (1st and 2nd, as per tables) at each low res pulse (IIRC). After the first 2 prime pulses, fuel is delivered using Crank VE table and Cranking AFR table. If the engine doesn't go above running RPM in certain time (Added Prime Pulse Crank Time table), there will be another (added) prime pulse, as per 3rd table.

As for PW lower than minimal, I think that prime pulse might not be limited by that? Need to check the disassembly.

[spfautsch]

Commented disassembly is here (http://www.gearhead-efi.com/Fuel-Injection/showthread.php?335-16188051-and-16181333-PCM-Information-EE-EEB).

Thanks! Apologies for not having found it on my own.


Basically, at startup there will be two prime pulses delivered (1st and 2nd, as per tables) at each low res pulse (IIRC).

Having not scaled the prime pulse tables for the bigger injectors explains why I'm flooded before the cranking VE table takes effect.

Thanks for the simple and direct answers. Had I known there was a commented disassembly right under my nose I'd have at least made an effort. Though looking at them I would have spent days or weeks trying to find those answers. Good stuff nevertheless! :thumbsup:

[dzidaV8]

Having not scaled the prime pulse tables for the bigger injectors explains why I'm flooded before the cranking VE table takes effect.

That's why I combined those three prime pulse tables into one - to make scaling them for different injectors just one multiply or divide operation.

[spfautsch]

I can't thank you enough. Had I known about the prime pulse width table(s) not referencing injector constant it would have saved me dozens of E-side flash cycles and a lot of frustration. I got close enough on the first attempt by scaling VE and the prime table according to what I thought would work that I'm not sure fine tuning will be needed. I'll report back once it cools to 60c.

Since it sounds like you've done a few of these, are there any other pitfalls you can think of warning me about?

I also applied all the SD / VE logging I've done since the injector swap, which produced some changes in the neighborhood of 5-6%. I was looking for a distinct pattern of shifting from lean to rich with RPM that would indicate having the wrong offsets, but saw nothing of the sort.

From here I'm off to building a vss + gps driven arduino based performance computer so I won't have to rely on butt dyno "numbers".

[Casey96SS]

I am glad I found this thread. I have had problems with flooding during hot starting which I traced to the larger 30lb Bosch III injectors from FIC I am running. I have two questions.

1. How do I determine the minimal injector pulse? Would this come from FIC?

2. What would be the correct way to scale the prime pulse width table for the larger injectors? Would I just take 24/30=.8 and then multiple the entire table by .8?

[spfautsch]

I meant to post an update on this as more fine-tuning was needed. I still don't think I'm "dead on" but it's definitely improved. The way I've been comparing is to warm the engine up to normal operating temp by driving and then let it cool to 60c/140f which is where gasoline stops vaporizing readily. I'll then log the start with eehack and step through the number of frames between when the knock count first increments (caused by the Bendix drive engaging) and when the ECM has determined the engine is running by entering cell 16. For "cold" starts (anything below about 40c) it's generally about 7-8 frames or roughly 750 ms. I've gotten warm and hot restarts down to around 8-9 frames. Unfortunately it's a time consuming affair because once you start and run the engine for any amount of time it quickly heats the intake valves back up, improving the fuel atomization and warm start characteristics.


1. How do I determine the minimal injector pulse? Would this come from FIC?

I doubt the minimum pulsewidth is a factor for you, especially with 30lb injectors. It doesn't appear to apply during startup anyway, and at idle I'm guessing you're around 1.8ms? Nevertheless FIC should be able to supply you with this, or if they left any identifying numbers on the injectors you can "sleuth" it. Did you get a flow sheet with yours? I didn't, and I'm slight annoyed by that. :-\


2. What would be the correct way to scale the prime pulse width table for the larger injectors? Would I just take 24/30=.8 and then multiple the entire table by .8?

Sounds about right. Another table you may want to experiment with taking some fuel out in the warm start temps is called "Crank AFR vs. Low Res Pulse vs. Coolant Temp". The factory tune has some fairly large values in the first two pulses in this warm / hot start region. I basically halved the entire table (*0.50) for everything starting at 44c and above, but keep in mind I'm running 42 lb injectors so you may want to start at *0.80 and work your way down. Over the last few days I've been taking about 15% off the first two (leftmost) columns from 44c and up, and retesting. It currently looks like this.


01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16
-40 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8
-28 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8
-16 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
-04 1.8 1.8 1.5 1.5 1.5 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7
08 2.3 2.3 1.9 1.9 1.9 2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1
20 5.6 5.6 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2
32 6.6 6.6 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3
44 7.5 7.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5
56 9.2 9.2 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4
68 9.2 9.2 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4
80 10.8 10.8 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4
92 11.7 11.7 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4
104 11.7 11.7 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4
116 11.7 11.7 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4
128 11.7 11.7 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4


I'd really like to have a better understanding of how exactly all these tables factor into the pulsewidth calculations, but I'll settle for results.

[Casey96SS]

Cool, thanks for all the info. I always wondered why I get the knock every time I start the car, makes sense that it would be the starter!

No, I did not get any data sheets with my injectors. They did email me the offsets after I asked twice. I will ask them about the minimum pulse. Unfortunately they ground off the original part numbers and put theirs on there. They have really done a lot for me though. My first set of orange 30lb Bosch III from them were really hard to start when the engine was hot. It would crank for 5 to 10 seconds and then barely fire up. I sent them back for testing, they found no problems and sent them back. I contacted them again after starting was still bad. They went ahead and sent me a whole new set of gray 30-lb Bosch III. This set has been much better. Hot starting is pretty good, but I think I can get it a little faster and crisper if that makes sense.

I will try playing around with those tables today to see if that makes any difference.

[spfautsch]

Hope it helps, and good luck! I wish there was a more scientific method for this other than trial and error. Evidently it's a problem that's a lot more prevalent for those of us who've stuck with the 3.48" stroke crank.

With your cam you might want to take about 30-40% off the Cranking VE vs TPS vs RPM table also. Alone that made very little difference for me but that seems like a pretty choppy cam so it may factor in. I also like zeroing all the cells above 12.5% tps in that table so if you do flood it you can stab the pedal and clear the flood while it's cranking.

Out of curiosity, what valve springs are you running?

[Casey96SS]

Running the same double springs you are. I used to have beehives and then upgraded to the Lunati springs last year when I had Lloyd freshen the heads up. I figured it was worth the piece of mind to have a double spring vs a single.

My first hot start went well after I adjusted the tables. I'll have to get some more runs on it to see how it goes. Glad I know what to adjust now!

[spfautsch]

I'm happy to see someone else building a standard displacement LT-1. I've always preferred building a smallblock that puts the fat part of the power band over 5000 rpm. As long as your rod bolts are decent, your rod bearing clearance isn't over 2 thousands and your valvetrain will handle it, a moderately built 350 with a nodular iron crank will happily produce good power at 7000 rpm all day long. What's your rev limit set at, and have you hit it yet?

I've yet to get my warm start "perfect", but have been distracted by numerous other things wanting tweaks. It is firing immediately and running without having to crank a long time (or a second time) now, but doesn't quite breathe to life as it did with the factory injectors + tune. Even if I can't get it perfect I'm happy not to have to pedal it to clear the flood.

[Aroberson77]

I'm happy to see someone else building a standard displacement LT-1. I've always preferred building a smallblock that puts the fat part of the power band over 5000 rpm. As long as your rod bolts are decent, your rod bearing clearance isn't over 2 thousands and your valvetrain will handle it, a moderately built 350 with a nodular iron crank will happily produce good power at 7000 rpm all day long. What's your rev limit set at, and have you hit it yet?

I've yet to get my warm start "perfect", but have been distracted by numerous other things wanting tweaks. It is firing immediately and running without having to crank a long time (or a second time) now, but doesn't quite breathe to life as it did with the factory injectors + tune. Even if I can't get it perfect I'm happy not to have to pedal it to clear the flood.

I built a standard displacement LT-1 as well. where is your rev limiter at? I set mine around 6300

[Casey96SS]

I'm happy to see someone else building a standard displacement LT-1. I've always preferred building a smallblock that puts the fat part of the power band over 5000 rpm. As long as your rod bolts are decent, your rod bearing clearance isn't over 2 thousands and your valvetrain will handle it, a moderately built 350 with a nodular iron crank will happily produce good power at 7000 rpm all day long. What's your rev limit set at, and have you hit it yet?

I've yet to get my warm start "perfect", but have been distracted by numerous other things wanting tweaks. It is firing immediately and running without having to crank a long time (or a second time) now, but doesn't quite breathe to life as it did with the factory injectors + tune. Even if I can't get it perfect I'm happy not to have to pedal it to clear the flood.

I would have done a 383 but this was my first full engine build so it was a bit of a learning experience. I did not want to put the extra money into it in case I really screwed something up. It does has forged 6" Scat rods with ARP bolts and lighter Wiseco pistons. I kept the quench pretty tight. The plan was to be able to rev it to 7,000.

Currently have the rev limiter set to 6,600. Have only had it to about 6,300 so far. Only have about 500 miles on it. Working on getting the fueling a timing dialed in better before I really wind it up. Will eventually set the limiter in the 6,800 to 7,000 range when I am comfortable with how it is running. It does like to pull up top though. Looking forward to getting my 4.10 rear swapped in.

It seems the changes I made to the cranking tables really helped with hot starting. It starts about like it did stock. It fires after a couple revolutions. It could probably get better but I am much happier with it now.

[spfautsch]

I almost went 383 when I found out that it's no longer cost effective to have rods re-sized, and what speed shops are charging for crank balancing these days. But I decided I didn't want to cobble on connecting rods or the block, and the 4x3.48 bore x stroke combo is pretty well proven.

I've hit my 6800 rev limiter a couple times when the pavement was cold and it would just bake the tires off immediately above 4500 rpm. But now that the roads have warmed up I'm finding the extra revs are nice in the 1/4 because I'm able to finish in 3rd gear.

Ultimately I'd like to tear it back down and go the 6" rod + single eyebrow forged slugs route and possibly have the decks zero cut. But with what I spent on this go-round I may not have the disposable income to do that for several years.

I'm pretty much done fine tuning VE and am waiting for a GPS board to build my performance computer for tuning WOT. I may have time this weekend to do more fine tuning on hot starts. I've gotten to the point it's starting reliably but not very "enthusiastically" between 120F and 150F. Hot starts are a little less "enthusiastic" also. As I mentioned previously it seems to fire on the first full compression stroke, but instead of picking up revs exponentially like the stock tune it sort of comes up to speed over two or maybe even three revolutions. I guess I'll start working in small increments on hot start to see whether it wants more or less fuel.

[spfautsch]

I'm not sure I've gotten the start tables perfect but I did at least determine without a doubt what had me chasing my tail on this one.

The "Prime Pulse Width vs. Coolant Temp" table, along with most of the others in this category are stored as 8 bit cells which are then scaled by the mask by multiplying with a floating point constant to come up with pulsewidth. For this particular table that value is 1.5625. This leaves a fairly limited range of low pulwidth values for tuning to large injectors (minimum of 1.56, and multiples thereof - 3.13, 4.69, etc). What I was doing wrong was blindly scaling the table in TunerPro, saving the table and then saving the bin and flashing. My dumb *$$ finally caught on when I was working on hot starts last night and had added 10% to the rows between 68 and 128 ect, and eehack couldn't find any differences to write. The changed cells were getting pumped back through the conversion formula and resolution was being lost. <planting forehead firmly in palm> I suppose this begs the question - is there a way to view / edit the raw hex data in TunerPro?

So assuming I won't be able to get warm starts (around 60c) perfect, I'm weeding through the disassembly to see if I can change the floating point scalar constant used in the conversion formula. Cutting it in half should give me ample resolution to fine-tune this one table.

[dzidaV8]

You can view raw data in TunerPro, just right click on the table and select "Show raw hex".

[spfautsch]

Duh, can't believe I missed that. Need a bigger screen or bifocals.

I'm trying to find where the lookup value from this table is scaled by 1.5625, but don't speak much motorola. I think this is the call loading the table but it looks like it's multiplying (something) by 018f, which unless I'm using the wrong endianness doesn't equate to 1.5625. Edit: or is L018F identifying a memory location?


3758 B6 01 93 ldaA l_0193_CoolTmp_fltrd_$f0_max_$e0
375B CE 26 82 ldX #$2682
375E BD 78 12 call l_7812_lkup2d_nooff_16spc
3761 F6 01 8F ldaB L018F
3764 3D mul
3765 05 lslD
3766 24 02 bcc @32
3768 86 FF ldaA #$FF
376A CE 26 80 @32 ldX #$2680
376D BD 77 81 call l_7781_A*X->D_8x16_Mult_sub
3770 1A 83 7D F0 cmpD #$7DF0
3774 23 03 bls @33
3776 CC 7D F0 ldD #$7DF0
3779 FD 01 A1 @33 stD L01A1
377C B6 01 90 ldaA l_0190_NTPSLDT_a
377F B1 26 D9 cmpA L26D9
3782 23 05 bls @34
3784 CC 00 00 ldD #$0000
3787 20 18 jr @36

[kur4o]

That is barometric correction.

18f is result from baro table lookup correction.

[spfautsch]

Any chance you could steer a machine code impaired hot rodder in the right direction? It's been around 10 years since I last changed a jmp to a nop, and a lot of brain cells have died since then.

I'm afraid "perfection" may require adjusting the scalar on this one unless there's something else I'm missing because I've tried all three possibilities in the 56c row.

0x02 (3.13ms) too lean
0x03 (4.69ms) starts with a bit of a stumble, think slightly lean
0x04 (6.25ms) floods when the valves have cooled
0x05 (factory calibration for 24lb injectors) floods always

Edit: After scaling the "Crank AFR vs Low Res Pulse vs Coolant Temp" table properly to the nearest hex value, it may be close enough to pass as "perfect". Will report back in the next day or so.

[dzidaV8]

I think the parameter you are looking for is "12680 BASE BPW FOR STARTUP ,used to calc prime pulse width used with 2682" available in EEXtra.xdf

The looked up values from prime pulse tables are mutiplied first by BARO multiplier, then by this base PW to get final priming PW. I think the XDF definition for prime pulse tables should be modified to take that base pw into calculations. I'll try to update the EEX.xdf and get back to you.

[spfautsch]

Thanks! I spotted that in the disassembly and thought it might be what I was looking for, then had to get started grilling dinner so tuning went out the window.

Don't go out of your way unless you really want to - I can probably figure this one out from here. I've been working on this table raw so I can calc the pulsewidth by hand when I change it initially. I'm pretty sure the only row I'll need to tweak will be 58c and I'll do that in hex.

[dzidaV8]

Actually, there is a mistake in the EEXtra.xdf. The 0x2680 is used as an immediate value, not an address. So there are actually 4 places that have this value hardcoded ( E side lines: 0x376A, 0x379B, 0x4E18, 0x54F7). In order to change the base PW you need to adjust all of those constants. I'll send you the updated xdf when I get back to my PC at home.

[spfautsch]

I think it's a pointer - look at the multiplier function at 7781. The disassembly calls this l_7781_A*X->D_8x16_Mult_sub



;;* CALL WITH:
;;* A Reg = 8 BIT Multiplier
;;* X Reg = Address og(f) 16 bit Muliplicand


All those calls appear to be referencing the 1st, 2nd or adder prime pulse width tables, so my intention is to scale the BPW multiplier at 2680 by 60% and restore the factory calibration data to the prime pulse width table(s). If I don't have enough resolution to fine-tune with that I can always scale it further and then increase the tables accordingly. The largest values there are 0x56.

What I'm still trying to wrap my head around is how 1.5625 factors in - is it based on cpu clock frequency maybe?

[dzidaV8]

OK, you're right, it's a pointer.

So the program goes like this:

3789 B6 01 93 @34 ldaA l_0193_CoolTmp_fltrd_$f0_max_$e0 ; Load Coolant Temp to A
378C CE 26 91 ldX #$2691 ; Load pointer to 1st prime pulse table to X
378F BD 78 12 call l_7812_lkup2d_nooff_16spc ; Look up 1st prime pulse value from the table
3792 F6 01 8F ldaB L018F ; Load calculated Baro correction (128 - no correction)
3795 3D mul ; multiply
3796 05 lslD ; shift D left and use A (divide by 128)
3797 24 02 bcc @35 ; branch if no overflow
3799 86 FF ldaA #$FF ; if overflowed, load max prime pulse value (256)
379B CE 26 80 @35 ldX #$2680 ; load pointer to Base Prime PW
379E BD 77 81 call l_7781_A*X->D_8x16_Mult_sub ; Multiply 1st prime pulse and Base Prime PW
37A1 1A 83 7D F0 @36 cmpD #$7DF0 ; compare to 0x7DF0 (32240)
37A5 23 03 bls @37 ; branch if lower
37A7 CC 7D F0 ldD #$7DF0 ; if higher, limit the calculated 1st prime pulse to 0x7DF0 (32240)
37AA FD 01 A5 @37 stD L01A5 ; store the calculated 1st Prime Pulse

The same routine is used for 2nd and additional pulses.

The thing is that the Base Prime PW from 0x2680 is 0x6666 in most bins, and is limited in code to 0x7DF0. So when pulse multiplier from the table is >1, it will be already limited?? Something is off here.
I haven't been able to find how to convert the raw values to milliseconds yet.

It's also strange that the Baro correction is applied BEFORE multiplying the base PW, it makes little sense to scale as small values as those ( 2, 3, 4 etc...).

[spfautsch]

Search me...

I generally don't like putzing around with things I don't (believe) I fully EDIT: (change fully to vaguely) understand but I'm going to make an exception here as I can't imagine it can hurt anything. Notice the qualifier "believe"? If it would have been left up to me to conquer the disassembly and mapping of $EE we'd all be stuck using carburetors.

I have two bins ready to test when I get home. In one I scaled the BPW by 60% and have loaded the factory prime pulse table values. In the other I scaled it to give as much resolution as I believe is possible given the range of pulsewidths I've determined I should need. I'll be astonished if the second one starts at all, and not surprised if the first doesn't either.

EDIT2: One thing that really has me intrigued is what clocking the processors run at. The 1.5625 scalar has me confounded and I'd love to know how it was determined.

[spfautsch]

Well I ripped the big band-aid off first - flashed the most radical change first with BPW of 8600 / 0x2198. Cold start was great. Warm restart on par with I had yesterday after scaling the table raw by hand. I'll report back in a few days when / if I have a chance to tweak further.

[kur4o]

I have some insight how to get good feedback of injector pulswidth.
When you reached operating temperature remove injectors fuse and log with eehack during cranking. You will get very good reading of injector pulswidth and see if changes you made have any effect.

[spfautsch]

Thanks for the suggestion - I may give it a try if all else fails resolving the 60C restart issue. Other than the scenario where the engine has been hot and left to cool 3+ hours, it's starting perfectly. I think it's close to being too lean to start at all now.

If I can't find "perfection" through trial and error I might resort to wiring the ECT sensor line to a potentiometer along with your suggestion to help find the "magic" pulsewidth.

[spfautsch]

I don't think I'm going to tick this one off as a victory, but it's certainly better now than I was able to get to before changing the Base Prime Pulsewidth at 0x2680 and rescaling the whole Prime Pulsewidth table.

It's very odd, I can't reproduce the sluggish start unless:

1) I get the car to temp by running (hard or for a long drive) 160F thermostat mind you
2) I let it cool without touching it for around 2 hours 40 minutes (at ~85F ambient)

For whatever reason, this gets things into the opposite of a "goldilocks zone" between 135F and 144F where it wants to "meow" to life. It's starting reliabily here now with one crank so I'm going to move on to bigger and better things, but oddly if you start it at this temp and then shut it off within 1-2 seconds it will restart eagerly (presumably because the valves have been warmed). At ECT above 144 or below 135 it seems to roar to life as it did with stock injectors. Even warmer and cooler ECTs (above 146F or below 133F) are much more forgiving of AFR at startup. You have to take a ton of fuel out to get any reaction in these ranges.

So I guess what I've learned is that for a standard displacement 5.7, stick with the smallest injectors possible. Also, don't waste your time or money with chinese knock-offs.

Moving on to finishing the performance computer for tuning WOT power now. Thanks to everyone who contributed! I'm sure there will be more setbacks along the way such as the /other/ exhaust tip cracking, "quacking" and setting off the knock sensors. Thankfully I had enough argon to weld this one up too, regardless I'm going to be sending a strongly worded email to Stainless Works. :-\

[Terminal_Crazy]

For whatever reason, this gets things into the opposite of a "goldilocks zone" between 135F and 144F where it wants to "meow" to life. It's starting reliabily here now with one crank so I'm going to move on to bigger and better things, but oddly if you start it at this temp and then shut it off within 1-2 seconds it will restart eagerly (presumably because the valves have been warmed). At ECT above 144 or below 135 it seems to roar to life as it did with stock injectors. Even warmer and cooler ECTs (above 146F or below 133F) are much more forgiving of AFR at startup. You have to take a ton of fuel out to get any reaction in these ranges.


I just happened to come across this post whilst searching.
This is very similar to my issue with injectors going lean and happened at 49C to 55C. Your temps are around 56C-63C
Scott, could you check your logs to see if the injectors were leaning out at these temps?

Thanks
Mitch

[spfautsch]

I would but I don't think I have any logs of bringing the car up to temp at idle with the big injectors. I'll try to make one for you today if I get a chance.

I don't really think my issue is related but it could be. The pulsewidth I ended up at for the 56C row that was giving me the most problems was 2.23ms which I think is a bit higher than where you're seeing your O2s "flatline"?

It's been nasty cold here the last week or so. I've been freezing my behind off working on the diy-ltcc controller with the garage door open so the fumes don't asphyxiate me.

[spfautsch]

Here's a log of 11c - 73c at idle w/ ~43.5lb injectors. Definitely not seeing an O2 flatline issue like yours, but maybe there's something else that's useful to you here. Closed loop MAF tune btw.

Sorry it took so long to get this - had to spend yesterday keeping the rest of the "fleet" roadworthy as well as fixing the clothes washer. We have a saying here - if momma ain't happy, ain't nobody happy.

[Terminal_Crazy]

Cheers for that.

Is your wideband hooked up ?

It never moves, 9.32 when cold to 9.44 @73C
O2's look similar to mine. I know they are cold upto 11C there are two straight lines upto 650/750mV.
Then they start oscillating and drop down to 50/60mV at 42C
At 44C they've picked back up to 850/900mV until 60C when they go CL.
The LHS has a much more stable reading & the RHS has a much wider range.
Still it's around the 42-44 Degree mark that they choke.
Maybe they flash off once they start warming up ???

Maybe mine aren't doing anything weird.

I'm hoping the new ones will arrive tomorrow.

Cheers anyway
Mitch

[spfautsch]

No wideband - that's my A/C changing pressure as the engine compartment warms up. I doubt I will invest in one, but if I do it will be several months off.

I don't honestly pay much attention to what the O2s are doing when brought to temp idling. I generally start logging when I start it up, put it in gear and drive. As I mentioned earlier in this thread they act wholly different when brought up to temperature with load on the engine.

The right bank has shown fewer cross counts from day one, but it's gotten worse since the injector swap. I believe individual cylinder trims may have something to do with this.

[Terminal_Crazy]

That explains the stable afr then ��

Mitch

[spfautsch]

Another thing just occurred to me that will affect how my O2s are measuring at startup - air injection. Mine is fully functional. Sorry I didn't think about this sooner.

[Terminal_Crazy]

I binned mine off years ago when I swapped the exhaust manifolds.

Mitch