TBI Tuning for dummies?

[IamBrad]

Hi all, I'm totally new to the TBI tuning (or tuning in general) and I'm just trying to figure out the basics. I've been reading a lot of different threads and post but they all seem to assume that you already have an understanding on why you do certain things. So, I'm wondering if anybody has any links to information on why we tune certain things and what are the items you want to start with. I'm not trying to be a pro or tune a race car. I just want to have enough of an understanding on how to adjust my tune and optimize it for some changes such as a new cam, exhaust, TBI mods etc. as I make those changes.

Here is where I am now. I've got the Moates Burn 2 and G1 adapter. I've figured out how to read the bin off my stock chip, how to load that into Tuner Pro along with all the definitions etc. and how to then burn the bin back to a new chip.

So, my question now is where should I start and what things should I look at? I'm not necessarily looking for how to do things. I'm pretty sure can find that on the interwebs once I know what I'm looking for. I'm mostly looking for the what and why.

I see a lot about VE tuning. Is that where I should start? I've read that spark advance is one of the later things you should work on. Also, why is VE tuning so important if the PCM already adjusts fueling based on O2 sensor readings?

What would be the next things to look at after VE?

Thanks for any help.

[dave w]

Perhaps a brief description of what your tuning will help. Year / Make / Model / Engine / Transmission / ECM or PCM information.

That helps with knowing what TunerPro files are to be used. Then the uphill fun begins.

dave w

[stew86MCSS396]

I see a lot about VE tuning. Is that where I should start? I've read that spark advance is one of the later things you should work on. Also, why is VE tuning so important if the PCM already adjusts fueling based on O2 sensor readings?

What would be the next things to look at after VE?

Thanks for any help.

Since you alluded that you don't need a tutorial...you need to adjust your VE tables so your datalogs return BLMs of 128+- 3. There's going to be "events" in the PCM i.e. power enrichment (PE) where the PCM locks the BLMs at 128 then provides additional fueling/timing etc so having your VEs adjusted to return a BLM of 128 is desirable.

[IamBrad]

Perhaps a brief description of what your tuning will help. Year / Make / Model / Engine / Transmission / ECM or PCM information.

That helps with knowing what TunerPro files are to be used. Then the uphill fun begins.

dave w

It's a 1994 C1500 with a 305 and 4L60e. the PCM is 16196395 and the bin is BHMD. The engine is stock. I did add some shorty headers, high flow cat and did the Ultimate TBI mod. I did add a TBI spacer but that was more to be able to clear the distributor after removing the collar that the TBI units have.

Future upgrades will be a mild roller cam .447/.459 lift with 201/208 duration. I have some 081 heads also with larger intake values but I'm not sure I'm going to use them yet. Because I'm more interested in low end torque than high end HP.

[IamBrad]

Since you alluded that you don't need a tutorial...you need to adjust your VE tables so your datalogs return BLMs of 128+- 3. There's going to be "events" in the PCM i.e. power enrichment (PE) where the PCM locks the BLMs at 128 then provides additional fueling/timing etc so having your VEs adjusted to return a BLM of 128 is desirable.

Right there are already good tutorials out there like the one from EagleMark. But what I'm trying to figure out is why are we doing this. What does adjusting your VE do to the engine.

Does it create more power or just make it run smoother?
What is the goal of the VE adjustment? Does it make it easier for the PCM to adjust for stoic mixture if your VE is adjusted correctly or is there another reason to do it?
Should VE be adjusted before other factors?
How does PE Factor into this?
At what point do you try and adjust PE.
Are there other things to l should look at before this.

Of course to make it harder I'm trying to find something in normal English and not super technical jargon.

[dave w]

It's a 1994 C1500 with a 305 and 4L60e. the PCM is 16196395 and the bin is BHMD. The engine is stock. I did add some shorty headers, high flow cat and did the Ultimate TBI mod. I did add a TBI spacer but that was more to be able to clear the distributor after removing the collar that the TBI units have.

Future upgrades will be a mild roller cam .447/.459 lift with 201/208 duration. I have some 081 heads also with larger intake values but I'm not sure I'm going to use them yet. Because I'm more interested in low end torque than high end HP.

I'm slightly confused, 16196395 is usually $OE definition for a 4L80E : http://www.gearhead-efi.com/Fuel-Injection/showthread.php?337-16196395-PCM-Information-OE

What I was able to find is BHMD is listed for $OD 16197427 : http://www.gearhead-efi.com/Fuel-Injection/showthread.php?303-16197427-PCM-Information-0D

There is information showing the 16196395 will work with $OD BHMD, but I don't have personal experience to verify 16196395 will work with $OD BHMD. Perhaps using 16197427 would be an option?

The overriding factor is BHMD is $OD, so tuning with $OD is the path forward.
TunerPro RT File Type: adx A217 $0D TP5 v250.adx
TunerPro RT File Type: xdf Advanced $0D TP5 v251.xdf

[IamBrad]

I'm slightly confused, 16196395 is usually $OE definition for a 4L80E : http://www.gearhead-efi.com/Fuel-Injection/showthread.php?337-16196395-PCM-Information-OE

What I was able to find is BHMD is listed for $OD 16197427 : http://www.gearhead-efi.com/Fuel-Injection/showthread.php?303-16197427-PCM-Information-0D

There is information showing the 16196395 will work with $OD BHMD, but I don't have personal experience to verify 16196395 will work with $OD BHMD. Perhaps using 16197427 would be an option?


Haha you and me both. It took me about a day to figure that out. Everything was telling me it should be $0E and that it was only used in HD trucks with the 4L80E. But I guess GM didn't pay attention to that. Anyway the $0D stuff seems to work well. :thumbsup:

[dave w]

Next step is to post a data log. Advanced tuners often use Air Fuel Ratios to tune with: http://www.gearhead-efi.com/Fuel-Injection/showthread.php?5381-WBO2-Tuning-Spreadsheet

[mihela]

8625, 7427 and 6395 are mostly interchangeable and all can run $0E, $0D, and $31 code. $0D is for a 4L60E, $0E and $31 are for the 4L80E. I would start with the latest 1995 code for your truck combination as a base for your tune and work from there. Do you have a wideband? It's possible to tap its 0-5 volt output to the EGR position sensor wiring and hack it into the datastream in place of battery voltage. Then you can feed the datalog into a spreadsheet to help you tune the VE table. That's more accurate than BLM tuning.

[In-Tech]

8625, 7427 and 6395 are mostly interchangeable and all can run $0E, $0D, and $31 code. $0D is for a 4L60E, $0E and $31 are for the 4L80E. I would start with the latest 1995 code for your truck combination as a base for your tune and work from there. Do you have a wideband? It's possible to tap its 0-5 volt output to the EGR position sensor wiring and hack it into the datastream in place of battery voltage. Then you can feed the datalog into a spreadsheet to help you tune the VE table. That's more accurate than BLM tuning.
If your transmission is a '94 DON'T use a '95 file, the transmission changed in '95.:nono:

[ras"86]

Where can I find what transmission are interchangeable?

[In-Tech]

Hiya, for the TBI trucks the '93/'94 4L60E trans can interchange. From memory, the '95 up went to PWM TCC controls. I believe this can be changed in the .bin file. It's been a long time since I looked at all that stuff. Hopefully someone can chime in with better memory than me :)

[ras"86]

Thanks, trying to find a replacement for a 98 1500 for a friend.

[mihela]

For the 4L60E, yes. good point. I'd break one of those like a twig.

[IamBrad]

Where can I find what transmission are interchangeable?

There was a good video on YouTube I found a while back. Don't hold me to it but from what I remember the model years that are the same are 93-94, 95 (single year only), 96-99. After that I stopped paying attention.

[ras"86]

Thanks hard to keep somethings straight

[IamBrad]

I found this PDF which I found very helpful in giving a very basic understanding of tuning the GM EFI. So, I figured I'd post it here for anyone who might stumble onto this thread. It answered a lot of my questions and had really good explanation. It's for an older mask so not fully relevant but the explanations of the different functions is very helpful.

https://www.gmcmi.com/wp-content/uploads/2014/05/How-to-Tune-a-GM-EFI-System.pdf

It looks like the authors website is no longer around. Which is a shame, it would have been nice to find some more of his write-ups.

[IamBrad]

It's been pretty busy so I have not had much time to datalog. I got one log in the other day. I adjusted the VE maps based on this and will try and get another log going.

[dave w]

Screen Captures from Data Log 1.xdl

18047

18048

18049

[IamBrad]

Screen Captures from Data Log 1.xdl

18047

18048

18049

Thanks. So, I get the BLM numbers in the top section and I have the spread sheet to adjust those. But what are the numbers in the green section?

I'm also curious about the spark advance you've circled. I've seen that while playing back the data log. But I was not sure what was causing that since they are unrealistic numbers. I think that range of RPM vs MAP is where I'm seeing knock so, I don't know if that's what's causing the data to spike like that. I did retard the advance a little in those areas where I saw knock.

I have not messed with the spark advance at all other than turning it down 1-2' in the areas where I saw knock retard.

[IamBrad]

I was watching my second log file it looks like the spark advance spikes at tip in. Again, I'm not sure if this is just an issue with the data log or something real. But here are screen shots of the dash board right before and during. Dash 0 was a few seconds before (I think I was sitting at a light), Dash 1 is the frame right before and Dash 2 the first frame when it started. The advance spiked for maybe 3-4 frames and then went back down. I don't really see anything out of sorts. Anybody have any thoughts?

[dave w]

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?7226-Weird-OD-Spark-Advanced-FIXED-sorta

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?8460-23037*-Spark-Advance&

18057

[ralmo94]

I have a '94 GMC with a 6395 $OD stock. So they are not 4l80 specific.
95 model year introduced PWM controlled TCC. run the bin that matches your transmission.

VE, or Volumetric Efficiency, is in simple terms, how much air your engine fills the cylinders in a certain condition, IE load and RPM.
That is Speed Density Fueling. Certain Amount of air requires certain amount of fuel. Systems can self tune to a degree with O2 input, but any time you loose battery power you are back to square 1. And also, they are not that accurate, in this generation of computers, they are made to fine tune, not compensate for large airflow changes. That is why you change VE to tune the lookup table. That is the why. I would highly recommend a Wide band o2, for tuning a cam change. I have a tutorial on how to tune open loop with one in the writeup section.

[Sledhead2]

I found this PDF which I found very helpful in giving a very basic understanding of tuning the GM EFI. So, I figured I'd post it here for anyone who might stumble onto this thread. It answered a lot of my questions and had really good explanation. It's for an older mask so not fully relevant but the explanations of the different functions is very helpful.

https://www.gmcmi.com/wp-content/uploads/2014/05/How-to-Tune-a-GM-EFI-System.pdf

It looks like the authors website is no longer around. Which is a shame, it would have been nice to find some more of his write-ups.


I am a green horn regarding tuning, I have to ask admin if this tuning 101 paper would be something helpful to save into the "GM ECM - Bins - TunerPro Definition Files - Wiring Diagrams - Tuner Info!" section? maybe call the folder "basic 101 tuning or heck even call it "start here"

[IamBrad]

I would highly recommend a Wide band o2, for tuning a cam change. I have a tutorial on how to tune open loop with one in the writeup section.

WB is definitely on the shopping list. Just trying to figure out which one to go with. Right now I'm leaning towards the AEM 30-0300 because the price point seems decent. I'm also considering the Innovate LC-2 controller with gauge.

[dave w]

The AEM 30-4110 https://www.aemelectronics.com/products/gauges/wideband-uego-air-fuel-gauges/digital-wideband-uego-afr-gauge/digital-wideband-uego-afr-gauge is Plug-n-Play if using the WBO2 - Tuning Spreadsheet: http://www.gearhead-efi.com/Fuel-Injection/showthread.php?5381-WBO2-Tuning-Spreadsheet



0-5v analog output (10-20 AFR range only)

[IamBrad]

Decided to go with the AEM 30-4110 should hopefully be here this weekend. Whether or not I'll have time to install it is another question.

I am seeing a lot of fluctuations in my BLM readings which is making it really hard to get this down. I did a 30ish mile log yesterday on my commute to work ranging from stop and go traffic to 80mph. Some of the cells saw swings of 12-19 points between the low and high BLM values. So, I'm really curious what the WB will end up showing. I'm also wondering if this could be caused by my NB. I do have a new one sitting on the shelf so maybe I should drop that in and see if it makes a difference.

Edit:
To add to the above, I also wanted to see if may certain things like PE were effecting the results. So, I did an export of the log to Excel and removed all records with PE or Open Loop enabled to see if that would reduce the fluctuations. It changed the averages slightly but still saw large fluctuations in regions with a lot of samples.

[dave w]

The WBO2 spreadsheet I posted a link to will filter out PE, AE, and Open Loop data in the cell averages. The WBO2 spreadsheet is for Closed Loop Only tuning.:thumbsup:

It's not unusual to have BLM swings. As the BLM / AFR tuning progresses, the BLM / AFR swings will be present but less. It's impossible to ZERO Out the swings.

[IamBrad]

The WBO2 spreadsheet I posted a link to will filter out PE, AE, and Open Loop data in the cell averages. The WBO2 spreadsheet is for Closed Loop Only tuning.:thumbsup:

It's not unusual to have BLM swings. As the BLM / AFR tuning progresses, the BLM / AFR swings will be present but less. It's impossible to ZERO Out the swings.

I've got that thread saved and will be reading through it. Good to know about the BLM swings.

[IamBrad]

The AEM 30-4110 https://www.aemelectronics.com/products/gauges/wideband-uego-air-fuel-gauges/digital-wideband-uego-afr-gauge/digital-wideband-uego-afr-gauge is Plug-n-Play if using the WBO2 - Tuning Spreadsheet: http://www.gearhead-efi.com/Fuel-Injection/showthread.php?5381-WBO2-Tuning-Spreadsheet


Ok, so I was playing around with your spreadsheet and I have some questions. Not so much about the main functionality of the spreadsheet. I think I've figured that out and it's pretty straight forward. The one functionality question I do have is. I see where you have a table for PE Active AFR however, I don't see anywhere that this is used to create an adjustment for the VE map. Is there a different spreadsheet where this is used?

My other question and please keep in mind this is coming from a Excel/Data geek and not a tuner. Is there a reason you are using the Fixed AFR for Closed loop only rather than using the Desired AFR input which would appear to also work with open loop and PE data and allow you to move into the higher RPM ranges as well. Functionality wise it seems like an easy switch since the desired AFR data is already there. Just insert another table populate it with the Desired AFR and compare that to the WBO2 data. I guess if the issue is related to closed loop data you could use this of the Open Loop and PE data.

Anyway, nice work on the spreadsheet.

[dave w]

Ok, so I was playing around with your spreadsheet and I have some questions. Not so much about the main functionality of the spreadsheet. I think I've figured that out and it's pretty straight forward. The one functionality question I do have is. I see where you have a table for PE Active AFR however, I don't see anywhere that this is used to create an adjustment for the VE map. Is there a different spreadsheet where this is used?

My other question and please keep in mind this is coming from a Excel/Data geek and not a tuner. Is there a reason you are using the Fixed AFR for Closed loop only rather than using the Desired AFR input which would appear to also work with open loop and PE data and allow you to move into the higher RPM ranges as well. Functionality wise it seems like an easy switch since the desired AFR data is already there. Just insert another table populate it with the Desired AFR and compare that to the WBO2 data. I guess if the issue is related to closed loop data you could use this of the Open Loop and PE data.

Anyway, nice work on the spreadsheet.

Honestly, I never considered using Desired AFR. I consider AFR as a measurement, and configured Excel to tune based on what is being measured by the WBO2 meter.

$E6, $OD, $31, and $OE have tables for PE (MAP vs. RPM vs. TPS). The PE data in the spreadsheet provides "clues" for adjusting the PE tables.

Sometimes the spreadsheet is repurposed for Open Loop tuning by changing all Open Loop / Closed Loop Column values over to Closed Loop.

Intermediate and advanced Excel users will often "Sort" data to find data like AFR when AE is active only.

I often joke with gearhead-efi members. . . there is Power in the Excel spreadsheet.:innocent2:

[IamBrad]

I often joke with gearhead-efi members. . . there is Power in the Excel spreadsheet.:innocent2:

There definitely is. Excel is kind of my thing. There is so much you can do with it. I've been using it daily for 15+ years and I still learn new stuff all the time. So, I like the idea of doing more with it. I already had some ideas just from playing around with one of the data exports. But, your template has given me some more ideas. I'm still in the middle of year end at work so, it's a bit busy right now. But, once I have some more time I plan to play around with it and see what else I can do. In addition to trying the comparison to desired AFR I'm also thinking about maybe playing with some dynamic filters that will allow you to toggle between open and closed loop data by using a drop down.