Tuning with tunercat?
Thread Starter
Racer
Joined: Jan 2004
Posts: 458
Likes: 1
From: NY
Tuning with tunercat?
Hello all! If Datamaster say's I'm lean in fuel trim cell 18 (LTerm counts 140's) how would I change just that cell in tunercat? I don't understand this cell thing. I don't see cells in tunercat. Where would I go in tunercat to change one fuel trim cell?
Thanks, Ray
Thanks, Ray
Last edited by rtracy; Apr 7, 2006 at 02:07 PM.
Heel & Toe
Joined: Jan 2006
Posts: 16
Likes: 0
What do the STerm counts read? If they are in the 128 range, then the BLM's are normal (I run E85 and see 180 BLM's). If you are running 10% ethanol fuel, chances are this is fairly normal. It is doing it's job properly.
The integrator (STerm fuel trim) is the computer A/D interpretation of the O2 reading over time and cross counts. As STerm trims go up (lean mixture seen, O2 sensors below 0.45v, cross counts showing below 0.45v for x amount of time), the PCM will command more fuel to bring the STerm trim down, and BLM's will increase. The engine is NOT running lean when STerm fuel trims are at 128ish, regardless of what BLM's are. Default is a check engine light >160 for BLM.
No tuning needed, the PCM is doing its job.
The integrator (STerm fuel trim) is the computer A/D interpretation of the O2 reading over time and cross counts. As STerm trims go up (lean mixture seen, O2 sensors below 0.45v, cross counts showing below 0.45v for x amount of time), the PCM will command more fuel to bring the STerm trim down, and BLM's will increase. The engine is NOT running lean when STerm fuel trims are at 128ish, regardless of what BLM's are. Default is a check engine light >160 for BLM.
No tuning needed, the PCM is doing its job.
Originally Posted by rtracy
Hello all! If Datamaster say's I'm lean in fuel trim cell 18 (LTerm counts 140's) how would I change just that cell in tunercat? I don't understand this cell thing. I don't see cells in tunercat. Where would I go in tunercat to change one fuel trim cell?
Thanks, Ray
Thanks, Ray
Thread Starter
Racer
Joined: Jan 2004
Posts: 458
Likes: 1
From: NY
Originally Posted by Alvin
Hi,
The ECM doesn't use fuel trim cells for lookup nessisarly.. Take note of howt he car is running per MAP and RPM and look at your VE tables or MAF table if its a MAF car.
The ECM doesn't use fuel trim cells for lookup nessisarly.. Take note of howt he car is running per MAP and RPM and look at your VE tables or MAF table if its a MAF car.
I also noticed that it is at 0% TPS. The car is leaning out when I let off the gas.
Last edited by rtracy; Apr 8, 2006 at 12:39 AM.
Thread Starter
Racer
Joined: Jan 2004
Posts: 458
Likes: 1
From: NY
Originally Posted by N0DIH
What do the STerm counts read? If they are in the 128 range, then the BLM's are normal (I run E85 and see 180 BLM's). If you are running 10% ethanol fuel, chances are this is fairly normal. It is doing it's job properly.
The integrator (STerm fuel trim) is the computer A/D interpretation of the O2 reading over time and cross counts. As STerm trims go up (lean mixture seen, O2 sensors below 0.45v, cross counts showing below 0.45v for x amount of time), the PCM will command more fuel to bring the STerm trim down, and BLM's will increase. The engine is NOT running lean when STerm fuel trims are at 128ish, regardless of what BLM's are. Default is a check engine light >160 for BLM.
No tuning needed, the PCM is doing its job.
The integrator (STerm fuel trim) is the computer A/D interpretation of the O2 reading over time and cross counts. As STerm trims go up (lean mixture seen, O2 sensors below 0.45v, cross counts showing below 0.45v for x amount of time), the PCM will command more fuel to bring the STerm trim down, and BLM's will increase. The engine is NOT running lean when STerm fuel trims are at 128ish, regardless of what BLM's are. Default is a check engine light >160 for BLM.
No tuning needed, the PCM is doing its job.
Heel & Toe
Joined: Jan 2006
Posts: 16
Likes: 0
That is a touch high for it to be working properly. It should be correcting for it unless it cannot make the corrections.
Is there your base tune (OEM one) that you can jump back to to verify the problem is not tune introduced?
Is coolant temp at spec? (If LT1, 85C or so, L98 around 92-95C) If it is running warm, it will offset and push the trims up.
I'll ponder it some more. Do you have any data logs you can send? I might get some better ideas looking at it.
Is there your base tune (OEM one) that you can jump back to to verify the problem is not tune introduced?
Is coolant temp at spec? (If LT1, 85C or so, L98 around 92-95C) If it is running warm, it will offset and push the trims up.
I'll ponder it some more. Do you have any data logs you can send? I might get some better ideas looking at it.
Originally Posted by rtracy
STerm's are 130's, 140"s.
Thread Starter
Racer
Joined: Jan 2004
Posts: 458
Likes: 1
From: NY
Originally Posted by N0DIH
That is a touch high for it to be working properly. It should be correcting for it unless it cannot make the corrections.
Is there your base tune (OEM one) that you can jump back to to verify the problem is not tune introduced?
Is coolant temp at spec? (If LT1, 85C or so, L98 around 92-95C) If it is running warm, it will offset and push the trims up.
I'll ponder it some more. Do you have any data logs you can send? I might get some better ideas looking at it.
Is there your base tune (OEM one) that you can jump back to to verify the problem is not tune introduced?
Is coolant temp at spec? (If LT1, 85C or so, L98 around 92-95C) If it is running warm, it will offset and push the trims up.
I'll ponder it some more. Do you have any data logs you can send? I might get some better ideas looking at it.
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Drifting
Joined: May 2003
Posts: 1,730
Likes: 1
From: Charlotte NC
St. Jude Donor '05
If the BLM's are above 128 your lean. Take the number that your getting divide it by what you want (say 128) and multiply either whats in your VE table or MAF table at that spot by it.
Thread Starter
Racer
Joined: Jan 2004
Posts: 458
Likes: 1
From: NY
Originally Posted by Alvin
If the BLM's are above 128 your lean. Take the number that your getting divide it by what you want (say 128) and multiply either whats in your VE table or MAF table at that spot by it.
Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
Lots of resources on the web. Some are listed in the FAQ for this section.
This one I think addresses your immediate question:
http://www.customefis.com/GMEFI.html
This one I think addresses your immediate question:
http://www.customefis.com/GMEFI.html
Instructor
Joined: Oct 2000
Posts: 152
Likes: 0
From: des plaines, il
Originally Posted by rtracy
It is all low RPM and 60's MAP Alvin. So how do I know what MAF table to change?
I also noticed that it is at 0% TPS. The car is leaning out when I let off the gas.
I also noticed that it is at 0% TPS. The car is leaning out when I let off the gas.
'Deceleration Enleanment (DE)' or
'Deceleration Fuel Cut Off (DFCO)'
- say in the TC Manual or the Tuning Guides on TGO.
There are also guides there (and possibly in the Data Master Manual) that tell you how to read ALDL logs.
