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Old 11-09-2019, 05:53 AM   #1
kev0
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Anyone have an idea why my car is only lean during cold starts?

https://datazap.me/u/kev0/high-trims?log=0&data=21

Fuel trims are max positive during cold starts, but normalize after a few minutes of driving. Why is that? Is it in the tune or is something physically wrong with my car? Pressure tested and smoke tested got nothing. Haven't checked the header for leaks, but I doubt it's an exhaust leak because this only started happening after I boosted my car.

As you can see from the log, my fuel trims are within normal operating range towards the very end of the log. I've read about exhaust leaks but from my understanding, fuel trims only become normal when you're on throttle and will begin to max out again when idling/off throttle. This isn't the case with me. After the initial warm up period, my fuel trims stay within normal operating range. I'm left scratching my head as to why this is.


Tuned with Ecutek and on E85 with a Flex fuel kit.
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Old 11-09-2019, 08:38 AM   #2
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Im not a expert in software or electrical, but could it be trying to lean out so the engine can get to operating temp cause you're 1. You're boosted 2. on e85. cause doesn't e85 ignite cooler so the engine operates at a cooler level when driving ?

Thats my guess i could be wrong lol
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Old 11-09-2019, 09:00 AM   #3
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It normal it’s part of the cold start warmup routine

If you reduce the Maf offset after start tables it will reduce this effect both tables in neutral and in gear
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Old 11-10-2019, 06:15 AM   #4
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It normal it’s part of the cold start warmup routine

If you reduce the Maf offset after start tables it will reduce this effect both tables in neutral and in gear
The max positive fuel trim during cold starts throw a P0171 code for me. I clear it but it will come back every 2-3 days because of the cold starts. I can't edit the ecutek tune because I dont have the version to edit tunes. My tuner does all the work. My tuner still doesn't know why my fuel trims are applying so much correction during cold starts.

Forgot to mention that I have an automatic, if that matters.
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Old 11-10-2019, 10:42 AM   #5
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Quote:
Originally Posted by kev0 View Post
The max positive fuel trim during cold starts throw a P0171 code for me. I clear it but it will come back every 2-3 days because of the cold starts. I can't edit the ecutek tune because I dont have the version to edit tunes. My tuner does all the work. My tuner still doesn't know why my fuel trims are applying so much correction during cold starts.

Forgot to mention that I have an automatic, if that matters.

once your blue light turns off and its heated up and you then idle it still does this or is it back to where it should be?
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Old 11-10-2019, 05:11 PM   #6
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Originally Posted by kev0 View Post
The max positive fuel trim during cold starts throw a P0171 code for me. I clear it but it will come back every 2-3 days because of the cold starts. I can't edit the ecutek tune because I dont have the version to edit tunes. My tuner does all the work. My tuner still doesn't know why my fuel trims are applying so much correction during cold starts.

Forgot to mention that I have an automatic, if that matters.

Sounds like you goy some other problems as well if your trims are that far out. Possibly leak or bov issue.


Most ecutek tunes are locked to tuner, so you cannot edit regardless of the levle of ecutek access you buy
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Old 11-10-2019, 06:25 PM   #7
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Originally Posted by steve99 View Post
Sounds like you goy some other problems as well if your trims are that far out. Possibly leak or bov issue.


Most ecutek tunes are locked to tuner, so you cannot edit regardless of the levle of ecutek access you buy
Possibly might be a leak but not sure how my fuel trims would normalize after a few minutes instead of having consistently high trims, no matter how warm the car is.

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once your blue light turns off and its heated up and you then idle it still does this or is it back to where it should be?
My model year is 2014 so I don't have those fancy lights that you have, but idle is fine once car is 'warmed up'
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Old 11-10-2019, 09:29 PM   #8
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I'd go with exhaust manifold leak that seals up as things expand. But usually you would hear that...
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