Cold start issue w/ front o2 sensor
Mar 12, 2015, 04:02 PM
#1
Cold start issue w/ front o2 sensor
So i have been trying to figure out how to resolve the dreaded cold start stalling. No luck for me.
Background on the car, its been on a tephra v7 rom since 2010. I used to live in south georgia and the car was garaged so it never really had to deal with really cold mornings until now. I retuned the car and switched to speed density last year. During this winter i have been trying to cure the cold start idle stalling. I have added fuel, tried different temps for closed loop, zero'd out the base timing trim table, etc etc.
After reviewing so many logs i have come to the conclusion that it has to do with my front o2 sensor transition. Once it starts reading and providing STFT, my idle starts to dip/stall and my AFRs go to about 17-18 sometimes leaner. Then it seems that the ecu tries to recover by adding fuel which bumps idle back up to about 1400rpm then the idle will fall back down below 950rpms and afrs will go lean and then the ecu tries to recover again. This will happen anywhere between 2-5 times but then settles out and idles fine. The colder the temps the worse it is.
As of right now my closed loop temp is set to 70*. My idle timing is set to 8* and while in open loop cold start afr is about 13.3 w/ some fluctuations.
Is there a table to manipulate the transition of my front o2. It seems that whenever it kicks in it tries to pull the fuel but kind of does it drastically. What other things would you guys recommend?
Just as a reference, we have just switched my buddies car to v7 and he is having the cold start idle dips as well. Any suggestions would be appreciated!
Background on the car, its been on a tephra v7 rom since 2010. I used to live in south georgia and the car was garaged so it never really had to deal with really cold mornings until now. I retuned the car and switched to speed density last year. During this winter i have been trying to cure the cold start idle stalling. I have added fuel, tried different temps for closed loop, zero'd out the base timing trim table, etc etc.
After reviewing so many logs i have come to the conclusion that it has to do with my front o2 sensor transition. Once it starts reading and providing STFT, my idle starts to dip/stall and my AFRs go to about 17-18 sometimes leaner. Then it seems that the ecu tries to recover by adding fuel which bumps idle back up to about 1400rpm then the idle will fall back down below 950rpms and afrs will go lean and then the ecu tries to recover again. This will happen anywhere between 2-5 times but then settles out and idles fine. The colder the temps the worse it is.
As of right now my closed loop temp is set to 70*. My idle timing is set to 8* and while in open loop cold start afr is about 13.3 w/ some fluctuations.
Is there a table to manipulate the transition of my front o2. It seems that whenever it kicks in it tries to pull the fuel but kind of does it drastically. What other things would you guys recommend?
Just as a reference, we have just switched my buddies car to v7 and he is having the cold start idle dips as well. Any suggestions would be appreciated!
Last edited by vmrevo9; Mar 12, 2015 at 11:10 PM.
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