Rising Air fuel ratio 21:1

[Guzman08]

ok so when i turn on the car it starts up fine then the air fuel ratio rises all the way up to 21. i then locked it in open loop mode and it went down to about 13-14.and sounded much better. what could be the problem. i used dsmlink to get this info. check it out . idk how to attch a log on here.

ECMTuning User Support Forums

 

[twdorris]

I don't see any wideband data in your log, so I'm going to assume you're looking at the estimated A/F ratio in ECMLink. If so, you have to keep in mind what that's showing you. It's showing you what the ECU is trying to achieve.

When you have things dialed in properly, the estimated A/F ratio will match measured almost perfectly. Until then, you have to understand that it's really just showing what the ECU is trying to achieve.

So why is the ECU trying to achieve a 21:1 A/F ratio? Because it believes the actual mixture is extremely rich, so it's trying to lean it out for you.

And why does it think that? Because your front O2 voltage is bogus. It's starting at 3.8v and dropping slowly to around 1.5v, but that's still WAY outside the range a factory O2 sensor can produce.

You've got something attached to the front O2 signal coming into the ECU that the ECU is not configured to accept yet.

I would normally think you have a wideband kit wired in there, but the signal shape does not seem to agree. It's a very smooth, slow arc that does not seem to reflect anything related to the engine's operation. It doesn't track what the ECU is trying to do with mixture and it doesn't track any of the temperature data or MAP sensor data either. It's truly a bizarre signal.

Thomas Dorris

 

[twdorris]

Since some people may not be able to view the logs, I thought I'd throw this together to illustrate what I'm seeing.

 

[Guzman08]

well i have an air fuel gauges that was already in the car. it comes off and on but i dont really pay attention to it. would this be causing a problem. ? i am going to check it out right now anyways

it goes by date. the last one was when i switched the o2 sensor. what do u guys think

 

[Guzman08]

ok .. now that i am at home i can type right now. ok so i put the car in open loop so i ca drive it all the way home. did not overheat , went up and stayed at 200F. idk if thats to high but thats where it was. the af ration was around 13-14. then i took it off open loop and put it on normal. th air fuel ratio went high, 16-18 and above. idk if i have to do that adjustment tht u said first or if its something else. here are two logs i took. one with closed loop and the other open. tell me what u think. and what kind of run would i make so i can do that combined ft adjustment??



the car overheated when i was driving yesterday, the air fuel ratio was 16+ would go up high. drove it on closed loop all the way home. works good on closed loop.