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Fuel trim idle problem

  • Carstuff
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8 years 4 months ago - 8 years 4 months ago #9189 by Carstuff
Fuel trim idle problem was created by Carstuff
Protege 2.0 engine with slight spitting on idle. When put into drive it is slightly rough. Seems like fuel problem what you think based on these numbers ?
I didn't have time to put fuel guage on rail yet.
Fuel trim video
Last edit: 8 years 4 months ago by Carstuff.

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  • Tyler
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8 years 4 months ago #9200 by Tyler
Replied by Tyler on topic Fuel trim
Hey, I like the video! B)

Did you put the car in drive at around 30 second in? Watching the trims go negative, more negative, then they all zero out. :unsure: Seems like it may have quit closed loop at that point.

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  • Carstuff
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8 years 4 months ago #9201 by Carstuff
Replied by Carstuff on topic Fuel trim
The test was done in park after letting of the throttle it dropped to zero. But underload it was going negative shouldn't it be positive when demanding fuel.

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  • Chad
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8 years 4 months ago #9224 by Chad
Replied by Chad on topic Fuel trim
If you were in park, you were not under load. Try it while power-braking, or driving, and watch your O2 sensors. All O2 sensors should go FULL RICH during WOT. Fuel trims are controlled by O2 sensors. Your O2 sensors were indicating RICH while your STFT was negative. Your LTFT is zero, so I wouldn't worry about that, too much.
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right. :-)

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8 years 4 months ago #9229 by Carstuff
Replied by Carstuff on topic Fuel trim
I will try that. The problem is at idle not while driving. At idle it gets rough and gets misfire pop from exhaust once in a while. Underload it drives ok.

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8 years 4 months ago #9306 by Carstuff
Replied by Carstuff on topic Fuel trim
O2 sensor fuel trim

I tried a different scanner and took the vehicle for a drive and this is what I'm getting.

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