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Topic: Short term fuel trims. (Read 903 times) |
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twinturbo
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24V's Me game!
 
Posts: 904
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Short term fuel trims.
« on: Oct 14th, 2006, 7:33pm » |
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Right, still trying to get to the bottom of my lumpy idle..
I swapped over the MAF today for another one ( no history ) and the car ran exactly the same. If I desconect the maf the car pics up a bit but then still struggles.
I monitored the fule trims, and the STFT on Bank two was more often in the -% often hanging around -14% . It would rise above ZERO when the throttle was depressed.
Now is a negative % Week mixture or rich Mixture?
Bank 1 was generaly + but dipping ocasionaly negative.
TT
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Havinga
Newbie
1998 2.9 24v Ultima est, 96 2.0 16v ultima saloon
Posts: 44
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Re: Short term fuel trims.
« Reply #1 on: Oct 14th, 2006, 11:06pm » |
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Hi,
Firstly id have a good look for an air leak and disconect the EGR
spray carb cleaner round the inlet manifold, one joint at a time and see if the idle speed increases.
Check the vacuum tees and inlet o'rings are fav for leaks.
Check the vacuum, shoud read about 20-22 with a gauge.
I'd be tempted to ignore stft and watch the Long term trims and o2 sensors (pre cat) along with TPS and MaF.
What are they doing?
As i understand it if a trim shows neg, it's trying to lean the mixture off, Dont take my word for it I could be wrong!
Best of Luck.
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twinturbo
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24V's Me game!
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Re: Short term fuel trims.
« Reply #2 on: Oct 15th, 2006, 8:28am » |
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If I had a leak the mixture would be week so surely the trim woul be trying to enrich?
I do think I have a leav on the back passenger plenum joint ( the sleved one..
TT
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