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Discussion Starter #1
Could someone give me an insight into fuel trims.

At my last MOT i was advised that the car is running rich

since then i bought an OBDII with live data to see what was happening.

I've plugged it in to find:-

Short term fuel trims - both banks running between 1 and 5%

long term fuel trims - static at -53.9%

I was expecting a high reading with a possible cause of leak within the inlet.

Any ideas why -53.9% and due to both banks being the same i am wondering if it has maxed out
 

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If your gas is rich, the ecu will decrease the trim to allow for it. When you run on petrol the trim will be way out so hence runs badly. Get the adaptions reset and get the lpg tuned.
 

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Discussion Starter #5
Thanks Rewmer,

Am i correct in saying the short term trims shows what is happening now, and if so the readings of 1 and 5% are adding more fuel.

Whereas the long term fuel trims are showing negative figures (wanting to take fuel away)

Based on this i tried a new maf, to see if it had different figures, which immediately brought the short term fuel trims down to a negative (-3 to -7%)

Again am i correct in saying this will remain a negative for quite a while until the the ecu has time to relearn the correct maf readings or to speed up the process book it in for the adaptions to be reset?

I plan to keep it on petrol until i can get the LTFT and STFT stable before i get the gas reset.
 
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