What is the normal percentage of the Bank1/2 Long Term Fuel Trim?

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Aug 31, 2004 | 10:06 AM

puloo

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What is the normal percentage of the Bank1/2 Long Term Fuel Trim?

So i had 2 engine codes showing bank1/2 fuel trim too lean.

They went as high as 25%. What is the normal? The dealer did a vacuum leak check and found a leaking hose which they fixed.

But i want to verify their work. They claim 7-8 % is normal.

Is this true?

Aug 31, 2004 | 10:12 AM

JasonS4+Festicle

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not sure, but a bad MAF often causes those codes to come up.

Aug 31, 2004 | 10:44 AM

DAP@EPL

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Normal per the Bentley manual is within +/- 4%. However under +/-10% is acceptable, IMO.

25% means that the car has reached its adjustment limit and can't compensate for the rich (- fuel trims) or lean (+ fuel trims) conditions.

-Dave Pramanik

Aug 31, 2004 | 10:46 AM

Ochlockonee

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7-8 is good. <12% is acceptable at the Ford dealer.

Aug 31, 2004 | 11:10 AM

Audi2ptzero

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What hose had a leak?

A vacuum leak can cause the FPR pressure line to be low and cause the car to run lean during any boost, but that will make part throttle readings go lean and idle readings go rich.