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        General >> Problems >> Lean term fuel trim
        
(Message started by: Kenboy on May 5^th, 2004, 6:40pm)

Title: Lean term fuel trim
Post by Kenboy on May 5^th, 2004, 6:40pm

Hi Whilst at derby I had an obd scan that revealed a fault , unfortuanately I did not rec ord the error number but it was explained to me that -10.9% lean term fuel trim indicates that the car is running rich? The maf is spotless and the only other problem to my knowledge is that the fuel cut off loom has been tempory repaired as aresult of insulation perishing, wethet or not this causing the problem is only speculation and scorpio man suggested I post this thread for maybe the experts to come up with suggestions while I am on this subject is should I treat this fault with some urgency and what damage can it potentialy do.

Regards Kenboy

Title: Re: Lean term fuel trim
Post by Eric_R on May 6^th, 2004, 12:08am

Ken,
The Long Term Fuel Trims are explained in http://www.fordscorpio.co.uk/fuelmonitor.htm.
An excessive lean trim is indeed because the combustion is too rich. This can be caused by electrical faults in the loom, corrosion in connectors, leaking INJectors as well as over-pressure in the fuel rail caused by a faulty fuel pressure regulator.
An obvious problem is the Fuel Cut Off Loom - and I would take steps to change that asap. You should eliminate this as the cause before you start experiencing starting problems.
This is shown on http://www.fordscorpio.co.uk/dohcloom.htm

In the meantime you are using more fuel than you need to and in the long term you might be doing your catalyst(s) no good so don't delay too long.

Title: Re: Lean term fuel trim
Post by Kenboy on May 6^th, 2004, 1:04pm

Thanks for the advice, wil replace loom next payday.

Regards Kenboy