Why is LTFT so high?
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Tuned
Joined: Sep 2005
Posts: 331
Likes: 1
From: Charlton, NY
Why is LTFT so high?
Truck runs fine and there are no codes but I plugged my new OBDII logger in and learned that my LTFT is nice and low at idle (+1%) but increases to a max of +20% as load increases. It is +10% at cruise. STFT bounces around zero as it should. Both banks are very similar. When I plot air flow rate from MAF vs. from MAP I see a correlation but a lot of scatter. I didn't think this truck had a MAP.
Truck is a 2005 5.4L, 50kmiles, new plugs and fuel filter at 30Kmiles.
Truck is a 2005 5.4L, 50kmiles, new plugs and fuel filter at 30Kmiles.
Thread Starter
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Tuned
Joined: Sep 2005
Posts: 331
Likes: 1
From: Charlton, NY
Any other ideas? Is there something else I should log?
Thanks
Fleet Mechanic
Joined: Aug 2002
Posts: 1,899
Likes: 29
From: Raleigh USA
Are there any codes? Do both long trims read high or just one? Can you see a graph of the O2 sensors and if so do they switch smoothly or jagged? They should look like nice smooth rolling hills.
Logistics Pro
Joined: Jan 2001
Posts: 3,740
Likes: 37
From: Central NYS
Ford typically runs a 3 x 3 grid for fuel trims. (Think of the vertical cells representing low/medium/high engine load and the horizontal cells representing low/medium/high engine rpm.) The scan tool displays the fuel trim of the cell the engine is currently operating in. It is used to minimize the engine variable that change with age/miles.
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Judd944
1997 - 2003 F150
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