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Long term fuel trims not changing

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Old Aug 20, 2006, 05:21 PM
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Long term fuel trims not changing

STFT, LTFT ,RPM, TPS
-9.0, -11.0, 2750.0, 18.47
,-6.0, -11.0, 2746.0, 18.47
,-3.0, -11.0, 2738.0, 18.47
-3.0, -11.0, 2746.0, 18.47
-5.0, -11.0, 2746.0, 18.47
-4.0, -11.0, 2742.0, 18.47
-2.0, -11.0, 2734.0, 18.47
-5.0, -11.0, 2738.0, 18.47
-5.0, -11.0, 2738.0, 18.47
-2.0, -11.0, 2730.0, 18.47
-4.0, -11.0, 2730.0, 18.47
-5.0, -12.0, 2734.0, 18.47

Here is an idea of what my fuel trims are running. My LTFT dont change from -11 or -12. Even when on the throttle or at dofferent loads including idle. The STFT are pretty good and stay +10-10 at idle and cruise.

I am know running PTE 780's sized at 665
latency is
4.6875 3.312
7.03125 2.184
9.375 1.368
11.7188 1.344
14.0625 .888
16.4062 .408
18.6768 .288

Any comments, recommendations greatly appreciated.
Old Aug 20, 2006, 06:07 PM
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They can take days to change. Unplug your battery if you want them to change faster.
Old Aug 20, 2006, 08:13 PM
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I am a DUMBASS!!! Thanks I dont know why I didnt do that before.
Old Aug 20, 2006, 09:52 PM
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If your STFT are around 0, then your LTFT won't move. That is the value that it will stay at. Since, yours are -11/-12, this means the ECU is taking out 11% of fuel to keep a stoich ratio.

You should scale your injectors to a larger number to shorten the pulsewidth that the ECU keeps them open for.

If you do this, keep in mind that you WOT/open loop fueling maps will need to be adjusted, too.


Eric
Old Aug 20, 2006, 10:00 PM
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I am still working on scaling my injectors. I had Denso 720's and switched to Precision 780's and made 2 different adjustments on the 780's and it already runs better than the Denso's. The Denso's I tried about 20 different settings and they suck ***.

I am going to sea tommorrow for the week so I wont get another chance to mess with it til Sat.

Thanks for the input guys.
Old Aug 21, 2006, 07:31 AM
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Keep in mind the STFT's are kinda offsetting from the LTFT's.. so the closer they are, the less they will alter.. But forcing them to reset will get you there faster..
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