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Disable ltft

Practical Reflash Tuning

Discussion and questions related to the course Reflashing


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I have never heard this before. Gas quality in Ohio is all over the place, I watch my trims and lambda pretty close. It’s common for one bank of my 5.2 v8 voodoo to eventually trim out 4 to 5 percent over the other bank in most operating ranges past idle. Stock injectors on e50. Had a clogged injector once max the stft to plus 18 percent on that bank. Even now with perfectly clean stock injectors they are not equal, bank wise (4 cylinders per bank). On 93 octane difference is much less so mechanically I think I’m fine. Seems like I have a lazy injector. Can stft react fast enough?

Actually stft will be disabled in open loop, so I guess the question is, if I know I have bank to bank discrepancies in afr, can I responsibly disable ltft. WOT will be worse. Stupid OEM ECU don’t throw error codes until fuel trims are like 20 to 25 percent off. I also have brand new plugs and wide bands. Both replaced at 20k miles.

If you turn off long term fuel trim your engine will have no way of compensating for variations in ethanol concentration as you fill up, and your short term fuel trims could potentially peg. It's not a bug, it's a feature.

There will always be cylinder balance issues on any engine with 2 banks, even a flat plane V8.