Bank1 unstable fuel trim

Jhill · 12-08-2022, 12:07 PM

Did you do any kind of mechanical engine checks? Compression, leak down? Sounds like you’ve done all the control side stuff swapping but you say it’s happening after an engine swap. What’s the condition of the engine? If your having a bad or weak cylinder it’s going to show more at idle than at higher RPM. I’d suspect it to have to be pretty bad to throw off the fuel trims that much and would show more running condition issues (misfire etc) but as you’ve already done all the injectors which would be the only other main thing aside from a shorted harness which again should massively show an issue.

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12-08-2022, 12:07 PM	#7 (permalink)
Jhill Track Member Join Date: Mar 2016 Location: San jose Posts: 854 Drives: 2013 370z sport Rep Power: 3385	Did you do any kind of mechanical engine checks? Compression, leak down? Sounds like you’ve done all the control side stuff swapping but you say it’s happening after an engine swap. What’s the condition of the engine? If your having a bad or weak cylinder it’s going to show more at idle than at higher RPM. I’d suspect it to have to be pretty bad to throw off the fuel trims that much and would show more running condition issues (misfire etc) but as you’ve already done all the injectors which would be the only other main thing aside from a shorted harness which again should massively show an issue.