Re: Lean Misfires at 2700-2800 rpm
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Originally Posted by TurboBob
The O2 trim hitting 160 and then dropping is a huge indicator of whats going on.
The short term trim is running out of adjustment range, and the ECU is "defaulting" or something. Watch the O2 trim just before it starts to act up and see if it is climbing with RPM.
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I'm sorry, I should have been more specific when I said it hits 160. I'll be cruising along, at an O2 trim between 80-100 and as soon as I get to the point(s) (I have 2 points now in the 2600 - 3200 rpm range), it misfires and the o2 trim spikes up to 160 and then back down between 80-100. If I stay at the same RPM point it'll do it constantly and the o2 trim will bounce back and forth.
I've tried richening up the mix, so that when I hit those points I'm cruising at an O2 trim of 60-70, but it still misfires and it still spikes up to 160 and then back down to 60.
Since the O2 trim spikes to 160 seem to happen regardless of how rich the tune is during closed loop, I have a feeling the spikes to 160 are a result of the misfire and not the cause, but then again, this is only a hunch. It seems like it would make sense though, with all that unspent air being dumped into the exhaust, the o2 sensors would read lean. I just can't think of what could be causing the problem. You'd think it would have to be something that partakes in the closed loop fuel adjustment, but what??
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'91 VR4 - Modlist: DR650R turbos, Snow stage 2D alky kit, DSM SMICs, blowthrough ported LT1 MAS, Dejon Tool intakes & y-pipe, Blitz DSBC Spec R, HKS SSQV BOV, PTE 580cc injectors, Dual feed fuel system with Aeromotive FPR & filter, Hotwired Supra pump, HKS DLI, MSD Wires, Apex'i S-AFC II, MAFTranslator, Turbobob ECU, Scanmaster III, LC-1 WBO2, ESP downpipe, Vac/EGR delete, Gutted precats and test pipe, Maximal solid mounts, 300m 18 spline output shaft, Centerforce Dual Friction clutch, RPS flywheel, GC coilover conversions with helper springs, Powerslot slotted rotors, Goodridge SS brake lines, Hawk pads (front), Stillen metal matrix pads (rear)
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