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Old 06-17-2016, 02:38 PM   #1
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Default Stock ECU Fuel Trim Issue

Long story short, swapped a 00' JDM 1.8 into my 00' and using the factory ecu until I get my megasquirt configured for a NB (moving over from a 95') I'm seeing LTFT in the plus 20% range and STFT is pegged at -25%. Just trying guage the health of the motor until I get the MS2 on it. What would cause this? Currently the only codes are for the lack of a secondary O2 sensor.
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Old 06-18-2016, 11:18 PM   #2
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So 125 views and no comments, I know this is an odd question. Here's some more data to ponder on. The JDM motor has a BP5A intake cam (AKA MSM cam), it also has a tubular exhaust manifold that I'm using that is very similar to the 02+ cars. So everything points to this motor moving more air than the original motor, being that it's still a MAF car it shouldn't matter. Any kind of leak between the intake and the MAF would result in a lean condition not rich. I highly doubt I have a high fuel pressure issue so what else could cause a motor to run rich?

The only thing i can think of is that there was some salt induced corrosion on the exterior of the motor ( shipping in a crate on a boat I assume) so maybe the O2 sensor is fubar? The original O2 was exposed to a ton of oil burn so I wouldn't trust it either.

I couldn't care less but if there is an issue with the motor I don't want to waste time with the MS tuning around it. Have a DIYPNP MS2 and a WB that will eventually make it's way on to the car.
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Old 06-19-2016, 10:51 PM   #3
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Sticking injector, vacuum leak, biased o2.


Negative trim means the car is pulling fuel. If it drives normally, no misses, I'd be looking at the O2.
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Old 06-19-2016, 11:20 PM   #4
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Did you clear the trims when you installed the engine?
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Old 06-19-2016, 11:33 PM   #5
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Quote:
Originally Posted by curly View Post
Did you clear the trims when you installed the engine?
How would one go about this? A simple power cycle do it?
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Old 06-20-2016, 01:12 AM   #6
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Obd2 scanner will do it. You currently have a +5% fuel trim, sounds like it'll even itself out eventually. with a new engine you need to start zerod out though, not with the long term trims from the old engine.
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