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Misfire over 10psi - Possibly load related misfire?


edviss

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Hi All,

2jz non vvti NA-T

I thought I will open a thread in case someone had a similar issue.. as after months of looking still no luck.

Below I have attached a graph from EcuMaster log. 2nd gear looks pretty clean, but once I change to 3rd it start to misfire straight away, 2nd and 3rd gear both in same boost 175kpa mark.

I dont get any misfire below 10psi of boost.

image.png.e6b0fc6c15fd11b5ab74c980f6407e85.png

Parts I have changed:
Injectors - 715cc bosch ev14
Coilpacks -  yaris smart coils
Fuel Pump - walbro 450lph + Relay mod
Spark Plugs - bkr7eix and bkr8eix
Fuel Dampener Removed
BC valve springs and bsc stem seals

On high boost ECU and engine is not loosing any voltage or fuel pressure.  Compression on all 6 cylinders is good.

Things like changing dwell time, gapping spark plugs, changing map and etc have been tried. 

It kind a feels like it is more mechanical than electrical issue, engine get higher load in 3rd gear and starts to misfire? but what could cause that 😕 

Any suggestions welcome! 

 

Thanks,

Ed


 

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What are you using for cam/crank signal?

Same thing happened to me but I never found out the root cause...blew the car up and melted 5 pistons before getting to the bottom of it. I'd changed pretty much everything you've changed as well and it only pushed the misfire higher up the rev range. My misfire started in second gear but I'm V161, so it's probably in the same region as 3rd in a W58.

I was still on a distributor at the time and my only remaining suspicion was that the dizzy was on it's way out and not communicating with the ECU properly. Maybe as a result, timing wasn't where it was meant to be and ultimately lead to the misfire.

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