1JZ Misfiring Issues - Tried Everything

Backwoodsballer

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Hey Everyone
I posted this thread in SupraForums also but i have not gotten any replys, i am hoping i might have better luck here:

I am looking for some advice on my issue, I have done tons of research and tried everything that i could think of to solve this but nothing has helped.

Basically what is happening is that my car experiences misfires only after it is fully warmed up. If i drive the car during the warmup cycle it runs like a dream, but once i hit the point where the car is fully warm it starts to miss badly. The Misfires occur during idle, cruise speeds, and boost, sometimes to the point where i cant even drive anymore, i need to pull over and let it sit. The worse part about this diagnosis is that occasionally after it is warmed up i can get a full pull in without any breaking up. Engine Temps are perfect also.

With that said i am lead to believe that it is a sensor/ Electronic issue. Also the car ran mint after the swap for about 1.5 years and this just started happening before winter.

My Setup:
Stock ECU
Stock Injectors
Adjustable FPR (35psi with Vacuum)
Walboro 255 Fuel pump
GT35 Turbo
Tial Wastegate (12psi Spring Pressure)
NGK 4644 Plugs
Wiring Specialties harness - Brand New

What i have Tried so far:
-Opened the ECU - No Blown or leaking Capacitors at all
-Spark Plug Gap - Started at .025 and worked down to .020, nothing helped
-Boost leak test - Checked all vacuum lines and sprayed brake clean throughout and there was no change in idle speed
-Coil Packs - 5/6 were cracked so i put in 6 brand new Bosch coil packs - did not help
-Brand new Coolant temp sensor was put in when i did the swap


I also have a brand new Igniter on the way to rule that out (there no 2jz or 1jz cars local to me to test theirs and i did not want to buy a used one)

Any Help or ideas would be greatly appreciated.
 

Backwoodsballer

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Yeah my air fuel is perfect when the car is running. I am using an AEM EUEGO as my gauge.

Because I can’t stop fiddling when something is broken I decided to run though the main sensors.
As I got to the cam sensor I noticed there was oil on the top of the plug. I proceeded to unplug the connector and the plug on the cam sensor was FILLED with oil.
I ordered a new sensor and cleaned up the plug. Hopefully that was my problem. I will update this once I am able to test the new sensor.

Has anyone ever heard of this happening? It certainly seems like this might be my culprit
 

seoul4korea

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Yeah my air fuel is perfect when the car is running. I am using an AEM EUEGO as my gauge.

Because I can’t stop fiddling when something is broken I decided to run though the main sensors.
As I got to the cam sensor I noticed there was oil on the top of the plug. I proceeded to unplug the connector and the plug on the cam sensor was FILLED with oil.
I ordered a new sensor and cleaned up the plug. Hopefully that was my problem. I will update this once I am able to test the new sensor.

Has anyone ever heard of this happening? It certainly seems like this might be my culprit

Pretty common with those sensors.
 

hvyman

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I would replace the capacitors anyways. There like 10$ and take maybe a hours time.

Also could be map sensor.
 

Supra mn

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I would replace the capacitors anyways.
Not a bad idea, but open the ECU up and inspect every solder joint (not just the capacitors) with a magnifying glass. Look for gaps in solder joints, cold solders (globs of solder that didn't heat the board up enough to make a good connection), loose pins, etc. and re-solder them.
I don't think your ECU is the culprit in this situation, but it's a good thing to do either way.

Did you do the boost leak test while the car was warmed up and misfiring?
If you try to start the car again after it's been running for a while, does it crank for a long time before firing up? Could be excessively hot fuel in the rail. (I suspect I have this issue)
Maybe try putting a screwdriver to each injector and listen to see if they're all cycling while it misfires.
Just some ideas. Usually it ends up being something simpler than you expected.
 

Backwoodsballer

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Well i swapped out both Cam Sensors and was able to drive the car over the weekend with no issues. Hopefully this was the fix i was looking for, I am just going to keep an eye on those plugs to make sure they dont fill up with Oil again
 

suprahero

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If you aren't running high boost, I'd regap the plugs back to .025. Hopefully the cam sensor fixed the problem. I was thinking it was definitely in your coolant temp sensor. Good luck.