1jz Running Rough

[MacDaddy_J_420]

So here is the deal, I have a good friend with a 1jz swapped 87 supra. Nothing specail just a stock 1jz swap bought from Jarco a while back. Recently it has started to run rough and break up at times. The issue has progressively gotten worse over time. When it starts to act up the tach will start jumping around, it causes spark plugs to gas foul, and will back fire. The car has brand new coil packs and the caps in the ecu have been replaced by driftmotion recently. We are thinking it could be either the cam/crank sensor loosing signal at times, or possibly the ignitor. So supramania I am asking you all what your thoughts on issue are.

Thanks

 

[SupraMario]

Cheapest thing first. Check what you can check and replace what is cheapest.
Is the 2jz ignitor the same as the 1jz? If it is, and your close come use mine.

 

[scottiedawg66]

the comment about the tach is throwing me off the scent here. but i think you should try gapping the plugs (always use NGKs) (i believe .027 ish is about what I run) since it would be easy and free. I also recommend swapping your igniter and ecu into a known good running car. since its also easy and free. if those check out Id start trouble shooting sensors. good luck!

 

[MacDaddy_J_420]

SupraMario - I don't think the ignitors are interchangeable becuase the only US ignitor that will cross over to the 1jz I believe is one off of a 95 toyota avalon and a new one is around 500+. If it does though you will get a visit from me soon.
scottiedawg66 - Plugs were pregapped NGK's and were replaced when the coil packs were. Because of the tach bouncing we are believing that it is the crank position sensor loosing signal to the ecu momentarly, it is just a bitch to get to or it would already be replaced.

 

[MacDaddy_J_420]

Supramario - turns out I may be coming to try the ignitor on your car after all.

Any one else have any suggestions on what this could be. We are also considering that the map sensor has went bad, that could be the cause of the condition going from "sometimes" to "all the time". If the car backfired and went into the intake the map sensor would be right in its path.