I have a realy weird running issue. Anyone know whats gone wrong.

[240sxRAOR]

First off we put a ka24de in a 89 body and have a few upgrades done such as exhaust, intake and flywheel. Everything was runing fine though it was timed by ear and later properly timed. The car is definetly misfiring and in my opinion I think its a spark issue. The weird part is it started to misfire after 6000 rpm and I though it was the limiter but then it started doing this heavy misfire at 5000 and later during the trip 4000. I took it home and checked ignition timing and it was dead on so I thought mabye the new headers are giving off too much heat and the spark wires increased resistance. I let it cool off overnight and the next day I tried to drive it started misfiring badly around 3500 and then 3000 finaly 2000 its barley driveable now. Anyone have any idea, I'm going to try resetting the ecu to see if its the culprit. I tried to find the problem on here but had no luck.

[tom@ica]

Is it throwing codes? Check injector connectors/wires and plugs

[240sxRAOR]

89' 240sx throw codes (that'll be the day). We have new wires and plugs. Its to consistant to be a loose conection and it was running great for 100 miles after we put the engine in. I have a fealing its something computerized and I belive it has alot to do with engine load. It got consitantly worse over 2 days. Its a heavy misfiring too, like worse than runing on 2 cylinders which the old motor did when the injectors went bad. I'm actualy a mechanic and given enough time I'll probably figure it out but I'm just hoping someone has had the same problem and has a solution. Atleast its not an intermitant problem.

[240sxRAOR]

I guess it is a unique problem since I got only one response. I will update this post as I continue to diagnose the problem trouble is I hardly get time to work on my car. Any ideas on what could cause consistant heavy missfiring under load would be realy appreciated.

[LayNLow240]

Check your MAF sensor, make sure its plugged in and no frayed/cut wires going to it. If that checks out, go get a friends kade MAF and swap and see if problem persists.Thats what i would do first anyway.

[240sxRAOR]

I unplgged the maf to see the difference, its a good test to find something thats not working at all and there was a big difference so I have a feeling the maf isn't the culprit though I will do further testing. The tps didn't seem to do anything when I unplugged it so I think I could have a bad tps. Also I did find that my o2 sensor came disconected but 240sx don't realy care about o2 sensors other than less gas milege. Saturday I will have time to do some real testing so hopefully I find it and its a cheap fix.