Hi guys, tried searching and found few almost similar threads but no answers. Well the case is my engine overheated about a month back. So got a new rebuild engine and had it installed. However the problem is now that after running a while and after the temp reach bout 85-93C the engine becomes rough and sluggish at low rpm (below 3000 or so, idle maintains at 1000rpm but engine sounds like a motorboat and vibrates) but once it reach higher rpm and boost comes in, all looks good. If I leave the car at idle for a few min it starts getting better as the temp reduces. Compression was tested and looks good on both rotors. Tried changing the coils and cables but results was the same. Than I removed the front injector plug (leaving the back) and the car died. So I tried doing the opposite and the car still moves at a lower idle. (This is only when the car is hot, when the engine is colder either injector can be pulled out without the engine dying). So thought might have some problems with the injector. So put in a set of new injectors and the problem is still there. Running out of ideas and hope someone can help out with this. Thanks

 

Do you have stand alone engine management? My car is behaving similar to that(E6K), in my case, the car runs very rough at about 2000-3500 rpm, someone suggested an ignition problem, but I have not been able to find an issue. Mine smooths out at 4000 and up as well. the rough running seems to be mainly under no load. I'll be aqsking the question on the Haltech forum. Carl

 

I got the same symptoms using both the standard ecu and microtech LTX-12 didnt have this problem before the new motor though.

 

Any out there that can help? Coils, cable, spark pulg, injectors all has been change but problem still persists when it get hot (85C) or so. Microtech has been properly tune (The problem was there also with the stock ecu). Fuel pressure and compression all looks good.

Why is one of the injectors not injecting enough fuel when the temperature rises?