Almost a year ago I decided to pull the 2.4l four cylinder out of my 05 TJ to do a complete overhaul. Bored .40 over, all new parts in bottom end. Had the cylinder head redone at the same machine shop that bored the block. New valves, lifters, springs, etc. Also stuck a new set of Stage 1 cams in as well. Fired it up for the first time the other night and it was idling rough. Motor will smooth out and run nice if gas pedal is pressed. Checked for vacuum leaks, did the IAC clean method, new plugs, all wiring and grounds are good, coil pack and plugs are fairly new, put fresh gas in with sea foam(thought injector may be sticking), double triple quadruple checked timing before putting rest of engine together, no CEL. Went for a short drive and engine would also die when coming to a stop. Decided to put a few pieces of tape on the throttle stop(doesn’t look to be adjustable on throttle body) to raise rpm’s up to around 1000 and it will run smoother, and won’t die when coming to a stop. This is my first non-carb engine rebuild and was wondering if computer may need to be retuned to correct fuel/air mixture? or other things to check out? TIA
Rough Idle After Overhaul
- Thread starter Khoule
- Start date
The throttle blade is normally closed at idle, the idle air goes around the throttle blade through the IAC and is controlled by the PCM. There's no mechanical adjustment.
You may just have a bad or sticky IAC.
Other than that, all my experience is with the 4.0.
You may just have a bad or sticky IAC.
Other than that, all my experience is with the 4.0.
I may be wrong but if you bored the engine and installed all new internals, to me it sounds like an improper break in procedure.
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