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03 3.8L dies on idle, sounds like miss, drives great?

567 views 1 reply 1 participant last post by  Dark 
#1 ·
Ok, my girlfriend blew up her 3.8L in her 04 V6 with a 5 speed manual, she ran it with no oil change and no oil... I did a motor swap with an engine from an 03 that was wrecked. I used mostly all the donor engines parts with the exception of: wiring harness, R side header and associated emissions crap, AC compresser, coils. I installed new plugs and wires.

I got everything installed and the engine crunk right up and ran. Origionally I had tried to reuse the plug wires and apparently some were bad because I was getting arcing between the plug wires on the coils and the wiring harness plug on the coils. I imediatly shut off the car and swaped the coils with the ones from her origional engine and had the same issue so I installed new plug wires and fixed that issue.

Now comes to my main problem: the car runs fine going down the road, I notice no hesiation or anything but when I stop and it has to idle it will often stall out. I listen to it and the engine sounds like it is missing. I've read about vacuum leaks wreaking havok on these engines.I can hear a sharp whistling sound that sounds like a vacuum leak coming from the passenger side near the fire wall but when I spray every vacuum line I can see down with carb cleaner I hear no differnce in idle. I also can hear the sound of an exhaust leak when I'm driving it. Possibly I don't have the pipes mated to the headers correctly? Her car was running fine prior to this. I was told the donor car ran fine and was wrecked in the rear end, but you know how that goes.

I swapped the IAC with the one from her engine(which crank up and drove on to the trailer and back off to get in my shop just fine before we did the swap, except for the knocking of course). Problem still persists.

I know it has to be something simple but what could it be? It has new plugs with correct 0.054 gap, new plug wires, coil pack comes from her motor, IAC came from her motor. Throttle body is from the donor.

What could be causing this miss and stall at idle but have the car drive just fine down the road?
 
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