I have a 2005 Chrysler Town & Country with a 3.3L engine. My problem is low speed misfire.
This van had a coolant leak that was not corrected in time for it to cause the engine to overheat and the heads to become damaged. It also had a bit of a misfire before this happened.
I replaced the radiator and heads with re-manufactured ones and the engine fired right up and it seems to be fixed except for the low speed misfire, which continues.
It misses at idle and say below 25 mph but seems to be okay once you get up above that.
So far I’ve replaced the spark plugs, spark plug wires, coil pack, EGR valve and the idle air control valve all without fixing this problem. There are no OBD codes showing up. The fuel pump pressure has been tested and it’s within specs.
I can attach the sound of the engine idling with the air filter & cover removed. There is an odd, intermittent sucking noise coming from the throttle body intake that coincides with the misfire, but that may be nothing.
While I've been waiting for your reply I removed the throttle body and cleaned it out. It was full of gunk but it's clean now, and the miss remains. Still waiting for a reply. I just changed the throttle position sensor with no luck. I've been trying to find a vacuum line off somewhere but can't see one.
Can you offer any suggestions as to what may be going on here or what I can try next because I'm just about out of ideas.