My 2005 Neon SXT has ~135K and is misfiring, particularly above idle rpms. This is evidenced by popping sounds, power loss, and fuel from the tailpipe... but no codes. Recently changed coil pack, spark plug wires, plugs, air filter. Also had timing belt/water pump replaced.

I also had a recurring problem (now partially fixed, see below) with the car not idling when it is really wet/humid outside, However once the engine got up to temp, it ususally ran fine at idle. I sprayed all the sensors with a water bottle to check connections, but no luck. We then replaced the coil pack and spark plug wires. Still nothing changed. Then I had my mechanic replace the timing belt, water pump, idler pulley and do a coolant flush.

Since the TB change, I started experiencing minor misfires, usually during the same time I was having idle issues (ie wet/humid). The mechanic suggested I clean the throttle body to remove gunk form the throttle plate...and thar she idles!! But now I have worse misfires than before, all up the rpm range .

I took the throttle body apart again and checked my electrical connections, IAC gasket, hoses. Perhaps I damaged the throttle position sensor/IAC when I took them off? I removed the sensors prior to cleaning the throttle body with throttle body cleaner, which cleared up the definite "stick" in the throttle I had and resolved the idle problem.

Right now I am left with a badly misfiring engine without any codes. The fuel injectors all had a resistance of 13.4-13.6 ohm (spec is 12ohm), but I have not messed with the fiuel injectors otherwise.

Any thought are appreciated!

 

have you reset the pcm yet?

 

TejasMtnBiker, I have reset the pcm by disconnecting the Neg terminal for several minutes, unless there is another trick.
I have ordered a used stock throttle body with sensors from a parts car, should arrive in a few days. I am not driving it right now with the misfiring.

 

Update:
I picked up a stock throttle body with IAC and TPS intact from a junked 2005 (I think I may have damaged the original TPS or IAC when I took them off earlier). The used throttle body required a little cleaning, but after install and driving around tonight, the misfires have reduced and seemed to stop after a while. I will drive it to work tomorrow to see if it stays misfire-free.

As for the stalling-when-wet outside, I will update the next time it rains.

This whole time I have not seen any codes. Here's hoping for the best.

 

the only way I reset any pcm on dodge is pulling the pcm fuse or fuel pump fuse

 

I'd stick to disconnecting the battery and turning the headlight switch on (makes sure the system is completely drained) for a PCM reset. Pulling the fuel pump fuse doesn't perform a complete reset.

 

lol all these years! ty dt ^^