I've been having an issue with my truck with the idle. I changed the MAP, PCV valve and IAC a while back and it has not been right since. I've put a few hundred miles on it, changed injectors, plugs, coil packs, throttle body gasket, lifters and followers and cleaned the throttle body. It still does not idle right. It's a little rough, bogs down occasionally and is just not right. I'll be fogging the intake and vac system this weekend to check for leaks and see if I can read the intake temp sensor data with my scan tool but after that I'm out of ideas. Is there anyone out there that can read a data log for this thing? Maybe give me an idea where to look? I'm basically out of ideas at this point and don't want to drop it off at a dealer or another garage that's going to hit me for 400 bucks and tell me they reset the idle re learn. I do not have a CEL on and I have no codes to go off of either.

2003 4.7 4X4

 

Does it idle rough as soon as it starts? Or does it take a minute or two, then start idling rough?

 

It's rougher when it's cold. It smooths out a little after it warms up but not by much.

 

Might try running some fuel injector cleaner thru it..... but, that won't have immediate results.....

 

Fuel injectors are brand new. I also run a can of seafoam through the fuel system about every 6 months. For the last few months because my drive to work is so short now I also only run 93 or 94 fuel. I make sure I let it warm up for abut 10 minutes before I leave and i'll hit 4 to 5k rpm at least once on the highway just to keep it from building up carbon deposits.

 

It may be possible one or both of the sensors, MAP, or IAC may be defective since your problems started after you replaced those parts?

I had a lazy MAP/Throttle position sensors where it causes random idle issues and at times speed surges when on highway. spent months looking for problem, no codes, no nothing, replaced the throttle position sensor anyways since users reporting that sensor is the cause of the surging. I replaced my MAP sensor and now the random idling and surge issues are gone.

Do you still have the original sensors? maybe put them back on and see if the idle issues go away?

I had no luck with PCV valves either, all the aftermarket ones make clattering noises. Went back to Mopar and bought the factory PCV and no more clattering noises.

 

I don't have the old parts anymore. I might order an OEM MAP, IAC and TPS though.

I don't have an issue with the PCV making noise. I must have gotten lucky.

 

Yeah, I would suspect map, first. IAC just controls idle speed. PCV is just a controlled vacuum leak....

 

I got my parts from Napaonline or O'reilly's if factory Mopar does not have them anymore for my TPS and MAP.

 

If you can't get mopar, go with standard motor products sensors..... they seem to have at least a reasonable rep. The cardone, dorman, and other 'low cost' manufacturers aren't with a hill of beans.