Rough idle

[first&lastKJ]

Our 02 had developed a rough idle. I bought the OEM NGK plugs, new PCV valve (still had original). After I installed the plugs and PCV valve, I cleaned the throttle body. When I started it up the RPM's were up, so I let it idle for a while then took it for a drive and the check engine light come on. I drove to Autozone, by now the RPM's were normal and idle was smoother. I went ahead and had them check the KJ and they said it was a code for the throttle position sensor, but they couldn't reset it.
After I drove it some more, the check engine light went out on it's own, Thank goodness!

 

[first&lastKJ]

After driving it for a few weeks the jeep still seems to have a bit of a rough idle. Anybody got any ideas, I dont know what to try next.

 

[Luke]

Did you clean your IAC when you did your throttle body?

 

[first&lastKJ]

Did you clean your IAC when you did your throttle body?

Yes.

 

[Dave]

Maybe the IAC got too much cleaner on it? Sometimes the IAC doesn't like that. Sounds like that might be it if there was not a rough idle before it was cleaned.

Maybe try a bottle of "Techron Injector Cleaner" or the "Techron Fuel System Cleaner" in the gas tank? Might not be it but wouldn't hurt anything.

Dave

 

[first&lastKJ]

Maybe the IAC got too much cleaner on it? Sometimes the IAC doesn't like that. Sounds like that might be it if there was not a rough idle before it was cleaned.

Maybe try a bottle of "Techron Injector Cleaner" or the "Techron Fuel System Cleaner" in the gas tank? Might not be it but wouldn't hurt anything.

Dave

I'll try that next fill up.
I've never had to use any type of cleaners like these before. I know people that have and they have had mixed results.

 

[rockymountain]

The only time mine is ever smooth at idle is when I first change the plugs. Mine has always had a slight quiver to it. I think it is normal for this engine. Any more than a slight quiver though could be any of the things you are addressing. I'd clean also the IAT sensor as well.

.. you may try to reset the computer by disconnecting the battery so it can re-learn with the new plugs and clean IAC and so on.

 

[Luke]

If you've have never had it done ... I would skip the additives and spring for the fuel injector cleaning at the dealership.

 

[first&lastKJ]

It is more of a "slight quiver".
How much is a fuel injector cleaning at a dealer, and how do they do it?

 

[Luke]

I think I paid around a hundred bucks or so ... (CDN.) Someone can give you a more technical answer than I can but they hook a machine up to the the fuel rail and clean it thoroughly.

According to my invoice : 1 hr labour + VU01535 Fuel Syst $18 (solvent?)

"Mopar Fuel Injection Service" Service directly flushes the injectors via fuel rail port. Cleans deposits from fuel injectors, frees sticking piston rings and helps remove deposits from intake valves.

 

[sevenhelmet]

You don't need a dealer for the fuel system cleaning, any decent full-service auto shop can do it. Some charge more, some less.

I use Seafoam fairly regularly in my gas and brake booster line and I don't have any idle issues. I cleaned a bunch of carbon out of the throttle body and IAC last week, but my idle has been smooth the whole time.

 

[first&lastKJ]

Thanks for the info. I may just take it to a shop and let them do it if its only a hundred bucks.