ken72

Just wondering how everyone elses XJ idles. Mine feels a little jumpy. I have heard that is common with these 4.0's. I have a 2001 and at stop lights it feels a little jumpy and the idle rpms seem to bounce just a little. Just wanted to see how it compares or if it is normal.

EvilMaster

Seafoam.

cjjackson2400

Mine does the same thing got a tune up and replaced all fluids gaskets ect. And still does it I asked the tech at the Jeep Dealership and he said its normal so I think your good.

ken72

I have been thinking about that but I have heard good and bad things.

I read it seemed normal but I have never felt a vehicle idle like this before. I have never driven another XJ before so I have nothing to compare to.

EvilMaster

I had a rough/jumpy idle on mine. Seafoam cured it completely, I can't even hear my jeep's engine at idle anymore.

I put a third of a can directly into the throttle body (be careful with this, go slow)

Then I put the rest of the can into my gas tank.

That stuff is amazing, I was expecting to maybe notice a slight increase. But I was blown away. The Jeep has never run this smooth, I am now sold on the Seafoam product completely.

ken72

I am nervous to use it, but I will think about running some.

kemjeep

try using gumout with regaine in it maybe two times following the instructs. it helped mine course just bought in July so dont have full history on it

45shutr

Seafoam is a great product, I would run a can of that, and after you do, then go through and manualy clean your throtle body. Manualy cleaning your throtle body after running the Seafoam might not be completly necessary but I think it is a good idea just to make sure it is really clean. I used to run that stuff through all of my Chevys and always had great results.

ken72

I did remove the TB earlier this year, cleaned it up and replaced the IAC. Its an IAC I ordered off ebay so I dont know if it was a good quality one. Maybe I will buy another one from the parts store this time and replace it.

45shutr

If it was a new IAC that you bought, I would doubt that would be your problem. Usually when your IAC is bad or dirty you will know it. The car will idle like complete crap, and more times than not stall out at idle. Cleaning your throttle body and replacing the IAC says nothing for the inside of your motor. And if there is a substantial amount of carbon build up in there, then that could very well be causing the symptoms you are experiancing. Just do the Seafoam treatment, it is super simple and inexpensive. After you have done that, then you can be sure that the inside of the engine is clean. At that point you can be fairly sure that soot or carbon build up in the engine isn't causing your problem. But even after the Seafoam, if the car still isn't running to your standards, then you can start throwing parts at it if you want, but at this point if I were you, I would start with the easiest most cost effective solution which is the Seafoam, and then go up from there.

45shutr

By the way I almost forgot, attached is a link to a quick resistance test that you can do on IAC. Good Luck.

http://www.ehow.com/how_5560848_chec...rol-valve.html

CRoading

Seafoam also made my jeep quiet during idle... Best solution I've found...

dans01classic

Dont try to fix something that isnt broken. it will likely cause more problems. My has done this sinse I bought it but it throws no codes and doesn't really bother me at all. I know If I try to mess with it ill kick my self in the tail and end up worse then i started. Everybody that I trail ride with that has a 97 up XJ all does this.

Diesel

Start with whats probably wrong, IAC.

Seafoam isnt the cure for everything, "jumpy" idle, in most cases seafoam wont affect it.

ken72

Its not super jumpy, just a slight adjustment is what it feels like. When I am sitting idle it feels like the engine is correcting itself every few seconds. Watching the RPM needle it looks like it just drops a hair and bumps back up. I read that the computer will adjust the idle as it sees fit for any fluctuations and that is all it feels like but I would like it to be more consistant. Its not throwing any codes right now so I am not to worried about it but I want to head off any potential problems. I have heard anything from timing to O2 sensors but again there are no codes so it could just be doing its job but I am just a little more sensitve to the idle movement.

BTW... I replaced the IAC earlier this year.