shanestyle

Hi all,

I've seen a few threads about this, but I'm pretty inexperienced, and wanted to get advice about where to start.

I get a pretty serious rumbling from the back of the jeep while idling. The idling itself is pretty rough. When I grab the exhaust, the noise inside the car goes away (you can't really hear anything from the outside, it isn't rattling against anything)

So, I've read to check for vacuum leaks, iac, try fuel cleaner...
What should I start with? The idle seems to remain constant on the tach (between 500 and 1000), it is just the rumble and shaking that is a problem.

Thanks!

van island

Hi, you did not state the year of your jeep, but here goes( I'm a jeep tech)
your rumbling is most likely a loose cat' element (lifetime cat replacement warranty )
intake gasket leak causing false o2 readings -repair
craked exhuast header causing false o2 readings- weld up or replace
egr pinlte leak causing engine stall, no start,or surging on hiway- replace or block off
crank sensor degrading causing engine stall - replace
bad tps causing hesitation, bucking -replace
coked up thottle body and iac causing low idle speed no rpm flare when first started and stalling- clean throttle ang iac-do injector purge
this is a starting point, hope this helps, off course start with tune up
Eric

shanestyle

It's an 01, sorry about that.

I'm not getting a low idle, and no stalls or backfires. That eliminates some of the potential problems. I'll look into the other ones, thanks for the help.

shanestyle

Also, is there a way to check if I'm getting false O2 readings? Don't know anything about that...

Diesel

Hook up a scanner.

jeepcherokee89

jeeps have a lifetime cat replacement warranty??

Cherryokee

X2 - Lifetime Cat Warranty? Sign me up! Woo-Hoo!

UserID6095

The front o2 controls air/fuel mix. Easy way to test it, un plug it and drive it around. If the problem is worse, meaning it wants to stall and stumbles when you give it gas then the o2 should be good. If there is no change the o2 may be bad.

van island

there is a tsb re lifetime cat warranty, plus certain criteria has to be met.
re: how to test o2, have scanner hooked up,add propane to air intake and watch o2 # , then create vacuum leak and watch #.

jeepman156

Easy way to check if the cat is bad is to just get under it and shake around the cat or kick it. If you hear some metal hitting metal then you need a new cat. I had the same problem, cut out the cat.....problem solved

shanestyle

Quick Update:
For the first time, it didn't start this morning when I was leaving for work. Engine turned over but wouldn't start. It did start after the third try but was idling really rough.

I'm a little worried now bc of my holiday roadtripping. I might bring this in before I leave.

Could a bad IAC cause this?