Rough Idle?

[Saurian]

I'm following up on a couple of posts here... I read in this forum about pulling the codes from a digital odo, got a 2.5... In the Wrangler forum, I read that this is a problem with the idle air control motor... I followed the advice there, pulled the throttle body, and cleaned it all up. Started it without the map sensor, so it threw a check engine light... I went to AutoZone, they scanned it, and found only the map sensor code, the IAC motor is working perfectly...

So, my Jeep, 2000 XJ is idling a bit rough. Not really bad, but fluttering about 30-50 ish up or down when at an idle, warmed up or cold start. Just one of those things that I wonder what it could be, seeing as how my friend's '95 seems to run smooth as anything... It's had all it's oil changes, air filter's in good shape, throttle body is clean, as is the IAC motor and housing now. Any ideas on what could be causing this flutter?

 

[dingus]

antennae help needed

when i screwed up my map sensor vacuum tube, my jeep ran really really rich... perhaps yours is similar and fouled the plugs...?

...or is it the 2000 xj's that don't have spark plugs...?

 

[Saurian]

The vac line appears to be fine, at any rate, it only threw the light and error when it was unplugged... It has no distributor, but has brand new plugs... Maybe the fuel injectors are gunky? I just passed 60200 miles on it the other day...

 

[Saurian]

Just popping this post back to the top in case anyone has any insight... Jeep runs great, and the idle is not too bad, but the tach moves gently about 1/8 inch from normal every now and again when stopped... Plugs are great, throttle body is clean, all should be well... Any suggestions.

Oh, nad regarding another of my posts, there is still a tapping sound, and I am not too sure that it is a crack in the exhaust manifold, but it may be... If you are looking sparkplugside to the engine, it is below the plugs around the 3rd cylinder from the front, like someone is tapping the block with a pen. There is, however, no loss of power or anything like that, Jeep can still beat most things off the line, and climb hills as it needs to. Any thoughts/suggestions are always more than welcome.

 

[XJNick]

and the idle is not too bad, but the tach moves gently about 1/8 inch from normal every now and again when stopped...

Mine used to always do this. Especially noticable when the A/C was on. After worrying about it for a while, I decided it must be normal :wink:

-Nick :!:

 

[jay79cj7]

My 2000 XJ is doing something similar as well... The other day I had a tapping coming from the back of the engine when cold. It went away when warm, but now tonight, I heard a softer tapping that sounded like it was under the valve cover. I have noticed that the tach bounces just a little bit lately when idling. Not really enough to even notice, but the needle moves a little bit, which is not normal for it. I just passed 73k.

 

[hatemaker22]

one thing that the 2000 xjs are famous for is the 4x4 shifter handle loosening up and making a rattling noise that sound like it is coming from the transmission, alose the exhaust rattles in the rear of the vehicle. if you get the transmission rattle noise, just barely pull up on the shifter and it will go away.

 

[Saurian]

I heard about that one, and it indeed does happen... Anyone know of a way to tighten it? Re: the idle problem, it's when it is in drive too; I'll come to a stop, and the tach'll be weaving up and down ever so slightly, but enough to make me wonder, as it sat still as death when I first got it, 2 years and 40,000 miles ago...

 

[MudderChuck]

Not to familiar with the newer models, but in the older models when it hunts a idle, it´s usually a vacume leak. Could be a very small leak, and nothing much to worry about, as the ECU will compensate and adjust the fuel mix.
I´ve had an occasional load of gas tank injector cleaner, help with the idle somewhat. Unually appeared as something resembling a miss, not RPM changes.