Forum Index
Jeep Horizons HomeLinksJeep Horizons Tech Write-upsJeep newsLand useContact

 Watched TopicsWatched Topics   FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Rough Idle on my Cherokee


 
Post new topic   Reply to topic     Forum Index -> Cherokee Forum
View previous topic :: View next topic  
Author Message
ua50
Member


Joined: 20 Jul 2005

PostPosted: Wed Jul 20, 2005 8:36 pm    Post subject: Rough Idle on my Cherokee Reply with quote

I have a 2001 Cherokee Sport 4x4. I have recently began to have some hard starts after the vehicle has been sitting for awhile. The engine cranks but is not firing up right away. This only happens on the first start up after it has been sitting all day or night. I am now noticing that the engine is idling rough when in park or at a stop. I noticed that intermittent bursts of air were coming out of the tailpipe (no smoke) as the vehicle idled. I just recently changed my spark plugs, changed oil, and installed a new battery. Anyone have any ideas? Could it be a fuel pump or clogged fuel filter? Any ideas or suggestions would be appreciated. Thanks.
_________________
2001 Jeep XJ 4x4
Back to top
View user's profile Send private message
ThePhantum
Pissed-Off Admin
Pissed-Off Admin


Joined: 23 Jan 2004
Location: I knew it...I'm surrounded by Assholes!

PostPosted: Wed Jul 20, 2005 9:41 pm    Post subject: Reply with quote

So it ran fine before the tune up and bad aftewards?

Things don't normally do that just by changing plugs. Did you lean on anything while you were changing them? It's possible a vacuum line was kinked or knocked loose someplace.

Is it throwing any codes?
_________________

97 XJ Sport with a bunch of stuff
Quote:
Never argue with idiots, they drag you down to their level and beat you with experience
Back to top
View user's profile Send private message AIM Address Yahoo Messenger MSN Messenger
ua50
Member


Joined: 20 Jul 2005

PostPosted: Thu Jul 21, 2005 6:39 am    Post subject: Reply with quote

Thanks for the reply. I went out and checked all my lines and hoses and everything looks ok, the Jeep is not throwing out any codes. I have had this Jeep for a year now and it always had a little bit of a rough idle but it just seems more apparent now, especially with the choppy bursts of air coming out of the tailpipe. I guess that is where I am hearing it the most, in the exhaust pipe, I had the hood open this morining, the Jeep fired right up, and I did not notice any abnormal vibration, jerking, stalling, etc. as I looked at the engine, but I could hear the occassional choppy burst of air coming from the exhaust pipe. Any other ideas or suggestions?
_________________
2001 Jeep XJ 4x4
Back to top
View user's profile Send private message
ThePhantum
Pissed-Off Admin
Pissed-Off Admin


Joined: 23 Jan 2004
Location: I knew it...I'm surrounded by Assholes!

PostPosted: Thu Jul 21, 2005 8:09 am    Post subject: Reply with quote

How many miles are on it? This is a shot in the dark but it could be something like a bad/clogged cat.
_________________

97 XJ Sport with a bunch of stuff
Quote:
Never argue with idiots, they drag you down to their level and beat you with experience
Back to top
View user's profile Send private message AIM Address Yahoo Messenger MSN Messenger
ua50
Member


Joined: 20 Jul 2005

PostPosted: Thu Jul 21, 2005 8:38 am    Post subject: Reply with quote

It has 63,000 miles on it. It had 54,000 miles on it when I purchased it. When I changed the plugs last week, they appeared to be the originals, Champion RC12ECC. They were pretty corroded, and burnt looking. I replaced them with BOSH Platinum plugs. I also replaced the original battery with a Duralast battery I picked up at Autozone. This was my first time replacing plugs, I followed the directions from this web site in the "tech" area. I noticed the harder cranking prior to the change in plugs/battery but not the rougher idling. Other than a kinked hose or wiring, any reason these new plugs or battery may be causing a rougher idle?
_________________
2001 Jeep XJ 4x4
Back to top
View user's profile Send private message
Drake69
Member


Joined: 26 Mar 2004
Location: Stormtroopin....

PostPosted: Thu Jul 21, 2005 1:25 pm    Post subject: Reply with quote

When replacing plugs, you have to expect a rough idle for a short while. The computer has to catch up to the new plugs some, but I would've thought a week would have been long enough. Is this a daily driver or an occasional one?

Just an FYI, I run Borsh Platinums in mine, and after three days it was purring like a kitten. Also, what gap did you set yours at? They're supposed to be gapped at .036. The battery shouldn't be the problem though.
_________________

Back to top
View user's profile Send private message
ua50
Member


Joined: 20 Jul 2005

PostPosted: Thu Jul 21, 2005 5:41 pm    Post subject: Reply with quote

I actually just changed the plugs on Monday 7-18-05, so it only has been few days, yes this is a daily driven vehicle. The guy at the parts store told be to gap the Bosch platinums at .035 which I did, would changing to .036 make a difference? I will see how she idles tonight, I had never heard of the computer having to catch up, thanks for the info.
_________________
2001 Jeep XJ 4x4
Back to top
View user's profile Send private message
ThePhantum
Pissed-Off Admin
Pissed-Off Admin


Joined: 23 Jan 2004
Location: I knew it...I'm surrounded by Assholes!

PostPosted: Thu Jul 21, 2005 9:52 pm    Post subject: Reply with quote

As far as the gap, 0.035 is the spec...so I don't think the gap is the problem. If the rough idle comes back, try disconnecting the battery (both terminals) for an hour or so and see what it does then.

I've never heard of the computer catching up either. I've replaced my plugs, wires, etc. at least 6 times since I bought the Jeep in 97...I've never had the ECU play "catch up".

When you disconnect the battery for a half hour or so it resets the ECU (you can also do this with a DRB scan tool as well). The ECU then "learns" the engines sensor input signal ranges over the next 300 miles or so. This will not cause hard starts or rough idle. If you install new plugs the same thing is true...it might not run it's best, but it certainly will not be a problem child.
_________________

97 XJ Sport with a bunch of stuff
Quote:
Never argue with idiots, they drag you down to their level and beat you with experience
Back to top
View user's profile Send private message AIM Address Yahoo Messenger MSN Messenger
Drake69
Member


Joined: 26 Mar 2004
Location: Stormtroopin....

PostPosted: Fri Jul 22, 2005 1:29 am    Post subject: Reply with quote

Weird. I double-checked my instructions the guy at Autozone gave me, and I have written down .036. Very strange.

Also, he's the one that told me about the ECU "catch-up", but I also have a performance chip in mine as well. Ohh well.
_________________

Back to top
View user's profile Send private message
ua50
Member


Joined: 20 Jul 2005

PostPosted: Sat Jul 23, 2005 9:05 am    Post subject: Reply with quote

I swapped out those BOSCH Platinum spark plugs and replaced them with Champion Platinum Power plugs (RC12PEC5) and the Jeep is purring like a kitten. I was researching on some other online sites and starting reading where other people had problems with the BOSCH platinum plugs in their vehicles (not specifically Jeeps) so I thought I would try a different brand of plug and it seems to have done the trick. No more rough idle and no more sputtering out of the tailpipe. I am not saying that the BOSCH plugs are not good plugs, but my Cherokee seems to agree with the switch.
_________________
2001 Jeep XJ 4x4
Back to top
View user's profile Send private message
Drake69
Member


Joined: 26 Mar 2004
Location: Stormtroopin....

PostPosted: Sat Jul 23, 2005 10:05 am    Post subject: Reply with quote

Not the point. It's whatever works PROPERLY in your Jeep that matters.

Glad it's nice and smooth again. thumbs
_________________

Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic     Forum Index -> Cherokee Forum All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Visit links4jeeps.com for write-ups, forums and clubs




Jeep®, Wrangler, Cherokee, Liberty and Grand Cherokee are copyrighted and trademarked to Chrysler LLC.
jeephorizons.com is not in any way associated with or endorsed by the Chrysler LLC.
All other content is copyright Jeep Horizons 2004-2008.
Tech write-ups Links Discussion board Land use News Site Map Terms of Use

Powered by phpBB © 2001, 2005 phpBB Group