Piston Misfire

toochez007 · 03-05-2006, 08:18 PM

I've got a misfiring piston. Has anyone had this problem? Had to decarbon, and clean the fuel injector. Second option would be to have a "valve grind" which would set me back $2k. Any insight would be appreciated. It's a 2001 with only 78k miles!

**coppertop71** · 03-05-2006, 08:26 PM

Might need to add more info, how long or when did this start. I'm confused that you say misfire but I'm thinking to clogged a injector it would need to be back firing, but I would recheck firing order if that checks out try doing a compression check or tune up.

toochez007 · 03-05-2006, 08:44 PM

At 50,949 miles, I brought her in because I had a few rough starts. The car never stalled, but would dip significantly in RPM. I would press on the accelerator, and the car would hesitate and then jump forward. The diagnostic read "has multi cylinder misfire." I chose the cheaper option of rotateing the exhaust valves and decarbon, chemical flush fuel injectors, clean throttle body, and clean valves. The problem is slowly reappearing, and the jeep dealership wants to charge be that $2k to "possibly" fix the problem.

**coppertop71** · 03-05-2006, 09:04 PM

Quote:

Originally Posted by toochez007

I would press on the accelerator, and the car would hesitate and then jump forward.

I'm clueless to the misfire but I was had this problem above and found a crack in the plastic vacuum line to the MAP sensor on the firewall. Replaced the line and hesitation went away. As far as the misfire wait for more post, someone will probably relate to your problem.

anony91xj · 03-05-2006, 09:08 PM

The diagnosis wouldn't have said something that vague. I'll assume the CEL was on, what code(s) were in it?

Also, what exactly does the dealer say the problem is and why are they giving you a $2k estimate? What exactly does "rotating the exhaust valves" mean?

greasefingers · 03-05-2006, 09:10 PM

What engine do you have!

greasefingers · 03-05-2006, 09:17 PM

Vacuum leak, ERG valve not working (for the v8), or coil-pack. You can pull the packs, one at a time, and see if the engine runs worse. If pulling one does not send the engine bonkers, then you have found your problem. Leak-down test may be in order.

anony91xj · 03-05-2006, 09:18 PM

Quote:

Originally Posted by greasefingers

Vacuum leak, ERG valve not working (for the v8), or coil-pack. You can pull the packs, one at a time, and see if the engine runs worse. If pulling one does not send the engine bonkers, then you have found your problem. Leak-down test may be in order.

1) The V8 wasn't an option in the Cherokee (XJ), only the Grand Cherokee (ZJ/WJ). I'd guess it's a 4.0 since it's a 2001.

2) The 4.0 has a coil rail, you can't pull individual packs.

**coppertop71** · 03-05-2006, 09:26 PM

Quote:

Originally Posted by anony91xj

1) The V8 wasn't an option in the Cherokee (XJ), only the Grand Cherokee (ZJ/WJ). I'd guess it's a 4.0 since it's a 2001.

2) The 4.0 has a coil rail, you can't pull individual packs.

Maybe Grease is on something, could he try to pull injector connectors or spark plug wires to see if there is a problem he can narrow down to the source.

cobra7 · 03-05-2006, 10:42 PM

Are saying you're getting a cylinder misfire? Have you checked your spark plugs?

I was getting a cylinder #5 misfire when I first got my 2000 with 63,000 miles on it a couple of months ago. It had a lumpy idle, too. Turned out it just needed a tune-up. Runs smooth and strong now - no more cylinder misfire codes.

XJ4oh · 03-05-2006, 10:47 PM

What in Gods name are they gonna try and charge you 2 grand to do!?!?! Im guessing you took it to a Jeep dealership... They will most likely rip you off any way they can. "Rotating the exhaust valves" is total BS. If one is messed up then it wont help to put it on a different cylinder. Same thing with the valve grind. This misfire is becoming more and more common on the 2000-2001's it seems. Did you have the recall work performed on it? It dealt with the manifold heat sheild, and it stated it could cause a misfire or rough running. Get that check out asap. And dont let them fool you into shelling out 2k for some work. You can have a brand new engine for that.

Edit: Just checked that recall, and its for a manifold sheild to prevent a possible fire from occuring due to built up debris. But, I do think the misfire issues fall under a technical service bulletin, which is not a full on recall but they know about the problem since theyve had it enough. Thats my understanding.

**coppertop71** · 03-05-2006, 11:05 PM

[quote=XJ4oh]This misfire is becoming more and more common on the 2000-2001's it seems. Did you have the recall work performed on it? It dealt with the manifold heat sheild, and it stated it could cause a misfire or rough running. /QUOTE]

Check at the Alldata.com site for Technical Bulletins or Recalls for your make and Model. For a fee you can pay for the full bulletin but I dont think it worth it, a friend of mine purchase this and it was like a riddle to read. You can at least see if there is a bulletin or recall number to bring to your dealers attention but I would find another dealer first.

http://www.alldata.com/recalls/index.html

cobra7 · 03-06-2006, 10:24 AM

If I recall, the TSB is in regard to a cylinder #3 misfire caused by a heat build up from the manifold. The fix is to install a heat shield near the #3 injector.

I agree that for $2000, you could get a whole new engine. Doesn't make sense.

mylt1 · 03-06-2006, 10:44 AM

a milticylinder missfire can be caused by a long list of things. take it to a normal shop for a second opinion. the stealership is trying to screw you.

XJ4oh · 03-06-2006, 11:09 AM

Quote:

Originally Posted by mylt1

take it to a normal shop for a second opinion. the stealership is trying to screw you.

I agree 110%

03-05-2006, 10:42 PM	#10
cobra7 Registered User Join Date: Dec 2005 Location: Southern Chester County, PA Posts: 335 Profile Gallery Classifieds My Jeeps	Are saying you're getting a cylinder misfire? Have you checked your spark plugs? I was getting a cylinder #5 misfire when I first got my 2000 with 63,000 miles on it a couple of months ago. It had a lumpy idle, too. Turned out it just needed a tune-up. Runs smooth and strong now - no more cylinder misfire codes. __________________ COBRA7 ------------------------------------------------------------------------ [SIZE="1"]2000 XJ Classic (Black on Camel) \| 4.0L I6 \| AW-4 \| NP231J \| Dana 30 \| Chrysler 8.25[/SIZE]

03-06-2006, 10:24 AM	#13
cobra7 Registered User Join Date: Dec 2005 Location: Southern Chester County, PA Posts: 335 Profile Gallery Classifieds My Jeeps	If I recall, the TSB is in regard to a cylinder #3 misfire caused by a heat build up from the manifold. The fix is to install a heat shield near the #3 injector. I agree that for $2000, you could get a whole new engine. Doesn't make sense. __________________ COBRA7 ------------------------------------------------------------------------ [SIZE="1"]2000 XJ Classic (Black on Camel) \| 4.0L I6 \| AW-4 \| NP231J \| Dana 30 \| Chrysler 8.25[/SIZE]

03-05-2006, 08:44 PM	#3
toochez007 Registered User Join Date: Aug 2004 Posts: 6 Profile Gallery Classifieds My Jeeps	At 50,949 miles, I brought her in because I had a few rough starts. The car never stalled, but would dip significantly in RPM. I would press on the accelerator, and the car would hesitate and then jump forward. The diagnostic read "has multi cylinder misfire." I chose the cheaper option of rotateing the exhaust valves and decarbon, chemical flush fuel injectors, clean throttle body, and clean valves. The problem is slowly reappearing, and the jeep dealership wants to charge be that $2k to "possibly" fix the problem.

03-05-2006, 09:08 PM	#5
anony91xj Registered User Join Date: Dec 2004 Location: North Jersey Posts: 2,742 Profile Gallery Classifieds My Jeeps	The diagnosis wouldn't have said something that vague. I'll assume the CEL was on, what code(s) were in it? Also, what exactly does the dealer say the problem is and why are they giving you a $2k estimate? What exactly does "rotating the exhaust valves" mean? __________________ 1997 VW Jetta - Daily Beater <---Totaled, seeking replacement DD 2004 GMC Envoy - Wife's Ride

03-06-2006, 10:44 AM	#14
mylt1 Registered User Join Date: Oct 2005 Location: Virginia Posts: 5,874 Profile Gallery Classifieds My Jeeps	a milticylinder missfire can be caused by a long list of things. take it to a normal shop for a second opinion. the stealership is trying to screw you.