2001 Jeep Cherokee poor gas milage - rough idle

JEEPER01

MEMBER
2001 JEEP CHEROKEE
6 CYL
4WD
AUTOMATIC
54,000 MILES

My 4.0 starts fine but after it warms up it idles so rough that the exhaust rattles, also gas milage has gone way down. Engine lt. Says cyl. 3 missfire. I have changed the spark rail. Plugs, and checked injectors. Replaced fuel pump. I have not changed O2 sensors. The drive rod for the oil pump and camshaft position sensor was recently replaced by a shop, so I assume the timing is ok. I took the cat. Converter out and it is ok.

3 Replies

OBXAUTOMEDIC

MECHANIC
3,711 POSTS

Hello,

Well, to make it easier and so we don't have to spend time searching for the problem the jeeper2001 has could you please post the problem you are having.

.

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

Saturday, March 7th, 2009 AT 9:28 AM

BUICKRODGUY88

MEMBER
8 POSTS

I used to have kinda the same problem it would idle really rough and hitch really bad going down the road had to change the TPS (throttle position Sensor) and the upstream oxygen sensor (the one up before your cat. Converter. Hope I was of some help here.

Was this

answer

helpful?

Yes

No

Thursday, March 12th, 2009 AT 12:01 AM

OBXAUTOMEDIC

MECHANIC
3,711 POSTS

Ok,

Check for good spark it should be Bluish/White. Check IAC (Idle Air Control Valve), check compression fuel pressure and fuel regulater.
Check for vacuum leaks.

.

Was this

answer

helpful?

Yes

No

+1

Saturday, March 14th, 2009 AT 9:49 AM