Intermittent engine running rough issue?

Tiny
OLDSCHOOLZJ
  • MEMBER
  • 1998 JEEP GRAND CHEROKEE
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 253,000 MILES
My vehicle listed above ZJ has recently started running rough at times like a miss or trash in a fuel line. When I first start it, it idles a little rough then clears up but comes back sporadically. When it's rough it has a hesitation and the occasional miss but when it's smooth it's great no problem no hesitation nothing just smooth as silk. I pulled plugs and just normal wear. Same with distributor cap and rotor button. I cleaned everything, no change. I ordered fuel pump but was sent the wrong one, so I replaced the fuel filter on old pump and put it back in. Now it's running really good with the exception of the sporadic hiccup. Starts good idles good most of the time but still runs a little rough at times. I don't know what to do next. Can't afford a mechanic. I removed and cleaned the idle control module which helped a little. Any suggestions? My check engine came on but came back no data then went out and is still out.
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Wednesday, October 5th, 2022 AT 12:01 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,014 POSTS
Hi,

Oftentimes, a rough idle is the result of an engine vacuum leak. If you haven't already, I recommend checking for a possible leak.

Here is a link that explains how to do it:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, it's odd that you weren't able to retrieve diagnostic trouble codes when the check engine light was staying on. Let me know if that happens again.

Let me know what you find.

Joe
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Wednesday, October 5th, 2022 AT 8:14 PM

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