Misfire
10-10-2014, 09:48 PM
#1
Junior Member
Thread Starter
Misfire
Idles a little rough but when I get on it it smooths out runs great and has plenty of power but out of nowhere it will start to run rough buck and all and ill get a po300 po 302 and 303. Any suggestions as to where I should start looking into this?
Thanks
Thanks
Last edited by scatgo; 10-11-2014 at 05:53 AM.
10-11-2014, 07:58 PM
#5
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Join Date: Nov 2010
Location: In the middle of Minnesota!
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Year: 1999
Model: Cherokee
Engine: 4.0
When you see a "random misfire" (P0300) with other single cylinder misfires, the problem is usually one thing. In this case, gotta look for a common cause.
First thing that a technician would do if you brought it into a shop would be to verify fuel pressure. Must be done with a fuel pressure gauge, which you can rent very inexpensively from many parts stores, call around for availability.
For a 98, you need to have 49 psi at idle, plus or minus 5 psi.
Yes, there are other possibilities, but you need to verify fuel pressure first.
Good luck and keep us updated!
First thing that a technician would do if you brought it into a shop would be to verify fuel pressure. Must be done with a fuel pressure gauge, which you can rent very inexpensively from many parts stores, call around for availability.
For a 98, you need to have 49 psi at idle, plus or minus 5 psi.
Yes, there are other possibilities, but you need to verify fuel pressure first.
Good luck and keep us updated!
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