Multi cylinder misfire?

Tiny
WAYNE LARSON
  • MEMBER
  • 2003 JEEP GRAND CHEROKEE
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 72,000 MILES
After driving my vehicle listed above for an hour or more, will get multi cylinder misfire, (throws codes p0300, p0302, p0303, p0304, p0305) if I shut the engine off and let it coast in drive for a few seconds and turn it back on it runs fine again, it might do it again in 10 or 15 minutes, or it may not, have replaced the injectors and insulated them against heat soak, new spark plugs, all new filters, still does it.
Tuesday, April 1st, 2025 AT 3:21 PM

1 Reply

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,257 POSTS
Does the engine make unusual noises while running? Also, does the engine have the correct weight engine oil? If not, the lifters can get over pressured and hold the valves open. Also, there is a coil pack or crankshaft angle sensor that can overheat and cause this problem as well. I would try the ignition coil pack first, here is what I am talking about for clarification. Clear the codes once completed. Check out the images (below). Let us know how it goes.
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Wednesday, April 2nd, 2025 AT 12:00 PM

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