engine stutter/misfire at 2.5k RPM

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guth_64

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My wife's 2004 liberty sport has 170k. After changing all 6 coils, I am getting some weird engine malfunctions.

Codes are P0204(#4 fuel injector) and P0304(intermittent code. #4 misfire)

resistant on the fuel injector is good and the issue exists in the same location after switching coils.

The issue started shortly after changing the coils. Wife would be driving along and all the sudden she couldn't get over 50 mph. Car would not accelerate past that. Lately, once the rpm'***** 2.5k, the jeep bucks like a bronco until you back off the gas. This is consistent as the first failure was intermittent.

any clue whats going on???

Cleaned throttle body and IAC. No change.
 

renegade 04

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It sounds like a clogged injector. I would try some fuel injector cleaner. Also check the spark plugs and see if they need to be replaced or re gaped.
 

guth_64

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spark plugs were swapped and issue still exists. Tried fuel injector cleaner to no avail.
 

teeje

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I had the same issue. O ring failed on the injector and the injector got all kattywampus. Replaced the injector no issues since.


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JasonJ

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Stop swapping coils for an injector DTC. Swap injector instead. Clear faults, re-test drive. If the DTC's come back of the same type, but for the cylinder where you moved the suspect injector, there ya go.

I agree with renegade.. since the injector checks out electronically, it's likely that it is physically stuck in some manner. Since you said this started after changing the coils, perhaps it is possible that you damaged the injector wiring or connector on inj #4 as well.
 

guth_64

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replaced the suspect fuel injector and all o-rings. it was a ***** getting those out. Problem still exist :( any other suggestions?
 

Billwill

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First check the wiring to the injector before replacing the PCM. If there is an injector wire fraying to chassis then it will blow the new PCM as well!

Try disconnect battery and re-plug connectors on PCM a few times in case there is a bad connection at the PCM.
 

guth_64

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Took it to an indy shop and everything checked out ok. Anyone know a reputable place to buy a pcm?
 

guth_64

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Replaced PCM and problem still exists. Jeep runs fine until you hit 2.5k RPM. This is super frustrating. Any sensors anyone can think of??
 

teeje

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Replaced PCM and problem still exists. Jeep runs fine until you hit 2.5k RPM. This is super frustrating. Any sensors anyone can think of??



Are you getting good fuel pressure?


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Logan Savage

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Does a noid light flash when hooked to the wires for that injector ? I'm not sure I trust your shops diagnosis when they say everything is ok . Obviously you still have the problem & probably the injector code .
I bought a plug & play pcm off ebay & weird though it was , the same injector driver in the pcm was bad as the one I replaced . I returned the pcm & they sent me another one & everything has been fine since .
If you're still getting that same injector code & you've replaced that injector , make sure a noid light flashes when connected to that injectors wires .

My problem was also with # 4 injector code . Maybe you bought the pcm I sent back .
 
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guth_64

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Update. The jeep started misfiring and we took it to another mechanic while on vacation. They had it for 5 days and came back with the PCM again. I replaced the PCM and symptoms still exist. Wiring looks good. Fuel pressure ok.

When I replace the PCM the check engine light comes on immediately. The misfire disappeared until i drove approx 200 yds.

All this started happening after I replaced the coil packs. It would run fine and then occasionally it wouldn't go above 2.5k rpm. If you restarted the truck it would work just fine and the CEL would eventually go out. Then after I replaced the camshaft position sensor it started happening more frequently and now full time. thoughts????? tired of this mess
 

HoosierJeeper

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What brand camshaft position sensor did you use? The Jeeps only like mopar ones.
 

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