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2006 WK 5.7 Hemi misfire in cylinder 6

248 Views 2 Replies 2 Participants Last post by  Shahabuddin
For the love of God, could someone please highlight to me the probable causes of a misfire;
Symptom Primary:
1) Shaking engine on cold start until warm.
2) Gas mileage has dropped some.
3) Cylinder 6 spark plug gets dirty.
4) Would misfire on highway speeds but after a shop opened the whole engine and they say they found nothing it stopped the highway misfire... They asked for a ECM change and changed it but didn't help!
I paid for the ECM + Programming and can't refund.
Would like to keep the vehicle but with the least cost incurred to the bank.
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13,334 Posts
misfire is BASIC automotive.

jeep is STOCK no aftermarket BS, programmers, chips, lower thermostats, miracle parts?
Any other codes ANY ?

Do you have a SCANNER - able to see live data? makes this a fast snapshot.
That will give us a fast big picture.

IF no then basic tests.
Fuel pressure PSI?
Spark plugs - firing - plug appearance, brand and #.
compression test.
 

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Discussion Starter · #3 ·
My absolute sincere apologies for the late reply, all the shop says is that there isn't pulsation from the ecu to the no. 6 fuel injector...
My question, is it true that a weak engine with lower than normal compression cause the ecu to inject more fuel?
The vehicle is factory stock.
OEM champion plugs not even 5k miles on them.
The cats is also showing signs of being burnt due to over fueling. It actually spits out unburnt fuel when warming up from full cold temperature.
Tire Grille Wheel Hood Automotive tire

Warm at operating temp compression test is 140 PSI which I think is a bit low but I could be wrong.
As of my last check at the shop the ignition was on spot for all cylinders and that's all that I could look through because I don't have a scan tool of my own...
misfire is BASIC automotive.

jeep is STOCK no aftermarket BS, programmers, chips, lower thermostats, miracle parts?
Any other codes ANY ?

Do you have a SCANNER - able to see live data? makes this a fast snapshot.
That will give us a fast big picture.

IF no then basic tests.
Fuel pressure PSI?
Spark plugs - firing - plug appearance, brand and #.
compression test.
 
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