Engine skipping

[Firefighterf18]

Good afternoon,
I'm in the need of some help. I got a 02 liberty with 3.7 that has a skip when it feels like it. On cylinder 2. Once it starts to skip you cycle the key and start it up ans skip it gone.
I have replace the pistons and rings. 150 psi on all cylinders
Replace heads
Coil packs
Injectors
Swap ecm
Change fuel filter
Change spark plugs
I'm at a lost here. I check for coolant getting into the cylinder
What else do yall think I need to check? Thanks

 

[tommudd]

what plugs?

 

[Firefighterf18]

Factory spark plugs

 

[Firefighterf18]

I even try a Delco plugs also

 

[tommudd]

Meaning you replaced them with NGK coppers ?
Or stock as in the ones it came with?
Delco do not run well at all in any Liberty

 

[Firefighterf18]

It was stock replacement.

 

[tommudd]

Well there goes that

 

[Firefighterf18]

Do you think I need to swap in a set of ngk cooper's?

 

[jeeptorino68]

Bad coil?
Move the coil from #2 to another position. See if the problem follows the coil

 

[Firefighterf18]

I've swap coil to cylinder across from. It

 

[Yosarian]

Recently changed over all of our vehicles to NGK Ruthenium plugs (better pattern than Iridium), which includes our Liberty, and everything runs better. That said, for a miss or skip diagnosis I usually start simple; check plug gaps. Even with the new high dollar plugs I found a few that were out of range (and who knew that people actually install new plugs without checking their gap, but apparently it's a thing). Actually read some reviews of my new plugs where knuckleheads were complaining that they weren't gapped perfectly for their vehicle right out of the box... I dunno, is it just me? But I digress.

Then there's vacuum leaks. Recently discovered a split hose connecting my PCV valve that was just barely at the end of the barb and hidden on the underside. Grab some Mass Airflow Sensor cleaner and an air filter, and other than that, maybe drop by one of the auto parts stores that offer OBD scanning and have them check your codes. That or invest in a scan tool. The newest ones are pretty amazing with what they can do.

 

[tommudd]

NGK coppers only , coils or computer doesn"t like anything else

 

[Firefighterf18]

I will order those tonight

 

[Yosarian]

Running great in mine.
Have ya tried 'em, or is there something specific about the performance perameters of the plug that you feel are a problem?

 

[Firefighterf18]

I've try almost everything trying to figure this out. I've even try different grade of gas

 

[tommudd]

Running great in mine.

So far ...........

 

[Yosarian]

Ahhh, a kindred spirit.
It's not called Murphy's Law for 'nuthin. lol

 

[Firefighterf18]

I put the ngk Cooper plugs in and it still sounds and feels like a miss. But no mil light.

 

[LibertyTC]

Find someone with a snap on ultra scanner. Any misfires even random, can be viewed live while jeep is running.
It can take between 1000 to 1500 misfires to even set a code, go figure.
I've also replaced the TPS as it seemed to have a surge at around 1600 to 1700 rpm. Mopar TPS only fixed that.
What brand and part # of injectors were installed?

 

[Firefighterf18]

It was a set from rock auto.