04 Liberty 3.7 2WD, Really rough idle cold

[Ed McMeans]

Loving this forum. A month or so ago I picked up this 04 liberty, 130,000 miles on it. When I start it cold, the whole car shakes really bad. This is in neutral and also in gear. When the engine warms up and idling, it's pretty good, some slight roughness, but acceptable anyhow. Tach is steady when the car is shaking, and no CEL is showing up. I've cleaned the throttle body, replaced the IAC, spark plugs, and the IAT, no change. When idling and warmed up, if I rev up the engine and hold it at the cold idle rpm, still no shaking, just bad when it's cold. Any thoughts? Thanks for any help, appreciate it. The car has excellent acceleration power.

 

[tommudd]

To start NGK copper plugs
reason for asking is one was brought to me guy just bought, rough idle etc
started by checking plugs, had some junk Plats in it gapped at .55
threw a set of NGK coppers in and ran like brand new , guy was amazed plugs could make that much difference
so,.........

 

[Ed McMeans]

To start NGK copper plugs
reason for asking is one was brought to me guy just bought, rough idle etc
started by checking plugs, had some junk Plats in it gapped at .55
threw a set of NGK coppers in and ran like brand new , guy was amazed plugs could make that much difference
so,.........

 

[Ed McMeans]

Thanks, That was the first thing I tried, put in new NGK coppers, didn't make a difference. The thing that puzzles me is, why is it so much worse cold than after it warms up? I'm thinking of replacing the upstream O2 sensors, but hate to just throw more parts at it.

 

[LibertyTC]

How cold is it outside where you are? Using synthetic 5W-30?

 

[Ed McMeans]

How cold is it outside where you are? Using synthetic 5W-30?

Actually, cold here in Southern California isn't very cold, about 50 degrees. (I grew up in Northern Michigan where cold meant cold, finally got out of there) First thing I done on the car was to
change the oil to 5-30 full synthetic.

 

[LibertyTC]

Is pcv clean ?
What you may consider checking is for misfires.
Snap on scanner can see random misfires at idle live.
My 04 when cold shakes slightly not bad though.

 

[Ed McMeans]

One odd thing that I'll have to try again just to see if it's real: I disconnected the battery overnight a while ago, and next morning connected it and started the car.

Is pcv clean ?
What you may consider checking is for misfires.
Snap on scanner can see random misfires at idle live.
My 04 when cold shakes slightly not bad though.

 

[Ed McMeans]

I took the pcv valve off and shook it, it rattled, so I assume it's OK. Wouldn't a misfire throw a code and set a CEL?

 

[tommudd]

Have you had all the codes checked , well checked for any codes
simple to do on an 04 with the on and off switch trick

 

[Ed McMeans]

Have you had all the codes checked , well checked for any codes
simple to do on an 04 with the on and off switch trick

 

[Ed McMeans]

I have a "scangauge" that I keep plugged in to the OBD. Gives me several realtime info things. Also checks for and clears codes, doesn't show any. I imagine a more sophisticated scan would do more, but I havn't taken it to a shop that can do that. $$$.

 

[LibertyTC]

I took the pcv valve off and shook it, it rattled, so I assume it's OK. Wouldn't a misfire throw a code and set a CEL?

Misfires= Computer may not set a code if it is random and It can take 1500 to 2000 misfires to turn on a misfire code.
I ended Up Changing out all the coil packs, which made it run better, would recommend Mopar coil packs, but still slight shake at idle while it warms up.
See post # 20 is it stem seals or fuel related?I still do know know. At the time if the Jeep sat for 4 days without starting I was seeing a slight blue oil out tailpipe.
One thing is also certain since adding star-brite Star-Tron an Enzyme ethanol fuel treatment the Jeep runs so much better!
https://www.jeepkj.com/threads/3-7-engine-slight-shake.57700/
Viewing live data when cold from the Snap on scanner for your Jeep, is the only way to know how many hits of misfires you may be viewing!

You must be registered for see images attach

 

[Ed McMeans]

If there is a misfire problem, would it cause idle with engine cold to be much much rougher than idle with it warmed up?

 

[LibertyTC]

Yes.

 

[Shane Giggie]

If there is a misfire problem, would it cause idle with engine cold to be much much rougher than idle with it warmed up?

Definitely.

 

[HoosierJeeper]

Are the coil packs in good shape? There's been a time or two here where someone has had cracked coil packs and overnight condensation would get in them and they'd get a rough idle at a cold start but would be better later.

 

[Ed McMeans]

Don't know about the coil packs condition. Maybe I could buy one and switch them out one at a time to check that?

 

[Ed McMeans]

Don't know about the coil packs condition. Maybe I could buy one and switch them out one at a time to check that?

 

[Ed McMeans]

Thanks, That was the first thing I tried, put in new NGK coppers, didn't make a difference. The thing that puzzles me is, why is it so much worse cold than after it warms up? I'm thinking of replacing the upstream O2 sensors, but hate to just throw more parts at it.