OK... Time to ask experts!!!!!

[WyldWolf777]

I am SO exhausted & frustrated over my long drawn out rough idle & stalling in PARK issue!

History... Two months ago my 2006 Jeep Liberty 3.7L began having a very erratic idle but ONLY IN PARK. Then it developed a severe misfire plus had random intermittent sudden loss of power acceleration where it would bog down and almost nothing with pressing pedal to the floor then it would stall or slowly pick up pace as if nothing were wrong. Between myself & father in law we replaced all of the following trying to fix it.

*New fuel pump
*Every sensor that was plugged into the engine ( MAP, IDLE CONTROL VALVE, TPS, CRANKSHAFT, EGR, plus others)
* All coil packs
* All injectors
* New plugs
* 4 new oxygen sensors
* New starter
* Deleted converters thinking they may be clogged
* Brand new muffler thinking it may be restricted
* All new fuses / relays

And... After running it daily with the misfire because it is our sole vehicle and my wife had to get ti work 45 min away... It died.

Was told it has a bad valve...

So... Got a used 3.7 from junk yard with only 124K on it. It was from a 2008 Dodge Ram.

Got it professionally installed and got Jeep back. First test drive got 400 feet towards the end of my street and when I was braking to stop it stumbled and stalled! Then for the whole drive it was doing the exact same thing as the prior engine did with rough idle in park and bogging down / stalling. It has not misfired and had the blinking check engine light yet.

Took it back to shop and they ran diagnostic. I was told two oxygen sensors up front came back and needed to be set and programed to computer which my mechanic did. Also the fuel pump came back as bad as well. So bought a brand new pump and mechanic just installed it yesterday. Got Jeep back and it is STILL idling very rough in park way up then all the way down til' almost stalling then it stalls eventually.

I am wondering a few things now. Could having no cats be causing the erratic idle? Since the engine was out of a 2008 Dodge Ram does my 2006 liberty need a different ECU, or if not could my ECU be faulty all along causing the bad park idle?

Or anything else it could be? I find it absolutely astonishing it is doing exact same thing with a completely different engine!!!!

And finally... Very nice to meet you all and HAPPY NEW YEAR!

 

[lfhoward]

Wow! Sounds like you have covered a lot of bases. Sounds more than frustrating!

The 06 should have an idle air control valve (IAC) that regulates the air going into the throttle body at idle. If this valve gets gummed up it could make your engine stall or get bogged down at idle through lack of air for combustion. You could try to remove it and gently clean your IAC with throttle body cleaner and a soft toothbrush, or just replace it. It should be located on the throttle body if I remember correctly.

Note: On 07 and later 3.7's the IAC was eliminated because the throttle body was electronically controlled instead of by throttle cable. So, I'm betting they moved the dirty IAC over from your old 06 engine to the new 08 engine along with your 06 throttle body to make the swap work.

 

[WyldWolf777]

I put on a brand new IDLE VALVE as well, but thanks...

Also I forgot to mention ALL of the new parts were transferred to this replacement engine.

 

[WyldWolf777]

Anyone... Bueller...Bueller?

 

[JeepJeepster]

There is no such thing as programming 02 sensors to the PCM....

What diagnosing have you done? When it stalls, does it start right back? You should at least start with watching the fuel pressure to see what it does when its idling rough in park/whenever.

 

[WyldWolf777]

There is no such thing as programming 02 sensors to the PCM....

What diagnosing have you done? When it stalls, does it start right back? You should at least start with watching the fuel pressure to see what it does when its idling rough in park/whenever.

In park the idle surges high then super low where the exhaust sounds like a cammed hot rod then stalls eventually.

It starts right up every time after stalling. The battery is older and a few times when starting it has a very quick pause once the starter hits then turns the engine over but not like I remember when the battery was new. It used to be a more thorough firm strong turning without any pause.

A friend mentioned that if the battery was indeed weak it can cause a rough idle by draining almost all the current from the alternator as it is trying harder to charge. I am going to check it tomorrow and see if it is good. He said the voltage when running should be 13 - 13.8

 

[LibertyTC]

The correct spark plugs for the KK 3.7 engine requires NGK ZFR6F-11 and gap them at .043 inch.
Since you have the 08 engine now, is there a TPS sensor (throttle postion sensor) on the 08 ? IDK but on KJ's tps can cause surging along with Map sensor.
Battery yes get it load tested. What is the standing voltage after it sits overnight?
If you do need a new battery consider getting an AGM (absorb glass matt) They are longer lasting, deep cycle & fully sealed. Wont get terminal corrosion.
Exide Edge, Napa, Northstar & Odyssey. My Odyssey is still working fine at 10+years !

 

[WyldWolf777]

The correct spark plugs for the KK 3.7 engine requires NGK ZFR6F-11 and gap them at .043 inch.
Since you have the 08 engine now, is there a TPS sensor (throttle postion sensor) on the 08 ? IDK but on KJ's tps can cause surging along with Map sensor.
Battery yes get it load tested. What is the standing voltage after it sits overnight?
If you do need a new battery consider getting an AGM (absorb glass matt) They are longer lasting, deep cycle & fully sealed. Wont get terminal corrosion.
Exide Edge, Napa, Northstar & Odyssey. My Odyssey is still working fine at 10+years !

This is great help thanks! I put Champion plugs in the 2008 3.7 I have now. So... Tonight I purchased 6 of the correct NGK plugs you recommended. The jeep is still at the shop being tested & diagnosed and I will replace the plugs and do a battery voltage test once I get it back. I also ordered two new catalytic converters because it stinks and is louder than I like without them. Plus maybe it will help the ECU read the air better to adjust things. I do not know if it has the TPS but will look for that too to see if yes or no. Much appreciated thx!

 

[Ksat]

The oxygen sensors, especially the upstreams, need to be NTK/Mopar brand. Anything else and you'll potentially be chasing ghosts. Btw, as jeepster stated, O2's do not need to be "programed to the computer." To answer your question, no, a lack of cats will not cause a bad idle. Also, a weak battery should not cause an erratic idle.

You need to read the codes/look at the live data and freeze frame data on a scan tool to see what's really going on otherwise you'll just be swapping out parts forever. Based on what you've said in your posts, It sounds like finding another mechanic may be in order.

 

[justjeeps]

Perhaps try spraying some carb cleaner around the intake to see if there may be a some sort of vacuum leak. Check the exhaust for leaks as well but one can usually here them.

Does it shift ok because sometimes a issue with the trans can cause stalling. Did you replace the coils or at least suspect ones.

just a thought - Perasonally gave up on jeep after the last rodeo with 2002 but I really do miss the comfortable seats in the limited editions.

 

[WyldWolf777]

I bought a set of 4 O2 sensors, cheapest I could find off Ebay. I figured they all work the same. Also this is the third time it has been over at this shop! Each time we get it back supposedly fixed it does the same rough idle stalling thing so yes maybe time to take it somewhere else!

Yes I changed ALL the coil packs & injectors. All new

 

[WyldWolf777]

Also... Should have been a red flag when the mechanic told me he needed to program the O2 sensors. At first I was like ummmm OK? Really? But I figured he knows more than me...

 

[WyldWolf777]

Perhaps try spraying some carb cleaner around the intake to see if there may be a some sort of vacuum leak. Check the exhaust for leaks as well but one can usually here them.

Does it shift ok because sometimes a issue with the trans can cause stalling. Did you replace the coils or at least suspect ones.

just a thought - Perasonally gave up on jeep after the last rodeo with 2002 but I really do miss the comfortable seats in the limited editions.

Transmission shifts fine, but will check fluid in case. Will try your other suggestions too

 

[WyldWolf777]

Bought a code scanner... Pulled 4 codes.

Codes



P0443 - Evap Purge Valve

P0113 - IAT sensor

P0138 - Both Front Oxygen Sensors

P0158 - Both Rear Oxygen Sensors

I found where the IAT sensor "should be" on the intake but it seems like it is either capped off or not required for the 2008 3.7?

Also can having deleted cats make all 4 oxygen sensors read off and the ECM think they are faulty?

 

[Ksat]

I bought a set of 4 O2 sensors, cheapest I could find off Ebay. I figured they all work the same.

They don't all work the same, unfortunately. Chrysler in particular uses a voltage bias on the signal wire in order for the PCM to do a monitor check for the O2 sensor heater, as required by OBD II.

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Not all O2's play nice with this setup, even brand name ones (like Bosch), have caused many headaches for techs.

NTKs are what you need. They aren't much more $ than most other manufacturers, anyway.

 

[Ksat]

As far as the codes:

With purge valve, remove the electrical connector on the purge valve solenoid, apply, then disconnect 12V/ground and see if the valve is indeed allowing/blocking air flow through it as it should.

With the IAT code, if your scanner has live data ability, look for the IAT PID and see what temperature it's reporting. Temp when engine is cold should be ambient air temp and temp when engine is warmed up should be some degrees higher.

Testing for the front O2s I won't go into, because you may not have the proper ones installed.

Having no cats would not affect the front O2s. At most, it would just trigger 'below threshold' codes for both banks. On some vehicles. data the PCM receives from the rear O2s is used fine tune long term fuel trim values, but I'm not sure if that's done on the Lib. A misreporting rear O2 might cause a closed loop fault to display alongside the short term fuel trims, but the PCM will still rely on input it receives from the front O2s.

 

[WyldWolf777]

Ok gonna grab NTK O2 sensors but have a question. With the Liberty being a 2006 with 2006 wiring & ECU and the replacement 3.7 being a 2008 do I order 2006 liberty O2 sensors or 2008? Or it does not matter?

Also will perform the purge test in the morning thanks for info!

 

[tommudd]

Computer is set up for your 06 , so go with what should be in there

 

[WyldWolf777]

Computer is set up for your 06 , so go with what should be in there

 

[WyldWolf777]

Ok thanks