Jeep Enthusiast Forums banner

02 Liberty surge/stall

6K views 20 replies 6 participants last post by  LastMopar 
#1 · (Edited)
I have an 02 Jeep Liberty Sport 4WD 3.7 that seems to be devouring very good mechanics (0 for 6). With warm engine, whenever I come to a stop, the RPM’s drop to about 500 then surge to about 1300 and then engine dies. Occasionally it surges multiple times before dying. Shifting to neutral approaching stops does not help. Sometimes engine has a slight hesitation (minor issue) just above idle position and other times throttle response is perfect. There are NO codes! Possible clue: Problem is somewhat minimized (not resolved) when slight vacuum leak is created at throttle body. Basically, this vacuum experiment results in smaller surge and engine sometimes smooths out and idles properly after the initial surge. Still, problem remains at each subsequent stop.

This is a brand new re-manufactured engine from O’Reilly’s. I have replaced or tried the following parts/sensors: Intake, IAC, TPS, MAP, PCV, Upstream O2’s, Plugs, Coil Packs, Fuel Filter. Have had dealership flash and reprogram ECM, tried 2 other ECM’s from salvage. We’ve thoroughly cleaned Throttle Body and tried replacement from salvage. We’ve checked voltages, vacuum pressures, fuel pressures. Engine will also have an occasional slight random misfire (ruff idle) which immediately smooths out when lightly misting fuel (carb cleaner) directly into throttle body. All systems are operating within specified parameters and again, no codes!?!?

I purchased this vehicle from a legit private party with 150k miles and it and ran perfect for 5 weeks until the catastrophic engine failure (valve seals). I accidentally ordered an 04 engine and realized before installation. Engine manufacturer (Power Torque) said it would work and we should go ahead and install it. Obviously, this engine was not compatible and resulted in massive backfire. They apologized, paid labor costs and exchanged the engine. All of these external parts, including intake, were replaced after 2nd replacement engine was installed and idle problems presented. Desperate for Serious Advice!!!
 
See less See more
#2 ·
Yikes that's a tough one. Sounds like you've been very thorough so I'm probably not much help. Only thing I could think of trying would be to get a live data scan while driving and it is acting up. Maybe something will show on there. Only other thing is what brand of replacement parts and sensors are you using? From my experience, these things are real fussy with sensors and only Mopar sensors have worked correctly for me.
 
#3 ·
Thank you 02blue.
After stubbornly trying cheaper parts first, we returned them and got Mopar stuff, except for the actual engine. Nothing shown on the drive scan? Forgot to mention: bought new Champion Plugs and tried new Cam and Crank sensors too. Smoked the engine and found no leaks. There is a small EVAP leak near gas fill tube. Could that be the problem?
 
#4 ·
I doubt that small of an evap leak would do it without throwing a code. What year engine was this that was rebuilt to fit your 02? As you probably know now, any 3.7 up to around 2012 will fit with the right reluctor rings swapped in for the cam and crank sensors. Long shot, and don't really know if it would produce the symptoms you are experiencing, but I think 08 and after 3.7 engines had an EGR system. Any ports need to be blocked off for our 02 KJs (and also my 05) as we don't have this system.

Did you reuse your original 02 exhaust manifolds? I think the factory 02 exhaust manifolds will block this but not sure if a plate is needed or available. If it wasn't blocked I'm thinking you may have a big exhaust leak. You won't get an EGR code since our computer wouldn't look for it. I'm assuming the vacuum end of it would be in the intake so you should be okay with your 02 intake.

Again, just a long shot. Maybe someone else out there more mechanically inclined will be along soon.
 
#5 ·
Evap leak isn't going to cause the issues you have, and whoever did the smoke test probably did not do what is required to test a vehicle with an LDP, so likely no real leak. Oreillys engines are not the best out there either, but I don't think that is your issue, or likely isn't. Need to perform voltage drop tests on powers, grounds, etc. I suspect a missing ground, but without having my scan tool hooked to it, reviewing fuel trims, etc, I am speculating. There are shops that can figure it out, but since they are coming in behind someone else's work, you should expect to pay a measurable amount more for diag time. If it rolled into our shop, we'd want receipts, lists of stuff done, source of parts, etc, and no less than 3hrs diag time and leave it with us, we will call you later, like in a couple of weeks.
 
#6 ·
I know that you mentioned you checked the fuel pressure, but just to make sure... You have to check the pressure three times: 1) With the key in the 'On' position but the engine not running. 2) With the engine running. 3) After shutting off the engine, to see if the system properly holds pressure for a while.
For the '02, proper fuel pressure should be 49.2 +/- 5 psi.

I had issues with the fuel pump in my last vehicle ('03 Explorer), and the occasional surging and stalling at stop signs and lights was one of the symptoms. If the pressure was tested immediately after starting the engine, the readings would be perfectly fine. But after a couple of minutes the pressure would drop a bit, and when shutting off the engine it would drop to 0 psi right away.

What are your fuel trims at? When I had these issues, it took several weeks before it actually started throwing codes at me for bad fuel trims.
 
#7 · (Edited)
I purchased a Crate Motor from O'reilly's manufactured by Power torque. It is the proper 02 engine. As stated previously, I accidentally ordered an 04 engine and realized before installation. Engine manufacturer (Power Torque) said it would work and we should go ahead and install it. At that time, I was unaware of the 32 tooth vs. 16 tooth reluctor wheel. Obviously, this engine was not compatible and resulted in massive backfire. They apologized, paid labor costs and exchanged the engine. I'm wondering if the issues I now have are somehow a result of the backfire because they weren't present before. We have checked or replaced so many things.
 
#9 ·
Any updates? I posted my similar issue in this forum for I have an 02 with the original 3.7 v6 at 123k miles. Had the vehicle for 2 years and ran great, gave the kj to my gf and immediately had misfires, changed coil pack A. New Battery and alternator 6 months ago when the alternator failed. Cleaned throttle body with sea foam for maintenance. Next had a catalytic converter below threshold code pop up, used cataclean and the code immediately went away. A few weeks later the Kj is stalling at a red light coming to a stop and the rpms drop below 500. Any solutions to your issue?
 
#10 ·
I'm wondering if you and the OP both have cat issues. Once they go bad there is nothing to do but replace. Of course you want to be absolutely sure that this is the case. Cataclean may work for a while but it isn't really a fix despite the advertising. Unless you fix the reason for the contamination, you'll probably be replacing them again.
 
#11 ·
GreyWj93, Thanks for your input. I'm pretty certain its not a cat issue. No helpful updates to report. Drove around for two hours with scanner connected checking everything. Vehicle runs beautifully while driving but dies at at a stop or near stop. Occasionally at stop, it will surge repeatedly without dying. Additionally there have been times where it would surge once or twice then idle smooth.
 
#12 ·
Oh ok your symptoms sound a tad different from mine. My kj seems to stall before operating temp while coming to a stop then once at normal temp runs fine coming to a stop. My next point of attack will be the battery because I was stupid and baught an autocraft silver which is rated at 525CCA. Given a few months and cold temps is probably making the battery output weaker then specifications and messing with the cpu. That or a crank shaft position sensor will be next.
 
#15 ·
Mine ended up being low on transmission fluid due to a leaking seal. Added 5 quarts of ATF+4 and the engine stopped stalling coming to a stop before operating temp. Replacing pan and filter this week. Didn't see anything about it in your original post. Best of Luck!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top