96 Jeep Grand Cherokee Laredo 4.0 Inline 6 Stalling 181K No codes

jeepsgonewild · 07-08-2009, 03:48 PM

What I drive: 96 Jeep GC Laredo, 4.0L Inline 6, Automatic, 181,000 miles.

I'm having a major and frustrating issue with stalling and with no codes, but drives very strong.

Here's my problem on idle: starts up perfectly, idles perfectly, hot or cold engine, and if I just observe what happens on idle, the rpm will rise suddenly out of nowhere, like someone has hit the accelerator peddle.

Here's my problem while driving: While driving, the rpm will drop off very quickly, feels like something is pulling me, then it will resume normally. Sometimes it resumes and sometimes it stalls. It is completely random and scary.

I am getting no codes. Mechanics don't want to deal with me because they don't have a code to work from!

So here is what I have replaced: IAC, TPS, crank sensor, coolant temp sensor, ignition coil, air and fuel filter. Recently replaced fuel pump.

Hope I can figure this out so I can post the fix here IF I can fix it. Thanks and appreciate your forum!!

Brad Cowin · 07-08-2009, 05:12 PM

This has plagued me since I bought mine (96 I6 122k). Same exact ****.

I went and messed around with the PCM. Just making sure everything is tight, connected right, etc and it seems to have made a noticeable difference. Maybe about 20% less trying to stall while driving and probably about 30% stalling at idle. If I didnt just lift it and get new tires and wheels, I would probably replace the PCM.

With all the stuff you've already replaced I would take a look at the PCM.

jlindseyjr · 07-08-2009, 06:23 PM

You could try this:

http://www.jeepforum.com/forum/showt...ght=dielectric

It will cost you less than $10

rooster51 · 07-08-2009, 08:43 PM

check camshaft positioning sensor and brace for possible PCU replacement of troubleshooting.

jeepsgonewild · 07-09-2009, 07:17 PM

@Brad Cowin, I am also thinking it is the PCM since I have read that the circuit board can short out and no codes appear. So I might get a brand new one, but they are expensive I found one for $196.99 at Autozone or I might find a used one.

@jlindseyjr, I will definitely try cleaning out the PCM for starters and see what happens.

@rooster51, will check the camshaft positioning sensor if all else fails.

Also, here is another thing that I have noticed and it is consistent every time I drive. When the coolant/engine temp hits exactly between 100 and 210 degrees... I'm guessing that is 150 degrees, it wants to stall anytime at or before that.... so when the engine is at a nice and hot 170-190 degrees it will never stall out, I was driving for an hour today and it is always perfect when the engine is nice and hot. Weird I know...but it is something that I have noticed. I dropped off my Jeep to have my mechanic take another look so hopefully I should know tomorrow.

jeepsgonewild · 07-11-2009, 07:55 PM

Air Intake Temp Sensor
Oxygen Sensors
EGR Valve

I was also wondering if anyone had a picture of the locations of the above?

My jeep has been stalling only before 150* range but after it has reached maximum temp near 190 it does not stall what so ever, I have confirmed this.

I'm beginning to think maybe it's the PCM because I'm getting no codes at all. You would think a faulty PCM would make my Jeep stall no matter the temp.

So do you think a faulty Oxygen sensor would produce stalls?

Also, I have read this and sounds like it's feasible it might be these sensors, but I really don't want to replace a another working part it's costing way too much!

---------------------------------------------------------------------
"Air Intake Temp Sensor - Helps correct air fuel ratio by measuring the temp of the air coming through the intake

Oxygen Sensor - Largest determinate of air/fuel ratio after the vehicle almost reaches operating temp which is approx 160 degrees

EGR Valve - 5.2 Liters are known for these failing, they redirect a small amount of exhaust gases back into the intake manifold for re-burning (emissions thing). Sometimes they get stuck closed and allow for too much exhaust gas back into the manifold. But usually this would cause very poor performance as well as shuddering and stalling"

jeepsgonewild · 07-12-2009, 12:32 PM

I did one more cheap fix... I've put in fresh new spark plugs and wires. No hiccups today, but I will smack myself if this was it the entire time. I don't think so but who knows. The old spark plugs were a little fouled and were due anyways. We'll see......

jeep0312 · 07-12-2009, 12:41 PM

again with the computer! i replaced everything sensor wise in my jeep with a 4.0l! i finally putr the 200$ behind me and got a computer from autozone and it "knock on wood" hasnt hicuped or anything for 2 weeks!

Hope this helps!

jeep0312 · 07-12-2009, 01:04 PM

BTW i also have a 1996 Jeep grand Cherokee Laredo inline 6 4.0 but only mine went at about 200k miles but started messing with it and it went completely at 210k miles!

jeepsgonewild · 07-13-2009, 03:10 PM

@jeep0312

You're saying computer, however, I'm saying fuel pump. Why?

Because every single time I idle, my jeeps stalls as it hits 150*.

Once the engine is HOT around maximum temp of 190*, it does not stall, I know this for a fact.

How does this come to a computer issue?

In the morning, I just don't have time to idle since it's not hot enough to bring temp so quickly, but in the afternoon, I just idle until it stalls out a couple times (around 150*), then wait for 190*, then drive off and it's perfectly fine.

jeep0312 · 07-13-2009, 03:40 PM

then the way to figure out if it is fuel related use a pressure gauge. im not sure what the pressure at on position is or the idle pressure is.

rooster51 · 07-15-2009, 10:40 PM

Quote:

Originally Posted by jeep0312

again with the computer! i replaced everything sensor wise in my jeep with a 4.0l! i finally putr the 200$ behind me and got a computer from autozone and it "knock on wood" hasnt hicuped or anything for 2 weeks!

Hope this helps!

Congrats, I know how relieved you feel now.

Be-O-Be · 07-16-2009, 01:29 AM

i believe if your fuel pump is bad then it will completely die, no more run until you replace

jeep0312 · 07-16-2009, 03:41 PM

Quote:

Originally Posted by rooster51

Congrats, I know how relieved you feel now.

OH!!! I feel so relieved!

jeepsgonewild · 07-18-2009, 09:35 AM

update: I'm done guessing with changing sensors and everthing so I brought it to a jeep dealer. At first they drove it and said they see no problems. Of course, right?? So I take a look at the temp gauge and it was a little above 100, so I was like well, it didn't stall because you did not drive it long it for the temp to climb.

So my vehicle was ready for me to drive off and I was just going to idle a bit for the temp to hit 150 and low and behold it stalls so I shut it off immediately and walk back in and ask for the mechanic to witness it stalling, and at this point I'm desparately hoping it to stall. So we idle a little bit and it just shuts off.

So now that the mechanic has witnessed it stalling, I will have to further diagnose this issue another day. They are stumped. They have possible reasons but it just points to guessing.

It could very well be a computer issue, but what if it isn't? It will just be a guessing game.

I have no idea why that once the engine has warmed up for a while I can drive it all day and not one issue.

I also was not charged so I like that, and they did a recall (no charge of course) for a floor shifter and shifting is improved, so it wasn't a total loss of my time.

Wouldn't you say if it was a computer issue it would act up no matter what?