Yet another stalling (almost) issue...

[Stud Muffin]

Hi all,

I have a '97 Grand Cherokee with 2WD and a 4.0 engine.

I am having problems with the car occasionally stalling when at idle. I'll try to bullet my findings thus far:

As background, I commute on the LA freeway about 1.5 hours each way every day. Probably the first 10 minutes of this is city driving. The next 10 is freeway at normal freeway speeds. The next 30-35 is stop and go, the rest is at normal freeway speeds.

When I stop on the freeway (or in town, for that matter) during the "trouble period", it pretty much idles roughly, tries to die, sometimes does, sometimes does not.

1) This happens only from startup to approximately 35-45 minutes of driving time (my "trouble period"). After this time driving, the car works fine (a bit rougher than in the old days, but I just figured that was due to old age...it hasn't really changed in the past year).

2) Sometimes it idles fine, most times rough, every once in a while it dies. Usually it starts right up when I restart it, and resumes operation as is typical during the "problem period". Every once in a while (twice a week?) it takes a while trying. During this time it may (a) turn over quickly without catching for about 20 seconds or so (b) start and idle extremely roughly, and making a smell not really like fuel, but not really like "clean exhaust" either or (c) start right back up after turning over a few seconds.

3) While idling, when I change between drive and park, or neutral, the RPM's go down, then back up. I notice this more markedly going from drive to neutral or park, not so much going back the other way.

4) If I give it gas when it starts to die, it usually picks back up and goes on as before. Every once in a great while, the extra pedal results in what sounds like "dieseling", and it will either work through that and run again as usual, or will die and I'll have to restart it. Most times the extra pedal puts things right again.

5) I seem to be getting better gas mileage since the problem has become more regular. over the past year, my mileage went down (according to the on-board computer) to average about 14.6 or so. For the past couple weeks, since the problem has grown more persistent and regular, my MPG is closer to 15.8 or so (sound like I'm running leaner, right?).

6) I just replaced the IAC motor, thinking from the many, many, many forum threads on this type of issue would suggest, but it made absolutely no difference.

7) The problems seems more likely to occur when the temperature of the outside air at startup time is about 65 or so. The past two days it has been at 80 degrees or above here, and there really hasn't been a time when the car actually felt like it was going to die (though it runs poorly enough to be noticed that something is still not "right"). This is interesting to me because the problem goes away (the idle issue, not so much the not-quite-right running) also after 45 minutes of driving.

I don't think the issue is related to ENGINE temperature, because it has LONG since gotten to regular operating temperature by the time 45 minutes of driving has gone by.

My thoughts are, in order of the likely order of parts replacement (a) The MAP sensor and (b) the coil.

I don't think it is the TPS, because there is no "dead spot" in the range of pedal travel.

I am thinking MAP sensor because the poor performance seems to be during times of low engine load. My understanding (limited as it is) of the MAP sensor is that it is a glorified VACUUM guage. And indeed, the way the jeep is running reminds me of the way my '67 Cougar runs when there is a vacuum leak (at least at idle).

Any thoughts? Hopefully I have provided enough info for someone to think to themselves "Mine did that, the poor bastard needs to replace his jeep's xxxxx" where xxxxx is the part to replace. *LOL*

[dksob81]

Originally Posted by Stud Muffin

Hi all,

I have a '97 Grand Cherokee with 2WD and a 4.0 engine.

I am having problems with the car occasionally stalling when at idle. I'll try to bullet my findings thus far:

As background, I commute on the LA freeway about 1.5 hours each way every day. Probably the first 10 minutes of this is city driving. The next 10 is freeway at normal freeway speeds. The next 30-35 is stop and go, the rest is at normal freeway speeds.

When I stop on the freeway (or in town, for that matter) during the "trouble period", it pretty much idles roughly, tries to die, sometimes does, sometimes does not.

1) This happens only from startup to approximately 35-45 minutes of driving time (my "trouble period"). After this time driving, the car works fine (a bit rougher than in the old days, but I just figured that was due to old age...it hasn't really changed in the past year).

2) Sometimes it idles fine, most times rough, every once in a while it dies. Usually it starts right up when I restart it, and resumes operation as is typical during the "problem period". Every once in a while (twice a week?) it takes a while trying. During this time it may (a) turn over quickly without catching for about 20 seconds or so (b) start and idle extremely roughly, and making a smell not really like fuel, but not really like "clean exhaust" either or (c) start right back up after turning over a few seconds.

3) While idling, when I change between drive and park, or neutral, the RPM's go down, then back up. I notice this more markedly going from drive to neutral or park, not so much going back the other way.

4) If I give it gas when it starts to die, it usually picks back up and goes on as before. Every once in a great while, the extra pedal results in what sounds like "dieseling", and it will either work through that and run again as usual, or will die and I'll have to restart it. Most times the extra pedal puts things right again.

5) I seem to be getting better gas mileage since the problem has become more regular. over the past year, my mileage went down (according to the on-board computer) to average about 14.6 or so. For the past couple weeks, since the problem has grown more persistent and regular, my MPG is closer to 15.8 or so (sound like I'm running leaner, right?).

6) I just replaced the IAC motor, thinking from the many, many, many forum threads on this type of issue would suggest, but it made absolutely no difference.

7) The problems seems more likely to occur when the temperature of the outside air at startup time is about 65 or so. The past two days it has been at 80 degrees or above here, and there really hasn't been a time when the car actually felt like it was going to die (though it runs poorly enough to be noticed that something is still not "right"). This is interesting to me because the problem goes away (the idle issue, not so much the not-quite-right running) also after 45 minutes of driving.

I don't think the issue is related to ENGINE temperature, because it has LONG since gotten to regular operating temperature by the time 45 minutes of driving has gone by.

My thoughts are, in order of the likely order of parts replacement (a) The MAP sensor and (b) the coil.

I don't think it is the TPS, because there is no "dead spot" in the range of pedal travel.

I am thinking MAP sensor because the poor performance seems to be during times of low engine load. My understanding (limited as it is) of the MAP sensor is that it is a glorified VACUUM guage. And indeed, the way the jeep is running reminds me of the way my '67 Cougar runs when there is a vacuum leak (at least at idle).

Any thoughts? Hopefully I have provided enough info for someone to think to themselves "Mine did that, the poor bastard needs to replace his jeep's xxxxx" where xxxxx is the part to replace. *LOL*

This sounds just like a bad IAC Valve - 1 did you disconnect the battery before you removed/replaced the IAC Valve? 2 did you adjust it according to the instructions?

[Stud Muffin]

Originally Posted by dksob81

This sounds just like a bad IAC Valve - 1 did you disconnect the battery before you removed/replaced the IAC Valve? 2 did you adjust it according to the instructions?

Yeah, that's what I thought, and why I replaced that part first. *L* Oh well...

Yeah, I did disconnect the battery, for probably about a half hour, give or take. During the time I replaced the IAC motor, anyway.

I followed the instructions, but all they really said was "if it sticks out more than <yada,yada> inches, then you need to adjust it smaller (can't remember what the <yada,yada> was...might have been 1 1/8 inches), but the plunger was shorter than that, and since it didn't say to make it that long, I left it shorter (as it came from the parts place).

I put on a NAPA IAC, thinking they generally have the better OTC parts than places like AutoZone, Kragen, or Pep Boys. Is this something that is better purchased from the dealer?

Interestingly enough, though it does not yet run like it should, the past two days I have driven it, it has not died at idle on the freeway. I can still feel it running rough(er than usual) but it does not stumble and die (at least so far). Could it be that the computer is learning how to set itself after several days? I know that to "clear" the computer's memory about current settings from sensors is why the battery is disconnected, but would not expect the "learning" to result in the initial reconnection of battery and driving after the IAC motor replacement to take this long.

I'll see how it does on the way home (and until payday!) but am just curious about (assuming it is not yet fixed) the deal with NAPA verses Dealership purchase for this part (I usually get sensors from the dealer, just to be safe, this time I thought I'd try NAPA).

Thanks for your input so far!!!

[Stud Muffin]

I was also thinking....what about the engine temp sensor on the front of the engine? I understand (from forums and many online searches) that there is a separate engine temp sensor for the 'puter and a different one for the gauge? Hmmmm....

Originally Posted by some poster on another, evil, forum in response to someone else's idle question

So, you're saying cold idle is too low? Runs OK after it warms up? If so, check out the engine temp sensor on the front of the engine--the one that feeds the ECM. The one on the back of the head feeds the temp sensor--at least that's where the are on the early 4.0's.
The ECM varies fuel mixture proportionately to the resistance of the temp sensor--it's the modern-day equivalent of a choke--cold engine=more fuel. As the engine warms up, the extra fuel is reduced. The temp sensor is also instrumental in setting cold idle speed. Cold engine=high idle.
Without cold enrichment and higher idle speed, you could experience stumble and hesitation until the engine warms up.

Does this sound plausible?

I suppose I could look into the book and see where it is. If I'm just tossing money at it (no C.E.S. light/codes, no data sniffer) maybe the temp sensor would be a cheaper option to check than getting a new dealer-supplied IAC?

Any thoughts?

The only thing that makes me hesitate on this one is that it continues for quite a while after the gauge on the dash says I have reached operating temperature.

[dksob81]

Originally Posted by Stud Muffin

I was also thinking....what about the engine temp sensor on the front of the engine? I understand (from forums and many online searches) that there is a separate engine temp sensor for the 'puter and a different one for the gauge? Hmmmm....Does this sound plausible?

I suppose I could look into the book and see where it is. If I'm just tossing money at it (no C.E.S. light/codes, no data sniffer) maybe the temp sensor would be a cheaper option to check than getting a new dealer-supplied IAC?

Any thoughts?

The only thing that makes me hesitate on this one is that it continues for quite a while after the gauge on the dash says I have reached operating temperature.

I doubt it's the temp sensor. What do you mean by "no C.E.S. light/codes, no data sniffer"?

I don't think you got a bad part from NAPA, although plausible, they are relatively good parts, did the part have a warranty ussually electrical parts like this carry a 90 warranty, if so I would take it back get a new one, and this time set the IAC valve at 1 1/8" from the inside of the pating surface to the tip of the plunger. Even if it didn't have a warranty it is a good idea to disconnect the battery, pull the IAC Valve off, check on the inside of the IAC bore for any dirt or carbon build up and set the AIC at 1 1/8".

[Stud Muffin]

Originally Posted by dksob81

I doubt it's the temp sensor. What do you mean by "no C.E.S. light/codes, no data sniffer"?

I don't think you got a bad part from NAPA, although plausible, they are relatively good parts, did the part have a warranty ussually electrical parts like this carry a 90 warranty, if so I would take it back get a new one, and this time set the IAC valve at 1 1/8" from the inside of the pating surface to the tip of the plunger. Even if it didn't have a warranty it is a good idea to disconnect the battery, pull the IAC Valve off, check on the inside of the IAC bore for any dirt or carbon build up and set the AIC at 1 1/8".

I just mean no "Service Engine Soon" (just added the "C" to the beginning to throw you off *blush*) or a reader to read any codes that might be there but not setting off the SES light on the dash.

Unfortunately, I tossed both the isntructions and the reciept, since I was POSITIVE this was the issue (you'd think I'da learned after many newer cars and 3 classic car restorations to keep that stuff until it is verified "fixed", but I guess everyone needs to be stupid once in a while).

I will do the IAC thing (disconnect battery, take it off, adjust to 1-1/8", reinstall, reconnect)...MAY have to wait until this weekend (or until it leaves me stranded at the side of the road *LOL*)...I have no garage light at the moment...and it's been getting dark pretty early these past coupla weeks.

[Stud Muffin]

Okee-dokee, back again.

I finally got back to it last weekend and took out the new sensor, scrubbed and cleaned the #@$)(*@# out of the IAC body, readjusted the plunger, and stuck it back in.

Alas, no change.

So, now it is starting to die/falter more often. So I suppose sooner or later it will leave me stranded and then I will know for sure what it is *LOL* Hopefully y'all can help me before I get to that point.

Lately it has started to stumble and almost stall when I come to a stop even after over an hour and a half of driving. When I am at-speed, there don't seem to be any problems.

A couple nights ago, I took off and just after leaving the curb it died. I started back up right away. Then about another 10 yards down the road, it died. Had to crank it for a loooong time this time before it started up. Drove around the corner, it sputters, diesels for a few long seconds, then died. I tried to start it, but no go. I smell fuel...feels and smells like a flooded engine. So I wait. try it again after a minute or so. No start...lots of turning over, no start. So I wait again, and start thinking about reaching for my Auto Club card. Try again, it starts up. Before I leave the curb, it starts dieseling again. I cut the ignition off (noticing that it seems to take longer to start up after a incidence of the dieseling - as opposed to an easy start after it just dies without dieseling) I decide to tempt fate and go on my merry way. Travelling along at 20-25, it sputters a few times, then runs fine. More sputtering for the next couple miles. Then it is fine for the remainder of my drive time, and even while waiting in line in the KFC drive-through and idling.

When the car does it's Dieseling thing after sputtering and trying to decide if it wants to die or not, I can sometimes smell a faint odor of gas, but more often an odd burnt smell that is probably partially burnt fuel? I dunno. Odd smell, but I assume gas and exhaust.

I think at this time maybe it's an ignition-side issue, because it seems like ignition when it gets to dieseling when it faulters - though sometimes it just dies without the dieseling.

I am almost to the point of taking it to a repair shop, but I am afraid they will just fix by replacement - - I have no idea if non-dealer shops can use a computer reader machine sufficiently well to diagnose the actual problem.

I would much rather fix myself if possible (obviously).

This weekend I am thinking of replacing the Coil and/or the Crankshaft position sensor, but really hate to toss money after parts.

I don't know if a bad IAC could cause the dieseling.

It's possible that the new IAC is bad, I suppose, or that I messed it up by not adjusting it to 1-1/8 inches initially, then doing that adjustment the second time around (especially since when I took it out the second time it was extended more than it was when I put it in new). I'm afraid it's possible that I adjusted it to be too SHORT now, to close all the way...but if so, I don't know if that would cause my current issues.

I don't mind re-replacing the IAC if that sounds like it could still be the issue, but every time I see something on a forum about this problem, I think "hey, yeah, that sounds like it could be the problem" and then the more I think about it, it doesn't quite fit with my issue.

On a separate, related issue...one time during the battle on the way to KFC (LOL) I did see the orange square light up in the engine part of the on-board-display console above my console, but it quickly turned off, and no text was displayed in the brief interval when the box was illuminated on the display.

It is a '97 JGC with the 4.0 (as I previously said) and I have tried to do the key on/off/on/off/on/off/on thing to get the error codes to display on my odometer, but it doesn't display anything, it just sits there. smirking. smirking and pointing at me.

Thoughts?

Thanks!
Paul

[Stud Muffin]

this thread sounds alot like mine.

If it IS the CPS, is there any good reason to get the part from the jeep dealer? I am so used to dealing with my classic cars that mostly don't HAVE dealership parts anymore, that I don't know if these types of sensors are reliable from aftermarket (aka, pep boys, NAPA) or if I need to bite the bullet and get one from the dealership?

[Speck1]

Originally Posted by Stud Muffin

this thread sounds alot like mine.

If it IS the CPS, is there any good reason to get the part from the jeep dealer? I am so used to dealing with my classic cars that mostly don't HAVE dealership parts anymore, that I don't know if these types of sensors are reliable from aftermarket (aka, pep boys, NAPA) or if I need to bite the bullet and get one from the dealership?

Hi Paul! I emailed you the fix for my misfiring on my 1997,2wd,4.0 via private email, but wanted to also list this fix for anyone else out there experiencing this problem of hesitation, stumbling, backfire,dies or almost dies, starts right back up or have to wait a little while, funny carbon burn/gas/exhaust fumes smell senario.
I did two things and of the two don't know which one fixed it. The first thing was to buy a 32 oz. bottle of Marvel Mystery Oil and added 8oz to 10gal of gas, and 16oz. to the oil in the crankcase. Also, the second thing was take ou all the fuses(one at a time) in the engine compartment, and clean off the fuse legs with alcohol and 3m scotchbrite to make them shinny and metallic looking since they looked brown and corroded. After doing that within 3 days of driving now I have not had one missfire or any hesitation. Hope this helps, it sure made a believer out of me after having spent nearly $700 on CPS, Camshaft PS, new distributor, sparkplugs & wires, new fuel pump, screens, and regulator, new catalytic converter, IAC, and new coil---All OEM Mopar parts!!! To be honest, I think the main problem all along was either dirty injectors, or sticking valves, making sense why the Mystery Oil worked to fix it; or a short from time to time in the fusible ignition system since the fuses were corroded and dropped signals to the PCM intermittently. I hope this helps out there, because this problem is a tricky one and very tuff to fix.
Good luck and God bless, Happy Thanksgiving! Speck

[bloodyprice]

ive had the smae problem for a while, the dealer ran a diagnostic and it came up with O2 sesor, so i replaced it and my jeep still dies, so i ran one and the local high school auto shop and that came up with computer chip and ignition coil, i have a brand new ignition coil so i doubt it is tghe problem. but im having a computer shipped to my house right now.

and my engine is to the pont were i ujnplug my O2 sensors and it runs better, but i had no O2 sensors when i bought it to begin with.

[Speck1]

Originally Posted by bloodyprice

ive had the smae problem for a while, the dealer ran a diagnostic and it came up with O2 sesor, so i replaced it and my jeep still dies, so i ran one and the local high school auto shop and that came up with computer chip and ignition coil, i have a brand new ignition coil so i doubt it is tghe problem. but im having a computer shipped to my house right now.

and my engine is to the pont were i ujnplug my O2 sensors and it runs better, but i had no O2 sensors when i bought it to begin with.

Hi! I read your entry--what code was coming up that the dealer put a O2 sensor in? Studmuffin and I were both having a 43 code meaning multiple misfires, and that is the code using our OBD in the Jeep. However, if a 43 code comes up you need to take it to Autozone for a free scan to isolate that code, because within the 43 code are sub/scan codes P0300-P0308; P0300 meaning misfire in all the cylinders, and subsequent codes 301-308 standing for the actual cylinder that alone is misfiring--so P0304 means that cylinder 4 is causing the problem. The problem is either a dirty fuel injector, bad injector, or a sticking valve, usually. Hope this helps! Let me know if the replacement of the PCM fixes your problem. Remember, after installing the new PCM you will need to take it to a dealer to program it to your particular car. Get back to me with your results. Speck

[bloodyprice]

Originally Posted by Speck1

Hi! I read your entry--what code was coming up that the dealer put a O2 sensor in? Studmuffin and I were both having a 43 code meaning multiple misfires, and that is the code using our OBD in the Jeep. However, if a 43 code comes up you need to take it to Autozone for a free scan to isolate that code, because within the 43 code are sub/scan codes P0300-P0308; P0300 meaning misfire in all the cylinders, and subsequent codes 301-308 standing for the actual cylinder that alone is misfiring--so P0304 means that cylinder 4 is causing the problem. The problem is either a dirty fuel injector, bad injector, or a sticking valve, usually. Hope this helps! Let me know if the replacement of the PCM fixes your problem. Remember, after installing the new PCM you will need to take it to a dealer to program it to your particular car. Get back to me with your results. Speck

i work at advance auto parts, thats were i pulled the code from.

I put the 02 sensor in myself.

And usually chrystler pcms program themselves, in my stepdads 97 grand cherokee he replaced the computer and it ran fine after like 2 days of runnin it, his mother and sister works for the local jeep dealership, thats who told us about it.

and ive put fuel injector cleaner in my fuel numerous times, many diffrent types too, so if they work the valves shoule be pretty clean.

i bought this jeep as a POS for $2,500. and it diddnt run after a month.
ive owned it for a year, putting almost $7,000 into it, this pcm will break the $7,000. and i dont mind putting money into it or working on it, cuz i love my jeep, but im sick of ot having an unreliable ride.

hopefully the PCM works.

[Stud Muffin]

Howdy all, back again. Hey Speck1, I appreciate the info in emails and on here. I don't think our problems are exactly the same (for example, you said your car misfired and/or died at speed, but mine only does so at idle, or for a time there, just starting out from the curb or at very low speeds - - also, I have not gotten any codes at all from my JGC - I don't have a reader and cannot seem to make the car cough up the codes using the key on/off thing, and it does not light the Check Engine light), but will try the mystery oil and fuse cleaning, I mean, what can it hurt, right? *L*

This past weekend I replaced the CPS (which took a total of about 20 minutes, thanks to the suggestions and guidelines elsewhere on this site!!!) and it runs MUCH better now. It has only died at idle once, and I no longer seem to get the misfires before it dies (or the one time it died). I still know something else is wrong, but either the CPS replacement, or the resetting of the computer from unhooking the battery, seems to have helped considerably.

Now it still idles roughly when it warms up, or when I am stuck in traffic. At speed it runs like a top, no issues. After about 30 minutes of driving, it also has no problem dropping down to an idle and staying at around 750 on the tach (which is where it typically idles).

I think it may be the IAC yet. I couple weekends ago, I took the NAPA IAC out again and re-adjusted it...but that may have screwed it up more, as I noticed it was positioned outward (the pintel) farther than it was when I initially installed it, and if I adjusted it inward more (back down to 1-1/8 inches) then I fear I may have adjusted it too far in, and the motor is unable to push the pintle out far enough when it needs to. I don't know.

Further, I have been playing around with it at idle a bit, trying to get clues about what is up with it. I have found that sitting there at idle, if I turn the air conditioning off, the engine stumbles and nearly dies, then catches again and idles at 750. If I turn the A/C back on, then the idle speeds up (as it should) and then settles down again to around 750. I can reproduce this effect at will simply by turning the A/C on and off.

It really seems to me that the IAC is just not responding FAST enough sometimes. Now I wonder if the times it has died recently in traffic at idle, if the A/C just happened to cycle off at that moment? Hmmmm....hard to catch that one. But whatever the issue is, it seems to be directly affected by turning my A/C on and off (turning the power steering left or right does not seem to have an effect).

To me this issue and the A/C thing points at the IAC. So, probably this weekend (unless anyone else shows me the error of my ways before then) I will get a new IAC from the dealer and see where that gets me.

[Stud Muffin]

Well, Speckster...now I'm with you.

For the first time since this started happening, I was finally able to go freeway speeds the whole way to work (hey, it is the 405 corridor in LA!), and actually finally had it cut out on me at about 70 MPH!!! WTF???

Still at about the same time period into the drive (around 30 minutes or so) from where I got on the road this morning. Probably my imagination, but it seems more time-related than anything at this point *LOL*

After I flipped into Neutral and restarted it, it continued on the way just fine the rest of the trip to work (another 20 minutes or so). Once to work, I idled a while in the parking lot, and it would run fine, then stumble, then run fine, then race a bit, then run fine.

...as I listened to this, I could hear the A/C cycling on and off also. So at least THAT part (the intermittent stumbling at idle) is very definately related to the A/C coming on and off. THAT must be the IAC, I would think (other thoughts welcomed, however!).

Still cannot figure why the IAC would have anything to do with causing the engine to die at 70 MPH though...so probably I am dealing with two different issues.?!?!?

I put the MMO in last night. Will try to clean the fuses this weekend. Sure would like to fix this without throwing $700 worth of parts at the bugger.

[Speck1]

Originally Posted by Stud Muffin

Well, Speckster...now I'm with you.

For the first time since this started happening, I was finally able to go freeway speeds the whole way to work (hey, it is the 405 corridor in LA!), and actually finally had it cut out on me at about 70 MPH!!! WTF???

Still at about the same time period into the drive (around 30 minutes or so) from where I got on the road this morning. Probably my imagination, but it seems more time-related than anything at this point *LOL*

After I flipped into Neutral and restarted it, it continued on the way just fine the rest of the trip to work (another 20 minutes or so). Once to work, I idled a while in the parking lot, and it would run fine, then stumble, then run fine, then race a bit, then run fine.

...as I listened to this, I could hear the A/C cycling on and off also. So at least THAT part (the intermittent stumbling at idle) is very definately related to the A/C coming on and off. THAT must be the IAC, I would think (other thoughts welcomed, however!).

Still cannot figure why the IAC would have anything to do with causing the engine to die at 70 MPH though...so probably I am dealing with two different issues.?!?!?

I put the MMO in last night. Will try to clean the fuses this weekend. Sure would like to fix this without throwing $700 worth of parts at the bugger.

Hi Muffinator! I,m not glad you had to experience this cutout and dieseling at 70mph, but it sure does point to the fact that we have very similar issues. Yes, I have had issues at "idle", like you described, I've had issues at just about every speed without warning--it just starts misfiring, stumbling, and dieseling wanting to die out and then just picks up and runs like a champ! Or, it may die out, but will restart right away, maybe stumble again, then run fine the rest of the trip. Whenever it starts this weird action, I know it well and can anticipate it, I usually put it in neutral and push several quick times on the acclerator and it usually picks up and runs fine.
The one thing I can state for sure, is that it does not ever, ever happen until I have been driving for between 15-30 minutes. So, I keep thinking what can take sooooo looong to warm up?
After writing you last time about the MMO, and cleaning the fuses, I have not had one problem------until today! Ugh! But I was pulling my 18 foot center counsel offshore fishing boat uphill at about 50mph and it misfired a couple of times---but did not die out! So, I continue to add MMO to my gas hoping that maybe there is still some carbon on my valves?
Being that we live in somewhat similar climates, I live in Daytona Beach,FL area, maybe heat is a common denominator. Whatever, I am groping somewhat because this problem is actually getting to me now. My wife says to trade it in, but it looks like new and has been probably the most reliable vehicle we have owned! It has 235K on it and really does drive nicely. They wouldn't give me much on a trade---that's why if I can solve this one problem--I'm home free for a long time to come.
Let me ask you---have you replaced the PCM yet? I have been talking to others on the net and can't remember if you have done that. It seems like most all those that have--- resulted in a no/fix situation, or a worse problem at best.
The only thing that bugs me is that you are not able to pull up a trouble code on your onboard diagnostics!!! By turning the key on and off three times quickly and then the 4th time just turn it on (not start) and leave it there it should cycle a 12, then some code, and end with 55. Mine always comes up with a 43 code--multiple misfires. The check engine light does not come on, but after an experience with a bad stumble/dieseling/dying-- when I get to my destination, I will turn the car off and do this on/off thing to pull up this same code everytime. I disconnect the battery to cancel the code from memory so it just shows a 12, then 55 and know the code is not there, and it stays gone until I have another prob. I took it to Autozone after an episode with the 43 code in there and they scanned a PO351 code which states a problem in the primary or secondary ignition system. Well, I have replaced (2 times now) everything in these systems. So, I am really "lost"---maybe I should sign on to the TV series and join everybody else on that island--because I would fit right in! Ha!
Anyone else out there that could be of any assistance would be greatly appreciated!!!!!! Would really hate to give in to my wife's idea to trade--it sounds like a macho thing, but not really--just want my Jeep back to 100%. If anyone out there has found a "true fix for good", please, please take a minute and say hello. Thanks, Speck--getting desperate!!