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Unread 07-30-2013, 12:28 PM   #106
UDY925
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1998 ZJ 
 
Join Date: Jul 2013
Location: Sevenoaks, Kent, England
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I just had to say a big thank you for this thread. I found this forum purely by chance when surfing, looking for a transmission pan drain plug kit (don't seem to be available over here). I've been experiencing intermittant stall problems on my '98 GC for some time - usually when I take my foot off the gas going around a corner and just when I need the PS to be working . I'm sure the "dirty dozen" will help resolve the issue.

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Unread 08-02-2013, 12:53 PM   #107
ZeeJay1997
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Need some input

Ground locations specified are for 96-98 with 4.0 engine. If you have accurate location information for earlier models / different engines, please let me know and I will make edits to include. I know the 93 4.0 PCM ground is at the battery terminal. Please help me make a list so i dont confuse people.
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Unread 09-04-2013, 02:30 PM   #108
cgcarpenter
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Before I bite the. Bullet and buy my second PCM in two years I want some input. I'm stalling/hesitating/backfiring.
Stalling under no load.
His situating under slight load.
And heavy load like on the free way it'll usually back fire 1 or two times and be fine.
I had a P0351 so I tested my old coil and replaced cuz the resistance was too low. With a coil that tested well. It even ran better with it.
And a week ago I got p0108 saying map sensor voltage was too high. Got that code once never again. And it was way worse that day.
When it starts acting up I can always smell unburned gas afterwards.
It seems to happen worse when it's really hot like above 90 or pretty cold like below 70.
And it ALWAYS starts back up and runs fine after its little fit. Unless it sits for 3-4 hours.
I've done almost all the dirty dozen except fuel pressure.
Cap plugs rotor coil battery have been replace in last 6 months.
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Unread 09-04-2013, 03:25 PM   #109
Oldfrog
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I've had the same thing this summer. I tested my battery and even though it's only a few months old, I think it's crapped out. My charging system is only at 13.6 at idle and the battery ( engine off) is about 12.4 or so. I'm beginning to think these new batteries arent worth a dime. Might need yet another PCM, but I'm checking each and every system and connection before I go that route again. No happy with the battery voltage at all. And yes all my grounds are shiny and tight. Yesterday it stalled and wouldnt start, so on a hunch, I pulled the TPS connector plug and then plugged it back in. It started fine. ( new tps too). Had tested the 5 volts at the TPS a day earlier and it was fine. If it stalls today, I'll test for 5 volts again before I re-start it.
I thought I had this thing licked earlier this year, but it seems to have come back. New NTK o2 sensors too. Might be the Mopar crank sensor again, so I'll test it again when it stalls. For now...I'm still leaning towards the funky batteries, which cause the PCM to act stupid. A fully charged battery needs to be at 12.6 volts. ( 2.1 volts per cell)
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Unread 09-04-2013, 06:06 PM   #110
cgcarpenter
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Quote:
Originally Posted by Oldfrog
I've had the same thing this summer. I tested my battery and even though it's only a few months old, I think it's crapped out. My charging system is only at 13.6 at idle and the battery ( engine off) is about 12.4 or so. I'm beginning to think these new batteries arent worth a dime. Might need yet another PCM, but I'm checking each and every system and connection before I go that route again. No happy with the battery voltage at all. And yes all my grounds are shiny and tight. Yesterday it stalled and wouldnt start, so on a hunch, I pulled the TPS connector plug and then plugged it back in. It started fine. ( new tps too). Had tested the 5 volts at the TPS a day earlier and it was fine. If it stalls today, I'll test for 5 volts again before I re-start it.
I thought I had this thing licked earlier this year, but it seems to have come back. New NTK o2 sensors too. Might be the Mopar crank sensor again, so I'll test it again when it stalls. For now...I'm still leaning towards the funky batteries, which cause the PCM to act stupid. A fully charged battery needs to be at 12.6 volts. ( 2.1 volts per cell)
Have you by chance replaced you relays? I'm going to check mine tomorrow because I recently had my transmission one go bad and I read about somebody saying one of yhe relay was intermitent and caused these problems.
I've already gone trough the secondary ignition so I figure I might as well go through the primary/low voltage side next. Just my two cents. Quick check couldn't harm anything.
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Unread 09-04-2013, 06:33 PM   #111
ZeeJay1997
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Quote:
Originally Posted by cgcarpenter View Post
Before I bite the. Bullet and buy my second PCM in two years I want some input.
Did the symptoms go away after the first PCM? Are the symptoms you are having now the same as the first PCM?

Have checked for spread contacts on the coil connector?
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Unread 09-04-2013, 06:50 PM   #112
ZeeJay1997
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Quote:
Originally Posted by Oldfrog View Post
I pulled the TPS connector plug and then plugged it back in. It started fine. ( new tps too). Had tested the 5 volts at the TPS a day earlier and it was fine. If it stalls today, I'll test for 5 volts again before I re-start it.
I think you're hot on the trail like a coon dawg in the swamp. It could be something else involved in the circuit besides the TPS. Maybe something pulling down your sensor ground.
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Unread 09-04-2013, 08:13 PM   #113
cgcarpenter
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Quote:
Originally Posted by ZeeJay1997

Did the symptoms go away after the first PCM? Are the symptoms you are having now the same as the first PCM?

Have checked for spread contacts on the coil connector?
Similar but not the same. That's why I haven't gotten a new one yet.
Before it would completely cut out and I'd have to wait 10-15 minutes to start. And no check engine light. And didn't back fire usually just cut strait out enough to know exactly what time and where to pull over when it was going to lol

This time i got codes and no wait time.
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Unread 09-04-2013, 08:35 PM   #114
ZeeJay1997
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Quote:
Originally Posted by cgcarpenter View Post
His situating under slight load.
'splain this to me
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Unread 09-04-2013, 09:21 PM   #115
cgcarpenter
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Quote:
Originally Posted by ZeeJay1997

'splain this to me
Hesitating lol
Like drop rpm bounce stall or go back to normal you can never guess which
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Unread 09-05-2013, 03:10 AM   #116
Oldfrog
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Quote:
Originally Posted by ZeeJay1997 View Post
I think you're hot on the trail like a coon dawg in the swamp. It could be something else involved in the circuit besides the TPS. Maybe something pulling down your sensor ground.
Not sure, my friend. I'm digesting the following info tonight:

New symptom today after it warmed up. ( it's always after it warms up thoroughly, btw). Today, instead of the PCM trying to time the spark properly ( that's what it sounds like....a really retarded timing)....it started running fine....except it wouldnt rev...and sounded like it was hitting on maybe 3 cyls.
Wow..that's a new one ! I was sitting in the bank parking lot when it happened. I kill it, hop out with my voltmeter, turn the key back on and get 5.1 volts on outer two pins of the tps connector...which I unplugged. Hmm. Now it starts back up and runs normally. I have another new TPS still in the box....going to try that tomorrow, just in case this one is out of spec.

It was HOT outside today ....and I know it's heat related. Bought another new PCM today, ( going to warranty the old one) but havent installed it. Tonight, I drive home at O300 and it's cool outside. Engine is at operating temp for about 12 miles. Stopped for a coke and let it heat soak for 10 min. Started right up and 1 mile later, it "bumps" once. Another mile ( both at about 1400 rpms) another miss. If I had kept driving, it would have eventually gone into "stupid mode"...seeking the correct timing or injector firing sequence ( whatever the heck it's doing) ....etc...but I was home.

Tomorrow ( today)...I'll check the cps. But I'm still not happy with that battery voltage and dont want to install the new PCM until I get that particular issue sorted out in my head. If I have to park this sucker and rewire the entire engine/tranny harness over the next month, I will do just that, in order to defeat it once and for all.

I still cant help but feel like I'm missing something. Battery temp sensor? Valve cover leak messing with the cps ? BTW, fuel pressure is a steady 46 and didnt leak down at all for 3 min...so I think it's fine.

Ideas, Zeejay?
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Words of wisdom, Posted by Zeejay:
"..it's not air, it is the opposite of air... suckage so to speak."

Stalling? Work through Zeejay's list
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Unread 09-05-2013, 05:26 AM   #117
Uniblurb
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Quote:
Originally Posted by Oldfrog View Post
New symptom today after it warmed up. ( it's always after it warms up thoroughly, btw). Today, instead of the PCM trying to time the spark properly ( that's what it sounds like....a really retarded timing)....it started running fine....except it wouldnt rev...and sounded like it was hitting on maybe 3 cyls.
Wow..that's a new one ! I was sitting in the bank parking lot when it happened. I kill it, hop out with my voltmeter, turn the key back on and get 5.1 volts on outer two pins of the tps connector...which I unplugged. Hmm. Now it starts back up and runs normally. I have another new TPS still in the box....going to try that tomorrow, just in case this one is out of spec.

It was HOT outside today ....and I know it's heat related. Bought another new PCM today, ( going to warranty the old one) but havent installed it. Tonight, I drive home at O300 and it's cool outside. Engine is at operating temp for about 12 miles. Stopped for a coke and let it heat soak for 10 min. Started right up and 1 mile later, it "bumps" once. Another mile ( both at about 1400 rpms) another miss. If I had kept driving, it would have eventually gone into "stupid mode"...seeking the correct timing or injector firing sequence ( whatever the heck it's doing) ....etc...but I was home.

Tomorrow ( today)...I'll check the cps. But I'm still not happy with that battery voltage and dont want to install the new PCM until I get that particular issue sorted out in my head. If I have to park this sucker and rewire the entire engine/tranny harness over the next month, I will do just that, in order to defeat it once and for all.

I still cant help but feel like I'm missing something. Battery temp sensor? Valve cover leak messing with the cps ? BTW, fuel pressure is a steady 46 and didnt leak down at all for 3 min...so I think it's fine.
Oldfrog, I'm sure you know more than I do and I sure don't have the wealth of info in my head like ZeeJay does. But I'll give my 2 cents worth on your problems which sound similar to the ones I was having.

After going through 2 PCM's ( on the 3rd), and 4-5 crank sensors (shouldn't even count the 2 aftermarket ones), I took cleaning my engine grounds a step further. I removed the coil bracket and couldn't believe how much oil/corrosion was on the backside and studs. As you know the PCM is grounded to one of these studs which in turn grounds all sensors. I cleaned everything up including removing the studs and cleaned out the holes in the block themselves with a worn battery terminal cleaner brush. Believe this did help some.

I also wondered about my charging system and removed the alternator and the bracket from the block. Again, could not believe how much corrosion/oxidization was on the bracket where it meets the block. And where it wasn't corroded the aluminum was glazed over. As you know aluminum does not like steel and cleaned all this off. While maybe not necessary I ran a new ground wire from one of the bottom/back bolts on the alternator to one of the clean coil studs.

Also since one of the small contacts on middle of the alternator, believe it's the green wire, communicates with the PCM on when to kick the charging field on, I cleaned these contacts off real good too.

On my last bad Mopar crank sensor it would fail mainly due to heat. Once the engine became hot it would start sputtering, coughing and finally die. I've also wondered if oil coating the CKP would cause problems but have been told by several reliable sources the signal will go right through a coating of oil. Still believe I'd test your CKP using the procedure/link in my signature.

Good luck and hope you figure it out!
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-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
-Crankshaft position sensor multimeter test. & video of testing.
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Unread 09-05-2013, 02:46 PM   #118
Oldfrog
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Thanks, Uni.
I have removed the coil bracket and cleaned it up. The alternator bracket....no...havent tried that. Dont have time to mess with it today and I have to drive across town. ( it might force me to TAKE time with it, though..) Stopping by the stealership and getting a new CPS just in case. I have the original Mopar in the cargo area as well as the one in the bellhousing. One more wont hurt and I may need it before my day is over.

I'm NOT installing the new PCM today, until I check the CPS and install a new IAC..just for grins. With me, it isnt about the money so much as the inconvenience of it all. My plate is already full enough as it is, as evidenced by my 4 AM or 4 PM posts.

I still dont like my battery voltage one bit.
__________________
Cajun Recipes and Fishing tips

Words of wisdom, Posted by Zeejay:
"..it's not air, it is the opposite of air... suckage so to speak."

Stalling? Work through Zeejay's list
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Unread 09-05-2013, 07:45 PM   #119
cgcarpenter
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Quote:
Originally Posted by Oldfrog
Thanks, Uni.
I have removed the coil bracket and cleaned it up. The alternator bracket....no...havent tried that. Dont have time to mess with it today and I have to drive across town. ( it might force me to TAKE time with it, though..) Stopping by the stealership and getting a new CPS just in case. I have the original Mopar in the cargo area as well as the one in the bellhousing. One more wont hurt and I may need it before my day is over.

I'm NOT installing the new PCM today, until I check the CPS and install a new IAC..just for grins. With me, it isnt about the money so much as the inconvenience of it all. My plate is already full enough as it is, as evidenced by my 4 AM or 4 PM posts.

I still dont like my battery voltage one bit.
Yeah my voltage doesn't seem right. What should it drop to when cranking? Mine Is sinking to about 9-10 volts sometimes lower.
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Unread 09-05-2013, 08:09 PM   #120
ZeeJay1997
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Quote:
Originally Posted by cgcarpenter View Post
Hesitating lol
Like drop rpm bounce stall or go back to normal you can never guess which
Have you zip tied the connectors yet?
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