ZJ: URGENT! My ZJ died suddenly! Help!

[TOOLman]

My ZJ has been running badly for awhile. I've suspected electrical problems, although the Jeep service shop thought it was weak valve springs.

This afternoon, she started without any problems. She was running a bit uneven, but not as bad as it has been the last week. Then I stopped to do some shopping on my way home. I came out, unlocked the Jeep with the remote, and turned the ignition key. Nothing!

It is completely dead. No warning lights go on, the "ping ping" sound that indicates that the door is open isn't heard. No reaction from the engine. All that is heard is a loud ticking noise that sounds like it's coming from the glove compartment. If I open a door, or the glove compartment, the ticking stops.

I can't see any problems under the hood. The voltage gauge was reading normal before I switched the engine off.

This is a disaster for me. I live far from everything, i.e. no public transportation. Fortunately a couple of neighbors showed up at the store, and gave me a lift home. I'm supposed to be in another town next week for a job. I need my Jeep!

Please, if anyone knows what could be the problem, let me know ASAP. If you don't already, please think of me as an ignorant fool, and explain everything thoroughly.

I'm seriously thinking of getting rid of my ZJ right now :(

TiA

[Howler]

Sorry to hear that Tommy. First thing that comes to mind is the Battery. Someone correct me if I am wrong but I think th voltage meter measures the voltage of the altinator. So if the Jeep is running and the altinator is putting out the right volts it would read ok. The other reason I think it is the battery is because you said that there was no door chime, no turning of the starter and you have been having electrical problems. Did you not say you needed a new battery before? Hope this help. Only other thing is I will keep my fingers crossed for you.
Howler

['76CJ5]

May be a bad battery or a bad connection to the battery and since there was no charge going to the battery it's not charged up enough to start the jeep. Take calble off and clean terminals then charge it back up.

It's the cheapest thing to do anyway

[TOOLman]

I bought a new battery today ($100 :() and my ZJ came back from the dead. Unfortunately, it still isn't well.

At first, the engine ran very roughly, barely managing to idle. At higher RPMs, the whole engine shook. After 15-20 minutes idling, it stabilized somewhat. When I put it in gear and drove away, it didn't feel good at all. After a restart, it was OK for awhile, but then the old problems came back again (misfiring, shuddering).

I have got many tips from people on what could be the cause: battery leads, ignition wires, cap & rotor, coil, TPS, CPS, valve springs, bad ground, ... I just don't know anymore. Where do I start looking? I don't want to spend $75 on ignition wires or $60 on a new coil if I don't have to.

Howler and '76CJ5 - you were both dead on about the battery. Thanks a lot, guys!

[Howler]

Tommy it is nice to see that you have played god(notice the small g) and have risen you ZJ from the dead. Do you have the haynes manuel?

[TOOLman]

Yeah, that should be a very small 'q' :rolleyes:

No, I don't have the Haynes manual. I've been thinking about getting that or the FSM, but I haven't gotten around to it :( To make things worse, even my owner's manual is virtually useless, since it's in German.

[Howler]

Thats ok I have it right here. It says it could be the following
1) Vacume leakage. Check mounting bolts/nuts at the throttle body and intake manifold for tightness. Make sure all vacume hoses are connected and in good condition. Use a stethoschope or a lenth of ruel hose held against your ear to listen for a vacumm leaks while the engin is running. A hissing sound will be heard. A soapy water solution will also detect leaks.
2) Fuel ingection system check
Chelk all ground wires connections on the intake manifold for tightness. Check all wiring harness connectors tthat are related to the system. Loose connectors and poor grounds can cause many problems that resemble more serious malfunctions. Check air intake duct to make sure no leaks. This can cause a to lean fuel mxture. Check all vaccum hoses contected to the intake manifold.
3) leaking head gasket.

Thes are all the ones that seem to pertain to your problems. Did this happpen after the kolak exhust install? I am giong home soon but I will stay on for a little to see if this helps.
Howler

[MaineZJ]

Tommy, I'm sorry you are having so much trouble. I'm not a mech, but I do have a Haynes manual. If ya need something out of it, I can always scan it for you. Good luck man.

[TOOLman]

Thank you, guys!

Howler - yes, this happened some time after the Kolak exhaust install, but I don't think it is related. I did most of the things you listed. I've re-tightened the bolts holding the intake manifold and headers several times, and checked on all the bolts, screws, electrical connectors and vacuum hoses we tampered with during the installation.

I haven't been able to locate any ground straps yet. The entire engine bay is in dire need of a good cleaning, and I think I'd need a hoist to be able to check things properly from underneath. It's difficult lying on your back on the garage floor, with insufficient lighting.

I hope it's not the head gasket (sounds very expensive). I'm fairly convinced that it's electrical. I'm going to try new ignition wires. My brother had very similar symptoms a few years back on a Saab 900 Turbo, which was remedied by new ignition wires. The OEM ones are too expensive, so I'm going to go with a brand that some guys I know sell (they have an engine reconditioning company).

I went for a ride today, to see how my ZJ would behave. On the way into town, it was running badly. Then I stopped for a burger, and after that she ran very well for awhile. Another stop (for cat food), and she started missing again. For awhile it was quite bad.

Since the problems come and go, I think it's more likely to be electrical than caused by bad gaskets or valve springs or such like. I'll try new ignition wires and keep my fingers crossed...

Thanks again for your help. I'm going to try to get that Haynes manual soon.

/Tommy

[Lou Corrado]

Tommy,
Sorry to hear of your troubles with the ZJ, most people who have had Chry Co products know thay sometimes do have electrical problems. The things I would look at (you have to get a digital multimeter):
Spark plug wire resistance
Coil resistance, secondary and primary (check
cold and hot, to see if it breaks down under heat)
Batt cables
Ground connections
Ssice you recently installed a header, make sure you don't have an intake gasket vacuum leak--If you spray some oil around the gasket with it running, and it gets sucked in that could be it.
The things that can change cold/hot--coil, intake man gasket (expansion/contraction) are suspects.
If you notice a change in damp weather--poor grounds are suspect.

Good Luck, it must be frustrating getting a US vehicle fixed in Sweden, it's hard enough here!!

Lou C

[TOOLman]

Thanks, Lou.

I've checked for leaks all around the new intake and exhaust, but can't find any. Everything has been re-tightened and checked several times, even the O2 sensor. All vacuum hoses seem fine, and I've tried the method you describe to detect leakage. The manifold gasket was replaced when I installed the headers, so it should be fine. No hissing noises are heard, either.

Recently it has been running badly both when cold and when hot. Sometimes it can run fine for awhile, even when hot, then start missing again.

Tomorrow night I'm going to replace the spark plug wires, just in case. If that doesn't help, I'll have to check out the coil. I've got the resistance numbers you posted before. All I need to figure out is where to attach the multimeter :)

Moparman suggested it could be a bad TPS or CPS, but I don't know how to check those myself. The problem is that no shops around here seem very capable of handling these kinds of problems. They can do a normal service, or replace an obviously failing part, but not much else. Thank God for the Internet, and for all you guys, I say!

[MaineZJ]

Tommy, if ya unplug the TPS sensor you should get a resistance reading that increases smoothly as you open and close the butterfly valve on the throttle body. I think the connector has three contacts so you should be able to figure out which two to take the reading from. I seem to remember doing this check. HTH. And if I'm wrong I hope someone chimes in.I couldn't find it in my Haynes (just did a cursory check). Good luck.

[TOOLman]

Thanks!
Since I don't have a manual, can you give me a pointer to where the TPS sensor is located? I guess it's on the throttle body, but there are quite a few connectors up there...

[MaineZJ]

Tommy, e-mail me at my hotmail account and I will reply with page out of my Haynes. It will be an attachment with pics: osiyeza@hotmail.com

[MaineZJ]

Maybe this will work,Nope, tried to attach file here, but it's to big.

[MaineZJ]

From Haynes:"The Throttle position sensor is located on the end of the throttle shaft on the throttle body. By monitoring the output voltage from the TPS, the PCM can determine fuel delivery based on throttle valve angle(driver demand). A broken or loose TPS can cause intermittent bursts of fuel from the injector and an unstable idle because the PCM thinks the throttle is moving"
To check: "Locate the TPS. Using a voltmeter, check the reference voltage from the PCM. Install positive probe (+) onto the purple/white wire and neg. probe (-) onto the black/blue wire. " Tommy, make sure you have the connector removed and your key on) "The voltage should read approx. 5.0 volts DC."
"Next connect the connector back to the TPS and check the TPS signal voltage. With the throttle fully closed, connect the positive probe of the voltmeter onto the orange/blue wire and neg. probe to ground. " Tommy, you'll probably need sharp thin probes for this. "Gradually open the throttle valve and observe the TPS sensor voltage. With the throttle fully closed, the voltage should read approx. .5 Volts. Slowly move the throttle valve and observe a distinct change in the voltagevalues as the sensor travels from idle to full throttle." Tommy this voltage should rise smoothly. "The voltage should rise to appox. 3.5 to 5.0 volts. " If not Tommy, you may try cleaning it or replacing it. HTH!

[MaineZJ]

And if you want to know how to check you MAP sensor, let me know. It might be worth checking also.

[TOOLman]

Thanks!

I'll see if I'm able to do this tonight. Since I travelling a bit further than usual this week (working in another town), and going long distances through unpopulated areas with no cell phone coverage, I'm thinking about switching cars with my brother. His old Audi may be rickety, but at least it runs.

It turned out I couldn't get any new ignition wires from those guys after all. I would really like to know if that's the problem before spending $75 on a new set.

[MaineZJ]

Tommy, have you done the night-time check of your spark plug wires? I don't know how old yours are, but I think if you open the hood, start your engine in the dark, you can see spark to ground or something like that if the wires are cracked/insulation gone. But it's gotta be totally dark so remove your hood lamp.

[MaineZJ]

Tommy, if your CPS is gone, the engine won't run at all. I don't know for sure if they can gradually go bad on you, but I do know it's located on your transmission bellhousing and if loose, it too may cause you problems. The check is pretty simple. Pins B and C of the connector should show an infinite reading with an ohm meter. The replacement is a little bit tricky though.

[TOOLman]

I did the night time check - no sparks. That doesn't mean the wires are OK, though. My hood lamp doesn't work (I think I lost the little mercury switch at one time), but I still had to wait until the middle of the night, since it doesn't get very dark up here this time of year...

It now runs roughly even when cold. Then it can be OK for awhile, and a few miles later it's missing and jerking enough to give me a whiplash injury. I doubt that it's the coil or the ignition wires. The TPS is maybe the safest bet right now.

I switched cars with my brother last night (he only has 7 miles of highway driving to work, so he's not as vulnerable to failure as I am). He's going to take it to some friends of ours, who run an engine reconditioning company, and see if they can figure out what's wrong. If they don't, I'll try testing the TPS as you described.

It was Moparman (on JU) who suggested that it could be TPS or CPS. I don't know enough about Chry Co engines to see what's possible or not.

[Jerry Falletta]

Tommy,

Your CPS could be failing, but not totally dead (yet). The CPS on mine did that (before I owned the Jeep); the dealer changed a lot of stuff before guessing :rolleyes: at the CPS. All was under warranty, but left the original owner with little faith in that dealer's service department.

Also, if the spark plug wires are bad, they may not emit sparks (as seen in darkness).

The valve spring problem was for misfire on the I-6 engines that usually had 30-40 thousand miles on them (mine had 60,000 on it when it needed new ones). This misfire would occur under load, such as pulling up a long hill at about 3,000 RPM.

Let us know how it goes.

Jerry

[TOOLman]

Thanks, Jerry.

As I said in my reply to MaineZJ's suggestions, I'm aware of the fact that the absence of sparks doesn't mean that the wires are OK. However, in my limited experience, bad spark plug wires usually lead to misfire during load - the more load, the more misfire. That is not the case here.

In fact, lately the most troubles have occurred when driving in O/D at 55-70 mph on fairly flat ground (1500-2000 RPM), with little or no load. In inclines, when the load increases, the problems usually go away or at least are less severe.

Sometimes the problems get worse, even occurring at 30 mph. When that happens, it's not so much a question of obvious misfires (jolts), but more of wildly varying RPM. I can keep the accelerator perfectly still, and the engine can vary +/- 500 RPM in alternating directions. People hearing this must think I'm on drugs or something, because it sounds as if I'm constantly stepping on the pedal and letting it go. Does this sound like a faulty TPS?

My ZJ has about 80,000 miles on the odometer. Since I bought it (a little over a year ago) I've driven it about 30,000 miles. I have no idea what repairs, if any, the previous owner has done. I guess I should be able to find that out using the VIN number, but I'm not sure if it would help.

I have also noticed a lot of soot at the end of the tailpipe. To me, that indicates that the fuel isn't burning as it should. My mileage is also lower than I expected, even with the 31's. I'm usually somewhere around 15-17 mpg, but with the kind of driving I do, I'd expect more like 18-20 mpg.

[Howler]

Hey Tommy sorry to hear you are still having problems. Ok first thing. Your engine ground wire is located at the back of the engine. Mine allthough a V8 is located on the driverside/back of the engine. It is green in color( Copper green) and it looks more like a strap then a wire. I have two straps and they ar bolted right below the Cowel.
As for the engine trouble. This might be a long shot but I went back and read your original post and this TSB 18-48-98 comes to mind. Here are the symptoms:
* Spark knock complaints with behicle under load
* Various single cylinder misfire(1,3,7) ad especially 5 and/or 8
* Surge in 4th gear with the Electronically Modulated Converter Clutch(EMCC) engaged (around 45 MPH)
* Perceived torque converter EMCC engagement/disengagement around 45MPH.
If this sound close here is the link. Unfortunatly I am unable to access the page but I am supplying the V8 link. There is a link at the top of the page for the I6. Let me know if it does not work.
http://dodgeram.org
Howler
EDIT: New link. Page moved

[TOOLman]

Howler - that seems to pertain to the 3.9L V6, not the 4.0L I6. Or did I look at the wrong place?

The symptoms described do not match very closely what I'm experiencing. My engine sometimes runs "uneven" when cold (RPM's varying although accelerator is kept still). At those times it even has problems at idle.

Mostly, though, the problems occur with a warm engine at 50-70 mph with the tranny in overdrive (1500-2000 RPM). With little or no load on the engine, it feels like the entire ignition is switched off for an instance, causing a severe jolt. It's only for a fraction of a second, sometimes barely noticeable, at other times enough to cause whiplash.

My friends at the engine reconditioning company tested it yesterday, but could only provoke this behavior at maximum acceleration at WOT. They recommended changing the fuel filter, just in case. They ordered one, which will come in today or tomorrow.

I don't feel convinced that this is the problem, though. They also recommended that I change cap, rotor, and spark plug wires, to be on the safe side. The thing is, the wires are quite expensive, and I'd rather not change them unless I have to.

As soon as I get my Jeep back, I'm going to try to test the TPS like MaineZJ suggested. If nothing else helps, I'll have to find a shop where they can plug in the diagnostic tool and see what it says.

[satan]

You mentioned that this vehicle was running rough for a while before this all happened...

... and I didn't see this in the balance of this thread, so:

Did you check your sparkplugs for fouling and/or the rest of the secondary ignition system for corrosion/wear -- the ECU on your vehicle controls spark voltage and would try to reduce the voltage to minimum values under low-load steady-state driving conditions EXACTLY as you mentioned...

Now, if your vehicle had a corroded batery terminal, and replacing the battery fixed that problem, it's quite likely that you have one (or more) fouled plugs (reduced available spark and all sorts of low-current false ECU readings).

The plugs would fire 'kinda-OK' when the ECU deliver's full spark (cold starting), and would fire worsen as the cylinders they're in load up as you drive and (as mentioned) probably miss all together as the spark voltage is reduced at cruise (further exacerbating the fouling).

Ususally a change of plugs and a good fuel-injector cleaning will restore these types of issues (providing that the rest of the electrical porblems have been resolved...

[TOOLman]

Yes, I have checked up on the plugs. It was mentioned in an earlier thread on the same issue, but not in this one.

When these problems first started, my #1 action was to replace the plugs. That solved the problem, for two weeks. The old plugs looked just fine. I replaced them with Beru 4-electrode plugs that have worked very well in the past.

My Jeep is still at my brother's. Yesterday was a Christian holiday here in Sweden, and today I'm working from home, so he'll have it until tomorrow (he says he can definitely live with driving my Jeep for a few days...). The strange thing is that it seems to be fine now. He didn't notice any jolts at all on Wednesday (didn't talk to him yesterday).

I guess I'll have to wait and see if the problems return :rolleyes:...

[Howler]

Well Tommy, I haven't found anything else for you but I' keep this in mind when ever I see any technical stuff. You know you might have a problem getting your Jeep back now if your brother can stand driving it ;). Anyway best of luck.
Howler

[MaineZJ]

Tommy, I'm just wondering how your ZJ is doing. Anyway I came across this over at JU, sound familiar?
"Please help diagnose my ZJ symptoms"
That's the subject of the post on the ZJ board, Jerry may be right about that CPS or you may have a combo of probs. Hope you find out and get your baby running right soon. Oh here's the link.
http://forums.jeepsunlimited.com/ubb/Forum22/HTML/004809.html

[TOOLman]

It still sucks :(
I saw that thread on JU, too. The symptoms appear to be quite similar, although I interpreted 'lurch' as a forward jolt, while I'm experiencing backward jolts (i.e. temporary loss of speed).

This morning it was ridiculously cold (29°F!), and my ZJ ran fairly well. Maybe it prefers cool weather?!

I'm going to replace the fuel filter, and see if that helps. If not, the ignition wires are next. Failing that, she's bound for the dealer's... :( (I have yet to try to measure the TPS according to your instructions. Maybe tomorrow.)

Thanks for caring, and for your help.
/Tommy

[Jeepiter]

I'm no mechanic but if your battery died and after new replacement your idle/cruise is rough your system is not charging right or at all. Bad plugs, wires etc, it's all nice but your battery would not have gone bad from it, and all things being equal swapping in a new one would not raise the ZJ from the dead. Either charging system is defective or you've got a short somewhere.

[TOOLman]

I understand what you're saying, but I don't think that's the problem. Old batteries can die suddenly even though there is nothing wrong with the charging system. If inadequately maintained, there will be lots of gooey stuff floating around in the battery acid (oxide and lead particle fallout due to electrolytic processes). If there's enough of this, it could short out a cell by causing a galvanic contact between the lead plates, and the battery is dead. I tested the acid a few weeks prior to the incident, and discovered that it was in a bad condition. I didn't think it was that urgent to replace it, though, so I guess I waited too long...

If the charging didn't work, I'd have drained the new battery by now. There is also a green LED on the new battery, indicating its condition, and it's lit up as it's supposed to be.

The last few days my Jeep has been running a little better, although far from good. Last weekend I put some STP injection cleaner in the tank, but I don't know if that's what made a difference. I'm beginning to think that it is the TPS after all, because I've noted that the jolts occur more frequently with the accelerator in a certain position. I haven't had time to do anything about it this week, but it's supposed to be cold and rainy this weekend, so I might have some time to look at it.