XJ 1998 VM 2.5 turbo diesel - limp mode?
 

Hi
I've recently acquired an XJ 1998 VM for my son (he's on learner's, and I have a ZJ 98 4l petrol)
Car was reasonably priced (2k unregistered at 137000km)
However, got some weird problem, and I'd appreciate some advice (I've been lurking here for a while and can't figure it out)
Car runs nice, no smoke beyond first second when starting.
Revs to redzone and has a lot of pull in 1st and 2nd gear (AX-15 I believe).
If I go uphill in 3rd or 4th, would barely make it to 2100 rpm max
Checked #1, it's around 100ohms.
Dropped 100ml acetone in the tank, did some 100km ( short 4-20 km trips) seems marginally better.
Ran some liquimolly diesel cleaner through the throttle body...
Little improvement (maybe placebo)
When I accelerate in first, second, and even third (if not uphil), throttle pedal is very sensitive (sometimes jerks if I'm not operating the pedal very finely).
In 3rd or 4th, seems to loose any effect after depressing the first 1 cm or so... that's when it won't rev past 2100...
I also found ax gearbox had but a shade of fluid and was driven about 100km at least in that condition (effectively only with a coat if fluid in the gearbox)
If anyone has any suggestions, I'd really appreciate it.
As I've said, did a lot if research, read a lot of threads, none seem to fit exactly what I'm experiencing...
What would be your suggestion in progressively and methodically eliminating potential causes?
MAF?Pedal sensor? Fuel starvation? blocked cat?
thanks.
R

wrong section try posting over in the xj forums I am sure someone will try to help
_____ooooo
/__l_l_,\____\,___
l_---l_l__l---[ ]llllll[ ]
_.(o)_)__(o)_)--o-)_)

it has no cat
You have posted in the correct place. Ignore people who dont have a XJ diesel.
I take it you have replenished the gearbox oil. Probably will be ok as long as it is not making lots of noises.
Sounds like it needs a good service. Change all fluids ~ oils- engine, gearbox t/f case, diffs, brake fluid, coolant, & all filters- engine & fuel.
then see how it goes.
it may have a blocked fuel filter.
What is the throttle body you speak of? You could try blanking off the EGR.
What is with the acetone? as it is a strong solvent it could damage the electronics inside the IP. Dont use snake oils.
What is your location? Some times members can suggest people near to you who can help.

I've heard about the acetone being pored in diesel ...Myself never tried it .
But I do pour 200ml of 2 stroke oil in the fuel tank at every fill up.
It could be many things with your car but sounds like fuel related .
As Layback sugested check or change fuel filter (start with the easy ones),
Make sure there is no air /air leak or water in the fuel system.
Next would be to check the crank shaft sensor on the bell housing above the flywheel if not loose or faulty (unlikely but never know) .
Have a look at wirring if not rubbing against each other or chasie .
Check and clean the MAF sensor .
Pull the tank fuel supply hose of the fuel filter and blow in it to see if not blocked , should hear the air bubles in the tank .
It sounds like engine is starving for fuel . In the same time have a look at the sensor on the accelerator pedal and check for damage or wirring fault .
Worst ...it would be the IP but unlikely (quite robust).
A bit hard to pin point your problem . Hope you'll manage to find the problem and let us know .

Hi
Thank you fimor helping me
- I'm in Brissie area, Strathpine
- I think it does have a cat, unless it's a small primary noise dampener - it's just before the central locker
- you're right - not throttle body - I've sprayed into the intake manifold after disconnecting the hose coming from the air filter, layback40
- I do think might be a fuel delivery problem as you say, amlav
- I will try everything you gents posted as a logical step by step, engineering type troubleshooting

However gentlemen... Might have a bigger problem I need to kindly ask fir guidance with...
Last week I had a horrid and unexpected situation.
I have an AX-15, as I said before.
After replenishing fluid and changing after a week with 10w-40, took it for a spin to Bribie (Whorim) , about 100k round, both town and highway conditions.
Stopped there had brekkie and a leg stroll on the beach.
Drove back, about 3 k from home would not shift in 3rd or 4th, would grind and seriously kick the stick to the extent my hand3 would hurt.
Drove home in second. 1,2, easy as - 3 or 4 (tried double clutch and skip a gear) would grind and kick back big time.
Left it a couple of hours then went to the BWS to get some pack to drawn my sorrow, and shifted fine in 3rd . On the way back (it's 1km either way) stopped getting into third again.


Today (after a week) I went on the same round 2km trip to BWS, shifted like butter into 1,2,3,4,3,2,1 multiple times, zero issues, zero grind.

I'm puzzled... should I change the gearbox fluid again? I'm seriously at a loss. Both my son and I love the damn thing to pieces, but I don't know where to start with either power loss or this weird gearbox prob...

Could they be related?
Could it be fluid, syncros, clutch, clutch hydraulics?
Sorry to add to the list...

R

And yes, no noises on the tranny...

:o:rolleyes: It does not have a cat !!!!!!!!!!! If you looked at it properly you would see the thing you are looking at is a flexible joint. Probably you lack the knowledge to understand these things. The VM425 is not set up to take a cat. They didnt put cats on diesels back when it was built.

You need to have it properly serviced by someone who actually knows something about diesels. Best stop driving it until this is done. You run the risk of doing some serious damage.

Have you checked your clutch fluid level? This should have been done before you drove it.

You cant fix your jeep by posting on the internet. it needs to be looked at by someone with experience working on them. The diesel is completely different to the petrol ones. Like most XJ diesels that have been not looked after mechanically, yours needs a bit of trouble shooting & fixing.

Gear sellection problem could be :Clutch , clutch fluid low level, clutch hydraulic cylinder, low or wrong gearbox oil and another thing that i come across is the gear sellector lever .
Gear selector lever has a small plastic bit at end that goes in to the gearbox and that had small bits broken of it causing same symptoms as yours . The broken bits sometimes where jamming the lever travel .
Fairly easy to check that one : remove center console , undo a few bolts holding the lever assembly and gently pull it up and remove it from gearbox . It is a square shaped plastic thing in which the ball shaped end of lever pop in to . Again this are only sugestions that I think would help . If nothing else than it is a gearbox off job and check everything starting with crankshaft end play, clutch and so on ...
If you download the manual it would help and also Youtube in some cases .

Layback40 - Understand - I'm trying to learn as fast as I can, this is my first Diesel ever. But as far as I read, not a lot of shops are familiar with the XJ 2.5 VM Motori. How would you suggest I find one north of Brissie? Same goes for the manual transmission - my second car with one, last was in 1999.
Also, I get your point re catalyst converter, but the factory manual describes one for the 2.5, unless it's possibly in the context of a petrol.

Amlav - thank you - also understand. I did read about the plastic bit, I'll check that out - would it happen only when hot?
I do have the fsm and a separate pdf dedicated to the ax-15.
I tried to look for the clutch fluid reservoir and I can't find one.

While I respect your knowledge gentlemen and your helpful suggestions, and while this is indeed a manual and a diesel which I'm not familiar with, I'm not totally incompetent when it comes to mechanical work.
I do everything on my ZJ myself, I've done two head gaskets, replaced power steering pump, managed to fix enough to limp it to the nearest sealed road twice, once on Teewah and once at Poepples corner... Nobody helped me, and the head in the ZJ is solid iron ;)

R

Ok found the clutch reservoir, was full to the point it leaked when opened (had to use a plumber's pliers)
Liquid looks clean and transparent...
I couldn't see the reservoir initially as it blends with the firewall and other parts, being black...
R

6 posts in nearly 11 years boy you are quiet
welcome hope to hear more from you
_____ooooo
/__l_l_,\____\,___
l_---l_l__l---[ ]llllll[ ]
_.(o)_)__(o)_)--o-)_)

Hey LuluBelle
I did the same looked up when forum said I joined and went , n waaaaaaat?

Good point. might mean one or both things
either this forum is awesome ( which it is!) meaning you get answers to pretty much ANYTHING if you know to search
And/or
The creepers are so reliable that one might just not need to ask...which the are.
So believe you ne, wasn't easy to post but humble pie half eaten, don't have no place to ask or take no more...
Not happy, not proud, it is what it is.
I'm fluent with my 4.0 auto ZJ with 240k, done Simpson twice, done Walker's crossing twice, went to Perth and back via my dare Uluru and great central, than back through Nullarbor and Moree.
Wouldn't have easily asked mates if I wasn't to the ends of my whits with this particular xj.
I got a good trusted tranny guy, I'll call him tomorrow, this takes priority over lack of cojones uphill..
R

QLD has more XJ Diesels than any other state in Australia so there is a better chance of finding a good mechanic there. I would never take either of mine to a Jeep dealer. VM made their name in marine engines & then industrial applications. The Xj engine was an industrial engine supplied to jeep. you may wish to talk to mechanics that do work on diesel boats. Once you understand the engine its not so complicated. Your knowledge about the petrol jeep is probable a hindrance. The manual trans is used in other applications, IIRC some jap stuff. its a very simple 5 speed manual box. Interestingly its a 1990's style box. As yours is not making noises, chances are your problems are only minor. If I dont push the clutch peddle down far enough either of mine wont go into some gears. it is also possible that your master/slave is on the way out & when warm is not putting enough pressure on the clutch. Been there done that! If you pumped the peddle up & down did it go into gear?

If there were aftermarket iron heads for the VM, i would have fitted them years ago. The heads are the weakness.

When some one with experience with these posts something, best not dispute it. I have 2 of them & over 300,000km driving/maintaining them. i think I would know if they had a cat. My manual has no mention of a cat in the diesel section. The 2 most knowledgeable members, Mudmonster & Dieselweasle dont post any more & may have left AJOR. While a few petrol XJ owners may offer help. They have very little knowledge of the engine & gearbox & seldom can offer much other than moral support. Many owners manuals & parts books have mistakes & are meant for the 2.5 petrol. Info from the USA is unreliable as it was never sold there. Never listen to the people at supercrap. Their parts info is nearly always wrong. They even tried to tell me there was a non turbo 2.5 XJ diesel. Triton info is also normally wrong. Much of the Crown (USA) is wrong & meant for the petrol 2.5.
Most parts I get from Europe. The engine was used in many other cars including Alfa, Rover & Ford there as well as things like street sweepers & other industrial things. There is a Facebook group for the VM engine based in Europe, the members are very helpful but you will probably find them to be old school die hard diesel people.

somewhere I read (a somewhat oddly worded) post from Dieselweasel,

saying (words to the effect) he would not be answering questions on here anymore

There was another post here by Luminol related to gear shifting issues .
It sounded like the clutch master cylinder needed bleeding but he never came back to let us know to confirm it .
Croitoru... don't despair , just take it easy . Pull apart things and examine . You won't get answers that would pin point how to solve your issues just suggestions . People here assume that op's get dirty and rip in to it until problem is resolved . You sound a keen guy not afraid of oily hands and therfore I would say don't be afraid just rip in to it bit by bit and be calm ,don't rush .

Hi
Finally life gave me a break and took it into my trusted transmission guy, Clint@Hart transmission in Brendale (thank you state if Queensland for Ekka break).
I had to drive there in second, of course.
Then he took it for a spin and managed to shift it in 3rd, 4th, 5th, multiple times. By slightly pulling the shifter up.
He said there's likely nothing serious.
I'm going to ask him if he knows any good diesel mechanic up this way.
I will post results re transmission final root cause and fix as soon as I have it.
Cheers,
R

Regarding the gear shifting : It is very easy to remove the gear lever unit from the gear box (from the inside of cabin) . Remove center console , remove the rubber cover edges and push rubber cover up the lever .
There will be as far I remember 4 bolts to remove and the lever should come out. At the gearbox end of gear lever there would be a small plastic type coupling (squarish - that was broken on mine).
As you select the gears the coupling slides and moves the gearbox forks inside . Maybe it's worth looking at it .
That would be pretty much all you would be able to inspect the rest would be to do with gearbox internals .

Amlay - thank you.
Turned up it was the plasticky thingie you suggested... but wait, there's more!
The selector fork was funked, deep groove (aluminium) which explains the shiny look if the first gearbox fluid change.
And while at it, the clutch was kooked as well, also clutch springs broken... also seals ( including rear main)... rear lsd rebuilt (broken metal bits floating in the fluid, cracked gears, etc)
So a lot replaced and Clint reckons drivetrain good for 200k km now...cost, better left out of the discussion. He's really good so he cut me a deal. Took it for a drive up Mt Glorious today (and have been driving it daily for a week) all good, still a heavy manual truck. Climbed and drove fine as long as I kept rpm bellow 2k.
However...I asked Clint and he took it to a diesel specialist mate at the same time, but no cigar. No codes, tried egr blocked/unblocked, etc. It's clearely fuel restriction above 2000-2100 rpm. His mate scratching head, said either injectors or fuel filter.
Not sure what to do next, I guess fuel filter (no idea how old/condition, so might as well)
The more I drive it, the more it feels (of course could be placebo) that it gains just a bit more rpm before it starves.
It's clearely a fuel delivery problem because I drove behind it in my ZJ and I can see very little and very seldom any smoke even when downshifting on climbs.
It FEELS like an electronic sensor problem, restricting fuel at 2k+ RPM.
R

Glad to hear that part of the issue was fixed . To try and sort out the fuel issues I would start with replacing the fuel filter .
Make sure there is no air getting in to it (seal has to be perfect).
Air also can get in the fuel system if injector(s) are faulty and don't close properly .
Fuel filter issues still would allow the engine to rev up in neutral but maybe not under load .
Clean the MAF sensor and replace the air filter .
Check number 1 injector by measuring the coil reading (should be arround 120 ohm) . If there is no reading than that could be the problem . Engine management computer will not let engine to rev up over 2000 rpm if doesn't get the signal from the needle sensor inbuilt in to injector 1 . Also check the electrical connections on it - including connectors too).
Some say that sensor can be baypased connecting a 100 ohm resistor in parallel on the 2 wires . (not sure about it , mine is still ok ).
If all above ok than only thing left would be injection pump (hope not).
Can you rev it up over 2000 rpm in neutral ???

Actually that's a very good point, and thank you for highlighting.
It's probably the relevant engineering differentiation I should research on.
Based on your hint, Amlay (thank you), I realised that the fuel underdelivery issue ONLY happens under LOAD. I don't know what it means yet, but It think it's a HUGE troubleshooting clue.
Revs fine (3000+ rpm) and have (some) black smoke in neutral, stationary.
So I guess perhaps the next step would be to understand what sensors come into computer calculations as input for load-based decisions, and go from there? I've checked #1 resistance before and seems fine, but the wiring looks like it might have been worked on before (possibly same troubleshooting?). Maf looks clean but I will recheck. Also, I bled the fuel pump before didn't make much difference. I also guess airfilter and maf would cause the same issue both under load and in neutral? Although you say that fuel pump/injector could cause this exact behaviour ( RPM fine at neutral but limiting under load).
R

Have you replaced the fuel filter element yet? No point in any further trouble shooting until you have done that. When you replace the element it would be worth blowing back the fuel line with compressed air. Make sure you have the fuel filler cap off when you do it. This will clean any blockage out of the strainer in the tank.

Sounds exactly what mine was doing a few years ago , turned out to be a faulty Map sensor in the inlet manifold... try cleaning if not replacing

ok...life doesn't seem to give me a break... work was mad but most annoyingly, got the gearbox fixed for about 8 weeks then...
XJ 1998 VM - stopped going into 3rd - again - stripped fork. They replaced pressure plate, said take in again after 500 to 1000k for check.
Original problem- on original topic - got a Bosch scan from SCE Lawton today (no engine check light if course;) that picked up P1660 , which seems consistent with behaviour.
This guy seems yo have travelled yhe path...
http://jeep-club.co.uk/viewtopic.php?t=6623

Another bad news is that my ZJ is making rear end noises, lent it to my gf for a week got way worse...diff oil spilling out of rear...will have to take a look.

I hate when people post and ask for advice then once their issue is solved they never post back... so yeah, I'm slow on progress updates, but I WILL post back until the issue is solved.

@laydback40 - I think you're right ... I've thrown away everything I know about petrol and trying to learn diesel...It would be fun if it wouldn't be so painful at the moment �� Thank you, it's the right mindset change...

Can I ask how did you clean it please?

ok... p1660 FM details are at odds with the link posted above...
http://zinref.ru/avtomobili/Jeep/100...NGLISH/623.htm
wonder if I should just get a complete pump? Anyone has a good second hand one?
Love the truck but it's driving me nuts instead of me driving it nicely...

Spare MAF swapped. drove disconnected for test, drove like crap, so not that.
Fuel cuttoff valve changed - code didn't come back...so not that
Fuel and air filter changed - fuel filter bled - so not that.
Oil and oil filter changed - so not that
Injector #1 resistance is 117 Ohm, so probably not that.
Currently running diesel cleaner and acetone in tank.
Still throws back like a rubber band when going uphill and hitting ~2000 rpm - loss of power... don't have to downshift, seems to be self regulating, I can climb in 4th and 5th but at at steady ~2000 rpm and 60-80 kmph.... if it's to high will slow down then kick power back in and climb steady as long as it stays around 2000 rpm.
I'm running fast out of ideas and research. It obviously only happens on incline or under engine load - seems relatively fine on flat and definitely a rocket with the even slightest downhill...

I've just replaced my injector no 1 and next I want to measure the signal level coming from the needle sensor coil with an oscilloscope (just so I know ).
There is a chance that your signal from the needle sensor doesn't gets to the PCM (wiring broken in the loom maybe or loose contact ).
Before replacing pump have a good look and see how you go .

There appears to be a fuel supply flow issue. If it was me, the first thing I would do, is with the tank under 1/4, take the filler cap off, disconnect the fuel supply hose from the filter & back pressure the line with compressed air, say 100 psi blast, this will blow any stuff restricting the pipe back into the tank.

Thank you, I'll do exactly that.
I've taken apart the pedal sensor as well today, looks ok, cleaned with electric contact cleaner, put some graphite on it, and some dielectric grease on...no change.

R

http://www.ausjeepoffroad.com/forum/...f1f5fa7600.png

This is my step by step elimination process based on the feedback from you (thank you) and research...
R

Good point, thank you - voltage and signal not same thing...
Not sure where I'll get to borrow an oscilloscope, and I'll have to check pins to the controller modules (looks like there's a pcm jeep and an ecm bosch! working together...or not quite.)
Thank you,
R

PCM is next to the engine on top of the wheel well.
ECM is between the firewall & the heater in the cabin.

Blew the fuel line backwards, tank was bubbling for good 5 min...no change...

Ok...
So not having access to an oscilloscope, me thought let's disconnect no 1 and go for a drive...
No change in behaviour with the power loss!
So I guess now it's narrowed to the signal from no 1, either in the loom from connector to pcm, or injector itself (although it measures 117 as mentioned before).
I'll pull out the manual and see how I can test the connector to ECM segment... there.must be some expected voltage at #1 circuit...
R
http://www.ausjeepoffroad.com/forum/...fe2bb1cd0e.jpg

Ok...
Tested socket to loom to ECM with #1 disconnected
1. key off, engine off - 0V
2. key on, engine off - 11. 5v
3. engine on - 12.5v
TBH I thought I'd find no voltage and an open circuit.
Measured resistance as well varying from 7.5kOhm to 17MOhm, not sure what it means.
I need to figure out and understand how the no 1 injector signal works, varies (if) and feeds the ECM.

I think there are only a few possibilities
1. As above, even if measuring resistance ok "at rest", maybe at run-time, signal doesn't match ECM expectations - ie, faulty #1 injector
2. Above values on harness are unexpected and show a fault with wiring or ECM port
3. All is actually well, ECM is in limp mode and might need a specialised DRBIII tool/procedure to erase.
4. 117Ohm might be too high (understand 90 to 100 is expected value)
5. ECM is f-cooked.
6. It's already in limp mode for unrelated reason/ongoing fault therefore the above is all good but irrelevant and getting overriden by current state.

I intend to get a handfull of resistors varying from 70 to 150 Ohm from jcar and see if anything changes.
And I'll do more research, including fsm on what are expected values on the circuit.
Lastly, once I go through the above, I might run paralel wiring directly from #1 to ECM.
I'll also try to understand how the ECM interacts with PCM (if at all)

BTW, I've amassed a bit of PDFs if anyone needs anything ...

R

OK.

"NEEDLE MOVEMENT OR INSTRUMENTED
FIRST INJECTOR—ECM INPUT
This in put fr om t h e ECM su pplies a con st a nt 30
mA elect rical cu r r ent sou r ce for t h e fir st inject or sen -
sor. It will va r y t h e volt a ge t o t his sen sor wh en it
sen ses a m ech a nical m ovem ent wit hin t h e inject or
n eedle (pintle) of t h e n um ber –1 cylin der fu el inject or.
Wh en t his volt a ge h a s been det ermin ed by t h e ECM,
it will t h en cont r ol a n out put t o t h e fu el timin g sole-
n oid (t h e fu el timin g solen oid is locat ed on t h e fu el
injection pum p). Also r efer t o F u el Injection P um p for
a ddition al in form ation.
Th e fir st inject or sen sor is a m a gn etic (in du ctive)
type.
Th e fir st inject or sen sor is u sed only on t h e fu el
inject or for t h e n um ber –1 cylin der (Fig. 4). It is n ot
u sed on t h e inject or s for cylin der s n um ber 2, 3, or 4.
FUEL INJECTOR SENSOR—GROUND
P r ovides a low n oise gr ou n d for t h e fu el inject or
sen sor only."

Amlav, I'm with you now...very hard to pinpoint. I will check the Crank next, as Ive exhausted everything else but a turbo boost leak now...thank you.

Ok... plot thickens.
I'm leaning towards this now:
6. It's already in limp mode for unrelated reason/ongoing fault therefore the above is all good but irrelevant and getting overriden by current state.
Specifically, fly-all boost pressure in intake (turbo works though)
Reason ( correct my potentially biased thinking please):
I went and bought a SaaS 30 psi boost gauge.
While examinining where to fit it I found this tap on top of the intake mainfold:
http://www.ausjeepoffroad.com/forum/...04e860497c.jpg
Not a fit, but as I did with disconnecting inj #1, I loosened the bolt creating an artificial leak... (blew and lost the bolt in the process though, thus far). Principle of either fuel, air, or spark missing ( last obviously not applicable to this!)
No change in behaviour with or without that in place!
http://www.ausjeepoffroad.com/forum/...04f0d387b1.jpg
So I think the turbo hoses, intercooler and possibly turbocharger comming off next... As little as I know about diesels and turbo, that's definitely consistent with a leak
R