NF v6 stalling

[OlgieD]

Hi Guys,
Looking for opinions/ideas.
My 89 NF v6 Pajero had some work done recently (rocker cover/valve seals replaced, sump gasket replaced, and some other works) and since then, it stalls intermittently. When it does, it cuts out like the keys has been turned off.
When running it runs very well. Smooth idling (around 500rpm), and accelerates well. The mechanic who did that work stuffed up the rocker casket though and let me drive off with a new leak. Throwing oil every where on the engine. I ended up going to another mechanic who replaced the rocker gasket (again) and fixed the issue. The first mechanic had a stalling issue at some point too, just as they thought they were finished. He reckoned they stuffed something up with the camshaft, where it had jumped a tooth. I'm not entirely clear why that would be the case though, as they shouldn't need to touch the camshaft and timing belt to replace the valve seals afaik.

When I picked the car up from the second mechanic, it drove like always. At some point I needed to turn off and had it idling for a minute while waiting for traffic. The engine just died. Still cranked but wouldn't fire up. After 20 or 30 minutes, and multiple tries, it started running again. Kept going and drove another 150k before it died on me again.
This time I was going uphill at 70-80kph, when at the top (still had my foot on the accelerator), it just cut out.
No spluttering like it was short on fuel, more like turning the engine off using the key.
Fired up a couple of times and I was able to keep going for a little more, but ended up calling RACQ to get me home.

There's a strong spark when it runs, ignition coil seems fine, spark plugs have just been replaced (first mechanic did that). When it's running, it runs sweet. There's no moisture in the distributor cap at all (engine has been cleaned a few times because of all the oil).

Is this likely an electrical issue (ie, bad coil, capacitors, power transistor), or would this be more a fuel delivery problem?
To me, if it were a fuel delivery problem, it would splutter as it's starving on fuel (fuel filter has been replaced not too long ago). Not cut out instantly?
And if it's electrical, where to start looking? When it's running, it runs fine, so it must be something that's not completely broken. Which makes it hard to diagnose.

Any ideas and thoughts welcome!

[nj swb]

This sounds like classic crank angle sensor problem.

The crank angle sensor tells the ECU that the engine is running. If it stops sending pulses, the ECU decides that the engine has stopped running, so it stops firing injectors and plugs. No error code, because the ECU doesn't recognise that the sensor has failed.

[OlgieD]

This sounds like classic crank angle sensor problem.

The crank angle sensor tells the ECU that the engine is running. If it stops sending pulses, the ECU decides that the engine has stopped running, so it stops firing injectors and plugs. No error code, because the ECU doesn't recognise that the sensor has failed.

After reading up a bit about the CAS, it does seem plausible. The RACQ guy that dropped me and my car off at home had a quick peek under the hood before he left. He checked for a spark from the coil, and got none. We talked a little after that, and then I cranked the engine and lo and behold it started. We cut the engine, and he checked the spark from the coil again and now it was there nice and strong. Threw him off. :-D
But can a CAS be intermittent faulty?

Found this website that has troubleshooting for the 6G72 engine: http://easyautodiagnostics.com/mitsu...system-tests-1
Will check that tomorrow.
Also, I noticed that the timing is rather odd. I've got a strobe test light and noticed that at idle (around 500-700rpm) the notch on the crank pully is about 20-25 degrees before the indicator on the tab. I haven't been able to find info on how to check the timing correctly though, I know not all engines are at idle rpm.
Any thoughts?
Thanks heaps for your input!

[stumagoo]

I would also be checking all the electrical connectors around the engine and the earths. these symtoms could easily be a plug not properly seated. (not saying it is but its a 10 minute job to go over everything and it is minimal cost. other than that I am inclined to agree that its likely to be timing related, something either in the Dizzy or the CAS. Final option is maybe the coil is breaking down under load/heat and needs to cool down. Long shot but I have known it to happen in older cars

[OlgieD]

I would also be checking all the electrical connectors around the engine and the earths. these symtoms could easily be a plug not properly seated. (not saying it is but its a 10 minute job to go over everything and it is minimal cost. other than that I am inclined to agree that its likely to be timing related, something either in the Dizzy or the CAS. Final option is maybe the coil is breaking down under load/heat and needs to cool down. Long shot but I have known it to happen in older cars

Before I bought this Pajero I had a similar manual one, and at some point I bought a broken Pajero on ebay for parts. Then my manual broke down and I sold that on ebay, and happened to purchase another Pajero (current one) which was exactly the same as my parts Pajero. Even the same color. :-D
I kept a lot of parts and sold the body, one of the parts was a working distributor unit. That's in the car now and I've driven about 100k's today without a prob. Also have a spare coil and power transistor and will keep that in the car for a while.
Fingers crossed the crank sensor is what caused the probs, but so far it seems to be.

Thanks for the feedback!

[geartwister39]

glad to read your post

hi im new here and new to pajero / montero. in any case mine has just starting doing pretty much exactly what yours was , stalling out of nowhere and not starting , no spark ect. just put new fuel pump and filter (petrol) im in the usa cant find any info on these suv's . i love my 89 3.0 4 door 5 gear 4x4..dont mind buying parts if i know what i need she has 304000 miles on her .. so far paid for 2 tow trips. that offends me.. anyways so happy to join this forum. i want to eventually make this a nice ride as time and money permits but first i need my ride to be reliable as it has been . so i will definently read alot of the tech info as i work on and build my own cars.

[OlgieD]

hi im new here and new to pajero / montero. in any case mine has just starting doing pretty much exactly what yours was , stalling out of nowhere and not starting , no spark ect. just put new fuel pump and filter (petrol) im in the usa cant find any info on these suv's . i love my 89 3.0 4 door 5 gear 4x4..dont mind buying parts if i know what i need she has 304000 miles on her .. so far paid for 2 tow trips. that offends me.. anyways so happy to join this forum. i want to eventually make this a nice ride as time and money permits but first i need my ride to be reliable as it has been . so i will definently read alot of the tech info as i work on and build my own cars.

Glad the info helps someone. It's been 5 months since I replaced the distributor unit, and it hasn't failed me once. Unfortunately those units aren't cheap, but I dropped a secondhand one in and thats working fine for me.
Welcome to the forum!

Cheers!

[geartwister39]

so now i am 5 tows home now losing a bunch of money and patience... so after my last post i put in a brand new dizzy .. had to even rewire it as it had the right color wires in the wrong location on the plug
got that fixed then went to drop in new dizz... finnaly got her fired up again then the same @@###$%^&*^* thing happens.....no spark
dropped ecu found 3 relays found out 1 is for 4x4 1 is for fuel and 1 for engine control
my Haynes book wiring diagram was completely wrong that book is useless
we tapped in the power wire on the dizzy side pulled 12v off the batt and she fired right up
now im inclined to put a toggle switch to dizzy power but also worried about 12v burning my dizzy up. im no electronic person this %$#@ montero has me all kinds of messed up.so im tired of buying parts not sure if its the engine relay or ignition switch or main computer..i need to fix this. it goes against everything i know to bring it to a repair shop LOL oh yeah the last tow was for free! the driver felt sorry for me , i guess i racked up frequent flyer miles aslo put a new electronic module on it too

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[TomW]

I have attached a copy of the wiring diagram from the 1989 factory manual which may be of some help. Have a look at page 36 (8- 56 MPI circuit). It looks like the distributor runs direct from the ECU?

https://drive.google.com/file/d/1gpjUbAthScKAiir698lWgTAxFcQ9HRFO/view?usp=sharing

[geartwister39]

my buddy from work found a good wiring diagram and got it figured out and thank you big time for the help that lead on the dizzy takes full battery voltage so i should be good to go now

[old dave]

Perseverance and being methodical will overcome your fault.
There are heaps of used parts available here in Australia which makes it easy for us.

maybe it is the crank sensor ? The CPU will cut volts to the fuel pump as well if the crank sensor has a snooze. Mercedes made a heap of cars of the late 90's early 2000's where the crank sensor was almost gauranteed to die..

I have had my 1989 V6 for a few years now... I bought it with low kms 200,000...but it had been run into the ground. i took the heads off and valve guides were replaced. one had come loose and dropped half way out. biggest issue was cleaning years of congealed oily mess off everything from numerous serious oil leaks.. The left bank of the motor had about a bucket of sludge in it and it blocking coolant flow to the back of the left cylinder head.. I used a pressure washer to blast every coolant channel(and the odd oil feed channel) and blew it all out onto the carport roof
It took about a year of hobby project time to get it back running as it should..

First trip out and doing 100kph it just cut out. 10 minutes later it started again and I got it home.

Took the fuel filter out and got covered in liquid mud and petrol...it was full of dirt. That has been my only problem apart from a head welch plug falling out.. it survived... and I got to do a lot of my work again..except I did it better and faster.

Ignition timing... I set it up by the book but it was missing power..I just advanced it until it sounded happy and have left it there.. and it goes very well and is almost economical and very reliable.