Electrical issues following wash - need help solving mystery

[sk66]

I know I'm not helping much...
If the mechanicals of the engine are all fine then it's not mechanical "resistance" internally.

Spark at the wrong time won't cause engine cranking to slow down, nor would fuel being added at the wrong time. That would/could prevent it from starting; not build up resistance.

But both at the wrong time could cause combustion during the compression stroke, which would create resistance (and can destroy an engine).
The most likely cause that I can think of is the crank position sensor, followed by the ECU; but you said you have tested both and replaced the ECU... maybe try swapping in another sensor?

 

[Gandalf]

I know I'm not helping much...
If the mechanicals of the engine are all fine then it's not mechanical "resistance" internally.

Spark at the wrong time won't cause engine cranking to slow down, nor would fuel being added at the wrong time. That would/could prevent it from starting; not build up resistance.

But both at the wrong time could cause combustion during the compression stroke, which would create resistance (and can destroy an engine).
The most likely cause that I can think of is the crank position sensor, followed by the ECU; but you said you have tested both and replaced the ECU... maybe try swapping in another sensor?

So an update on timing,
Tested timing during cranking with fuel relay unplugged (to help save the new starter), and timing is way off. Coil 1&4 (center coil) with timing light hooked up shows around 240 degrees advanced (or 120 deg retarded). huh?. It was very difficult to find, hiding behind the timing belt. That coil only fires once every two crank revolutions, or once every cam gear revolution.

On the cam gear, the timing light TDC mark is at about 120 deg advanced (which coincides with the main crank at about 240deg advanced since the cam gear turns half as fast).

So, if the timing belt has not skipped any teeth, and the cam sensor (TDC) is reading correctly and outputting correct voltage at the right times with the cam trigger large tooth just entering the sensor, as indicated in the wave pattern (on p253 Montero manual) as being correct, (and has even been swapped out), the ecu has been swapped out, what can cause the TDC to be so off?







Something must be drastically delaying the TDC cam signal, ether after it is sent to the ecu, or the ecu signals are being delayed after they have been sent to the coils. Plus, the strange coil firing patterns.
The crank position sensor signals are only 75 degrees separated, and the maximum they could be out by is 60 degrees... so it is increasingly unlikely that the crank position trigger wheel being off is the culprit (I have not dismantled the engine to look... it is much harder to fly blind once you take stuff apart since you cannot verify by attempting a start).

 

[DustAngel]

I believe each coil should fire at least twice per cam sprocket revolution being that the coil is responsible for two cylinders? Is there a bad wire between the ecu and the coils? Thinking something in the engine wiring harness as best guess

 

[thelazygreenfox]

Thank you for the reply, and the info.
I would love the actual Delica v6 6G72 manual (series 2)... I have looked everywhere, tried to buy them when advertized as including the v6 6G72 engine, and they have all been ripoffs (just what is commonly available in the diesel engines etc). I can piece together some things (like the Magna, but it has a distributor), and the Montero (but a different ecu, different ecu plugs and pinouts)... so far no way to trace all of the ecu harness wiring to verify continuity.
Interesting on the boosting info... what about the stealth twin turbo? Not thinking anything crazy, just another 50-70 whp (6psi etc).

This about as good as it gets. You'll have to read out the diesel, L300 and left hand drive sections and read in the L400 V6 6G72 sections and sometimes under pajero. PITA but a right of passsage.

To the best of my knowledge most manuals came from Delica.ca. Falco found them somewhere and loaded them, I've been using them since. I believe Growlerbearnz loaded them from Delica.ca. He is still a delica.ca global moderator as am I. Still a good site but not used so much anymore.

I tried to load the delica.ca files for you but they're too large. https://drive.google.com/drive/folders/1O45g4Gs4s8rPIEafx2JymXAxZR5xhLkZ
or load them from delica.ca Resource L400 section..
good luck
thelazygreenfox, mobydick
Wayne

 

[Gandalf]

I believe each coil should fire at least twice per cam sprocket revolution being that the coil is responsible for two cylinders? Is there a bad wire between the ecu and the coils? Thinking something in the engine wiring harness as best guess

Yes correct, 2x per coil per cam rev, or once per coil per crank rev... which is part of what is so odd. But no bad wires. I swapped out the entire coilpack, verified wiring continuity and independence for each coil wire (except for the shared power supply), then got anal about remotely possible "crosstalk/interference between the wires and separated them from each other completely from the ignition control module to coils... no difference.
Verified continuity in the coil signal wires from ecu to ignition control module, and no unwanted continuity from those 3 with any wires in the other plugs that I could find.
Plus, the signals are not intermittent, as they might be if the connections were sketchy. They are consistent, and the timing is just way off, inexplicably. But I will swap some individual coils between the coilpacks just to be sure.

 

[Gandalf]

This about as good as it gets. You'll have to read out the diesel, L300 and left hand drive sections and read in the L400 V6 6G72 sections and sometimes under pajero. PITA but a right of passsage.

To the best of my knowledge most manuals came from Delica.ca. Falco found them somewhere and loaded them, I've been using them since. I believe Growlerbearnz loaded them from Delica.ca. He is still a delica.ca global moderator as am I. Still a good site but not used so much anymore.

I tried to load the delica.ca files for you but they're too large. https://drive.google.com/drive/folders/1O45g4Gs4s8rPIEafx2JymXAxZR5xhLkZ
or load them from delica.ca Resource L400 section..
good luck
thelazygreenfox, mobydick
Wayne

Thank you, will continue to research.

 

[Astromike]

I have a 1994 v6 l400 s. Here in the states alot of mechanics have this scantool. It worked in mine. Hope it can give you some input in the rightdirection. I've read the entire thread.

 

[Gandalf]

I have a 1994 v6 l400 s. Here in the states alot of mechanics have this scantool. It worked in mine. Hope it can give you some input in the rightdirection. I've read the entire thread.

Thanks for that tip. I almost acquired the above unit, and yes it does seem to cover the earlier V6's, but unsure of the '98's, would have been good to find out, but I managed to solve it without. See below.

 

[Gandalf]

UPDATE: SOLVED
I've been meaning to update ya'll on what actually happened. And thankfully it was a clear Ah-HA moment.
As described above, I proceeded to pull off the intake manifold and change the plugs/wires.
Put it all back together... No difference. So it was not some random massive IGN ground/fault loop as the cause.
I did tighten some loose valve cover bolts while I was at it though.

The remaining conclusion was that, although I was getting what seemed proper signals from the crank position sensor with hand-cranking, perhaps it was sending erratic inconsistent signals when getting triggered rapidly. Besides, it was the one sensor I hadn't swapped out yet. And then I did a test of my own... I plugged in a spare crank position sensor (leaving the installed one disconnected), and got my wife to crank the engine while I triggered the new sensor randomly with a piece of sheet-metal. I was able to reproduce the problem, some labored cranking moments and slight combustion hints. This gave me the confidence that I was on the right track. Perhaps the sensor had broken off somehow and was out of position?

So I proceeded to pull off top two coolant hoses, rad shroud and viscous-coupling fan, to get at the main pulley.
Well, things got funny already right at this point. I used the blip-the-starter method with a braced breaker bar to loosen the main bolt. It came loose no problem, but as I am wrenching it it feels funny, and suddenly comes out early... with its tip 1/2" missing (broken off). Because the sheared surface was discolored, I'm not sure it was I who just broke it. Well, I steady myself with a beer and proceed to tackle drilling out and extracting the tip. The beer helped because the tip was not seized at all, spun out immediately with the drill bit in reverse. LUCKY.
So this brings me to my first little rant about the main pulley bolt; terrible design. "Nice Try" engineering. Brutal. That long unthreaded extension section creates a long lever with the fulcrum located in the thread section. It is why Mitsubishi updated that bolt with a normal bolt later.
This broken bolt could be the cause of the issue, because of how the rest of the items on the crankshaft are designed. If the bolt manages to loosen (and that long disastrous bolt extension will also make it prone to vibrating loose btw) it will allow the timing gear to slide forward enough and the sensing plate located in behind it to shear off the tiny pins holding it in place.

So I pulled off the accessory tray and everything from the front of the engine, to get at the timing gear, sensor, and sensing plate.

So that's it. The tiny pins protruding from the back of the timing gear were sheared off, allowing the sensing plate to spin out of position, and create the way-off timing. The cranks position sensor itself was fine.
The shifted timing creates partial combustion at wrong moments, making the engine very hard to turn over. Repeated attempts strained the starter and killed it.

Since it's the first time I have touched the main crank bolt (besides turning the engine over by hand in clockwise direction), it was a previous owner/mechanic cause or neglect. I mean, the cause of the timing issue was the loose main crank bolt... which I suppose I could have coincidentally also broken off the tip 1/2"... without it being seized...

but I suspect it was related. Who knows.

I had a chat with Rocky Mountain Imports in Saanichton/Victoria, and they confirmed that they have also seen these broken pins on the timing gear, if the main pulley bolt comes loose.

But because the only thing at the wrong time was the spark, no internal engine damage is possible with this scenario. I tested my backup ECU as well just to confirm its operation, and it was perfect.

Then promptly did an oil flush and change, new filter; there was a lot of fuel in the oil from unrequited air-fuel-spark cranking and washing the rings.

For the record, engineering-wise I am not a fan of the whole arrangement on the crank nose; the one key keeps the timing gear in place, the sensing plate in behind is kept in place with tiny pins off the back of the timing gear, the main pulley is kept in place with one pin off the front of the timing gear, and then the whole mess is finished off with a terrible bolt design and then "fixed'' with an ungodly torque requirement. What could possibly go wrong?

The initial alternator dying issue was unrelated, as was the washing of the van. Just bad luck that happened nearly at the same time. The reason the van wouldn't start, then started and ran for two days, then refused to start again is because the sensing plate spun out of position once, probably temporarily caught back in position on the remaining nubs of the pins from the timing gear, then sheared them off for good.

Thanks all for reading/helping!