1998 S2 L400 V6 3.0 6G72 Not starting, mystery! HELP

Mitsubishi Delica L400 production commenced in 1994 -- After much anticipation, the L400 arrived on Canadian Soil in 2009!
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Gandalf
Posts: 28
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Vehicle: Delica L400 LWB 3.0 V6
Location: Vancouver Island

1998 S2 L400 V6 3.0 6G72 Not starting, mystery! HELP

Post by Gandalf »

Hello all, thanks for reading. Ok my main ride (daily, work) has been down now for two months.
Here is the rundown on what transpired, and what I have tried, and where I am now. This is very hard without a proper Delica '98 v6 Series 2 manual :/
L400 S2 ('98) V6 has been nearly flawless for 5 years. Washed the van, using pressure washer (just externally, not in the engine bay lol).
Van runs/starts fine. But two days later, it is dead in the morning. So something out of the blue is draining it, slowly, constantly.
Recharged battery. Starts/runs normally but now I started paying attention. Dead again next morning. Replaced with fresh battery.
Starts and runs fine, but battery light is now on. Voltage on voltage meter seems to wander, going higher than normal, up to 15-16 volts. Then voltage is low, 11 volts and decreasing. This looks like alternator. Battery warning light is on. Going to get a new alternator, it starts weird (like it is fighting something), catches and seems to run fine, I get a half a block away from home and it begins to run rough, then quits altogether.
Cranks over, but varies greatly between cranking effortlessly and cranking very slowly... the dash lights dim every few seconds as it really struggles hard to turn over (if I were to guess, it is getting weird resistance from incorrect firing order or something like that). Plenty of fuel in the tank. Does not catch. Does not seem to have proper electrical to ignition, etc or perhaps to fuel. I tow it the half-block home with my donor-engine parts truck.
- Swapped in new alternator. Same inconsistent cranking issue, dimming dash lights.
- no warning lights. No engine codes.
- Main battery ground and battery leads checked/cleaned, and to body. No difference. Visual inspection of visible connector plugs, all fuses.
- noticed that with the ignition disabled (via unplugging of the crank position sensor, or unplugging of the power transistor unit (that sends spark to the coilpack) the engine cranks over quickly, smoothly, and consistently, no dimming.
- cleaned the starter connections
- inspected the connections for the crank and cam sensors, and the power transister unit.
The next morning, the engine cranks fine and starts, runs fine... for two days. Timing light showed usual 5-8 degrees advance. Voltage perfect 14v. Then suddenly back to the same no-start inconsistent cranking.
So I start pouring over the cobbled-together manuals (1998 Montero 3.0L 6G72 and the Magna TJ manual) to test components.
- the power transistor unit tests fine according to resistance/continuity and 1.5v battery tests
- the ignition (power transister unit) harness tests fine with the #1 plug for the ecu (pins 11,12,13) continuity and independence all good, all show the same power with IGN-on
- power supply in the harness for the power transistor unit is fine with IGN-on (pin #6, 12v)
- I have not located the "tacho" signal wire at the ecu end (its got 4 plugs)... at the harness for the power transistor unit it is pin 5
- tested the ground for the power transistor unit (pin 4 in the harness) and it is good, temporarily ran a separate ground wire to make sure, it is good and no difference
- both power tranistor units that I have get quite warm with cranking, I assume the aluminum back is a heat-sink that sits on the metal mount...

- crank position sensor tests fine (hand-cranking the engine and seeing the 3 clear 5v signals per crank revolution (as per this good Montero test here:)
https://easyautodiagnostics.com/mitsubi ... sor-test-1

So at this point, I am concluding that there must be something non-mechanical (nothing internal engine-wise) that is creating these difficult to crank moments, like cyls firing at the wrong time as they are coming up etc... because it cranks perfectly without ignition operational, and seems easy enough hand-cranking the main pulley/crank and turning the engine over with elbow grease.

- coils all test fine, I swap them for an entire different set, no difference, wiring for all coils is good (both sets), voltage supply to coils is good (12v with IGN-on and 10v while cranking), primary and secondary resistances all test the same for all coils
- test the power transistor unit (ignition control module), as per all tests I can find (including the 1.5v battery test, it passes, but just to be sure I swap it for a "known good unit" from CCA... it tests the same (passes test) and behaves the same as the current one I own (but I do not have a scanner to test for wave-forms and square-wave voltage). I swap with a third brand new unit, verified, the problem is not the ignition control module.
- added additional (temporary and additional) grounds for the starter, battery... no difference

Over the next few days the starter begins to struggle. I took it out, it looked to have some cracks in the magnets, and some oil buildup. Cleaned it... but then a few nights later it dies while cranking. I think it was on its last legs and died trying to overcome the hard cranking.
I send it out to be rebuilt by a reputable rebuilder. They said it was toast both starter and solenoid. Swap the rebuilt in, with new everything including solenoid. Cranks spiritedly, but same inconsistent struggling cranking.
- I swap in a replacement ecu. Zero difference.

So I focus on the nature and timing of the spark. They are not the same from coil-to-coil during start-cranking. I test this with both my timing light, and by swapping in a brand new spark plug wire and spark plug, grounding it to the battery while I observe the spark in the dark, moving from one coil plug outlet at a time (so that only 5 spark plug wires were hooked up to the engine at the same time).
- Coil B (in the center) fires a spark every second, and it did it consistently.
- Coil A (to the right as looking into the engine bay) fires faster, twice as fast approximately.
- Coil C (the coil to the left) fired that plug 3x in the same amount of time.
Does anyone know if the Delica has a type of "batch fire" or "quick fire" for startup designed to know some Hondas have a startup "batch fire", mid-90's Civics for sure. I understood that to mean briefly firing all cyls at once... so this wo help for quicker starts? Iuld be different.
Just kinda 'firing' from the hip here, but, it seems to be robbing the other cyls of simultaneous spark power and possibly firing multiple cylinders simultaneously and at the wrong times, creating the difficult cranking because partial combustion is happening in the wrong part of the cyl travel (upwards).

I have not examined fuel issues with seriousness yet, because I can smell and see fuel mist from the exhaust, and fuel issues do not explain the difficult cranking or odd sparking. I do NOT hear a fuel pump priming with IGN-on... I welcome any fuel-related tips.

I conclude at this point that it could be:
- there are grounds that I have not found or tested?, like the ecu grounds (there are a number of grounds right beneath the ecu at the lower ecu bolt, they all look good and are cleaned), because from my understanding, the ecu is closing (grounding) the signals from the coils to fire them.
- there are relays that are IGN-related that I have not found or have no clue about?... and they can screw up spark delivery? from what I know, the ecu wires are uninterrupted by anything straight to the power transistor unit...
- there is a wiring issue that somehow is interfering with the signals being sent to the power transistor unit, like some power wire arcing into one of the three harness wires from the ecu (pins 11, 12, 13) but is eluding continuity and independence testing of those wires.
- two power transistor units from CCA are possibly both bad? (CCA calls it an electronic control module for some reason), and although two of them pass all resistance testing, they could fail waveform testing or otherwise are shorting inside, sending multiple simultaneous signals to cyls (and yes I know it is wasted-spark firing each pair of cyls 2/5 4/1 6/3 from each coil simultaneously, I mean it is firing coils simultaneously instead of individually)
- I need to buy a scanner that can indicate waveforms and other OBD2 stuff?, any suggestions welcome
- both ecus are bad, in the exact same manner (wow we are getting into statistical improbabilities here)
- there is a fuel related issue that can somehow create a cranking issue in a roundabout way ... but does not explain unequal sparking (this makes little sense, but I am open to enlightenment)..

Any thoughts welcome. Thanks for reading so much. I am located mid-Island.
Last edited by Gandalf on Wed Aug 17, 2022 6:21 am, edited 2 times in total.
Gandalf
Posts: 28
Joined: Sat Jun 25, 2016 4:56 am
Member's Photo Album: http://www.delica.ca/Photos/
Vehicle: Delica L400 LWB 3.0 V6
Location: Vancouver Island

Re: 1998 S2 L400 V6 3.0 6G72 Not starting, mystery! HELP

Post by Gandalf »

I bought an Innova OBD2 scanning tool, model 3100, and it is unable to establish communication at the port, ignition in the ON position... going to try and clean the port and check for obvious wiring issues there.
??wow?? ... really not catching any breaks.
Gandalf
Posts: 28
Joined: Sat Jun 25, 2016 4:56 am
Member's Photo Album: http://www.delica.ca/Photos/
Vehicle: Delica L400 LWB 3.0 V6
Location: Vancouver Island

Re: 1998 S2 L400 V6 3.0 6G72 Not starting, mystery! HELP

Post by Gandalf »

Scanner cannot do JOBD. Returned.

Ok, latest update.
Picked up a new timing light, my old one seemed to have inconsistencies, the pickup seemed to have trouble, found a crack in the pickup. New one is consistent.
But that only deepens the mystery.
Because the laboured cranking is very hard on the starter, cranking ease and consistency is restored if either fuel or timing is missing.
So, if I disable the spark by unplugging the 3-wire plug from the ignition control module (power transistor unit), cranking is easy, smooth & fast.
If I disable fuel by unplugging the fuel pump relay (this takes several seconds of cranking to clear all the fuel out of the cylinders) the cranking also becomes easy and smooth & fast. The laboured cranking is due to partial combustion and really bad timing or spark pattern or both.

It seems much easier to check timing with the fuel pump relay disconnected, I feel bad for the starter otherwise, and the power draw weakens the spark because the starter struggles. But regardless, I cannot see the timing mark at all when timing light is hooked up to cyl 2/5. The white mark is clearly visible on the main pulley, so I should be able to see it. In fact, I cannot see the timing mark at all with timing light hooked to ANY plug wire.

At the master cylinder/brake booster, I only have two check connectors: a black one (blue-black wire) for the fuel pump check which works perfectly when 12v applied, and a blue connector with a white/black wire, which I believe should be the timing check connector. Regardless, I cannot see the timing mark at all whether this check connector is grounded or not.

And, the strange sparking (unequal spark patterns on all 3 coils) continues.
- coil B (center) is a slow blink, perhaps once per second
- coil A (to the right as looking into the engine bay) fires twice as fast.
- coil C (the coil to the left) fires 3 times in the same amount of time, in a rhythm though, b-blink blink, b-blink blink, b-blink blink, etc

And it does all the above no matter if I swap ecus. Or swap coils, or wiring to the coils. Or ignition control module.
Swapped out the cam sensor, just in case, no difference.

When the van magically began run perfectly for two days in the middle of all this (several weeks ago), the timing looked normal, visible above the timing marker plate clockwise a ways (without the check connector grounded). So how can a mechanical timing issue go wrong, perfectly right itself, then go completely wrong again? Combined with the unicorn sparking pattern, it seems to point to an ecu-controlled spark-timing issue.
What would be the sensors or parameters that influence ignition timing? Does the ecu think the temperature is -400F?
- coolant temp sensor
- IAT sensor
- MAP
- ?

So it almost seems if something is very significantly altering the timing. Perhaps something is shorting somewhere that has a drastic effect on the ecu's treatment of timing, making it freak out.
Just for due diligence I am going to verify tomorrow if my harmonic balancer has slipped on its rubber, compare the location of the timing mark to the location of the keyway. Timing mark should be just shy of 90-degrees counterclockwise from the keyway... not that that would actually change timing, but it would change the appearance of it. I'll also look to see if the cam timing mark lines up with the crank one.
Gandalf
Posts: 28
Joined: Sat Jun 25, 2016 4:56 am
Member's Photo Album: http://www.delica.ca/Photos/
Vehicle: Delica L400 LWB 3.0 V6
Location: Vancouver Island

Re: 1998 S2 L400 V6 3.0 6G72 Not starting, mystery! HELP

Post by Gandalf »

Verified that the main crank pulley and harmonic balancer are fine, the mechanical aspects of timing appear perfect, the main pulley and right cam sprocket timing marks are perfect. Belt seems due for a change soon, but cannot see any reason to believe that these are the cause, or that internal engine damage may have occurred (timing off = mashed valves etc) to cause what is happening. The cam and crank signal plates are in their respective positions as to the square wave patterns indicated in the 1998 Montero manual (p 253). At TDC marks aligned, the large tooth behind the cam sprocket is about to trigger the cam sensor.
Gandalf
Posts: 28
Joined: Sat Jun 25, 2016 4:56 am
Member's Photo Album: http://www.delica.ca/Photos/
Vehicle: Delica L400 LWB 3.0 V6
Location: Vancouver Island

Re: 1998 S2 L400 V6 3.0 6G72 Not starting, mystery! HELP

Post by Gandalf »

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 (which should be 2x per cam rev and 1x per crank rev)
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).
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lrp374
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Re: 1998 S2 L400 V6 3.0 6G72 Not starting, mystery! HELP

Post by lrp374 »

I thought it might be time for your update. I've been following your post. I like the way you've described your problems and the solutions you've tried. You are one persistent dude! Someone on the site should be able to give you ideas - I have a diesel L300 so my knowledge would be pretty useless. Good luck, keep @ it. You are an inspiration.
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