Mitsubishi 6G72, one coil firing only, new install

[ravensierra]

Hi, I'm looking for a bit of assistance with a problem I'm having with my install of MS3/MS3X if possible.

The car is a Mitsubishi GTO with a 6G72 V6 twin turbo engine, running wasted spark ignition. Firing order is 1-2-3-4-5-6, coil A fires 1/4, coil B fires 2/5 and coil C fires 3/6.

I'm using the spkA/B/C outputs from the MS3X card, wired to the OEM PTU (power transistor unit) to drive the coils. The PTU takes a logic high signal, and is working fine with the stock ECU. I am working with an adapter harness I soldered together to retain the stock engine wiring loom, and have verified that I have the spark outputs soldered correctly and have continuity in the harness for all 3.

Now here is my problem: using the spark output test in TunerStudio, coil C is firing as expected, but I am getting no activity whatsoever from A or B. I'm not sure what troubleshooting steps to take next, I have tried dwell up to 8.0ms to try to get the other coils to fire but that is not the problem. I assembled the MS myself.. Do the MS3X outputs use transistors on the mainboard at all?

My msq is attached, any help appreciated

[elutionsdesign]

No, nothing on the mainboard, its all on the MS3X card. Lacking a scope I'd just start checking the coil outputs while in test mode with a DVM.

[ravensierra]

No, nothing on the mainboard, its all on the MS3X card. Lacking a scope I'd just start checking the coil outputs while in test mode with a DVM.

Should I disconnect the coils and run huge dwell to do the test?

[jsmcortina]

First off I'd leave them connected and use normal dwell - see if they spark that way.

Certainly disconnect them if you are going to run large dwell.

James

[ravensierra]

First off I'd leave them connected and use normal dwell - see if they spark that way.

Certainly disconnect them if you are going to run large dwell.

James

So I ran some further tests on the MS3X. My DMM didn't have the resolution to pick anything up with standard dwell, so I ran output test mode with 25.5ms dwell and 50ms interval to give ~50% duty cycle.

With these settings the SpkC pin measured @ 2.50-2.51V, indicating 5V during the pulse. SpkA and SpkB both measured at 0.69-0.70V, indicating around 1.4V? Am I looking at failed driver circuits on the MS3X? And what would be the cause of failure if so?

(Does my .msq look alright? I've triple checked it for configuration errors as far as ignition goes)

EDIT: my firmware version is 1.3.2

Thanks,

Jack

[elutionsdesign]

Nothing in your tune file jumps out as wrong, can you post up a composite cranking log? If you're loosing sync it could do what you're seeing.

[ravensierra]

Nothing in your tune file jumps out as wrong, can you post up a composite cranking log? If you're loosing sync it could do what you're seeing.

Just to clarify, it's not outputting 5V even in the testmode. I have got solid rpm though, needless to say it doesn't run on 2. If you really want the composite log I will get one tonight

[elutionsdesign]

Yeah, good point. It certainly points to a bad 3X card.

[ravensierra]

Yeah, good point. It certainly points to a bad 3X card.

How do I determine bad MS3X card vs. main CPU on the MS3? Because those outputs come clear off the processor correct? And what do I do, buy another card basically?

[ashford]

another thing to try is set it for wasted cop then try out outputs d, e and f(should be the same as a b c) another thing(probably first) to try is connect output c to coil 1/4 2/5 and see if it runs those 2 channels.

and no the ms3x card is not wired directly to the processor, ther is a small ic to run the outputs
http://www.msextra.com/doc/general/ms3v ... .html#ms3x

[ravensierra]

another thing to try is set it for wasted cop then try out outputs d, e and f(should be the same as a b c) another thing(probably first) to try is connect output c to coil 1/4 2/5 and see if it runs those 2 channels.

and no the ms3x card is not wired directly to the processor, ther is a small ic to run the outputs
http://www.msextra.com/doc/general/ms3v ... .html#ms3x

Ah I see, is that chip 5V in, 5V out?

Thanks for everyone's help so far by the way

[jsmcortina]

Ah I see, is that chip 5V in, 5V out?

Yes.

James

[ravensierra]

Alriiight. So I have found the problem. Pins Y6 and Y7 (SpkA and SpkB outputs) on U13 are bridged between the pins. All 8 inputs on U13 get 5V from the CPU, and C through H output 5V.

Should I carefully debridge the 2 pins or is U13 toast? Or should I contact DIYautotune before I go knifing around?

[racingmini_mtl]

Contact DIYAutotune before doing anything. And a knife is not the way to remove solder bridges.

Jean

[ravensierra]

I received a replacement MS3X card from DIYAutoTune (exemplary service from Matt, thanks) and have all my coils firing as expected.

I've got another problem now however: my RPM signal which was so perfect before is nowhere to be seen. Of course I checked all the jumpers on the new 3X card before I installed it and it does have the JP7 pullup for the optical cam sensor.

I have fiddled with the pots on the MS3X card (and the mainboard later) to no avail, and the composite logs in TunerStudio seem to be blank unless I'm doing something wrong.

The only difference I can think of is that the JP3 jumper is installed on the replacement card. I can't exactly see how this would pose an issue but it's a possibility?

Is someone please able to help me out with some troubleshooting steps? I know there's probably dozens of threads with issues like this, sorry.

I don't own an oscilloscope, I have got the basic JimStim though. It will be a challenge to get it down in there to test, the MS is INSTALLED i.e. buried in the dash, and it's a bit of a pain to run a jumper from the 2nd tach output up to the MS3X card for the cam signal.

Any help would be more than appreciated, I'm so close and can't wait to fire it up on the MS. (Still works on factory ECU btw)

Can provide composite logs etc as requested

[Matt Cramer]

Can provide composite logs etc as requested

Please do. I'll take a look.

Also, is JP7 in place?

[ravensierra]

Can provide composite logs etc as requested

Please do. I'll take a look.

Also, is JP7 in place?

Thanks Matt that would be great, sorry it took so long to post.

Yep JP7 is in place and got 5V pullup on the V3.0 VR input.

I have attached a composite log of two cranking runs, the second one in the file is a bit longer.

The CAS is a cam-mounted optical sensor like this:



6 slots on outer ring for crank angle, 4 slots on inner for cam.

Of note is my battery voltage drops to 9.4V during cranking, not sure if this is too low for MS. The fuel pump primes after I release the key from the ST position too.

Jack

[Matt Cramer]

That's got a signal on both sides - try swapping your Ignition Input Capture setting.

[ravensierra]

That's got a signal on both sides - try swapping your Ignition Input Capture setting.

I'm in business, thanks Matt.

I just looked at the msq I posted when I started this thread, and rising edge was the setting I had then, and the one that finally gave me rpm from the cas...

The 6G72 wheel simulator on the JimStim needs falling edge set to register rpm for whatever reason, trap for young players ;-)

thanks again