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Discussion Starter #1 (Edited)
STILL NO Spark PROBLEM: Please help!

I have a 93 VR-4.

Upon getting it ready to do the 60k and take out the first time this spring I ran into spark problems. Ok, first off... the car has been running fine. I had it running in the driveway for 10-15min., then shut it down, came back an hr later to move it into the garage, upon starting it was only running on 4 cylinders!

I figured maybe if it sat for a day, maybe I'd get a different result... wrong, cold start still 4 cyl.

Ok, it doesn't have spark from 3 & 6. So I checked the Ignition coils primary & sec. resistance... seemed ok. then went to the ignition power transistor and checked that. Seemed ok according to the service manuals standard checks also.

So what's next? I've read alot about ECU/ECMs. I'm not sure if this is the next place to look?

I know alot of you have more experience working with these cars. So any help would be greatly appreciated!

Thanks.
Dean
 

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Hmm..

Hey,

That is strange. I'm no expert, but have you checked the simple stuff? Make sure that your Wires are good and connected. You can do so by taking off the wire from the spark plug and holding it close to/on the engine block. If you see a spark then it's firing. I dunno if the ECU would be causing it though. Sounds reasonable since it is ECI. Have you changed out your CAPS?

Later,
phaZed
 

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Discussion Starter #4
Yes, I've checked for spark... Cylinders 3 & 6 are not firing. These cylinders are also "paired" on a coil, but that coil comes back with the same readings as the other two that fire.

I have a grand prix and have replaced a coil before only to find out it was the ignition module that was bad. So I'm not sure, but the Ignition Power Transistor and the ignition module in the GP seem to be the same thing? I'll have to check the manuals in the GP to determine that.

I've had the ECU/ECM (same thing right) out after reading stuff from here about CAPS. It took me about 15min to remove, 5 min. to put back in... I didn't "see" anything really wrong in there, but did have a slight odor over the area of the CAPS. I think I'll pray that I can replace them. I'll take it into school to the Electrical & Computer Eng. workshop and find out from the tech. guy here if they have the right soldering tools to do the job. I've never messed with anything like this before from the tech/soldering standpoint.

Is it easy to do? Any special tools or things to watch for? I know it is only like $1 in parts (IF this is the only thing wrong).

Thanks.

Dean
 

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why dontr you switch coils....swap 3 and 6 coil with 1 and 5 and see if ignition problem stays with 3 and 6 cly....if so its good chance its the power transister as I had this prob a few ago...
 

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Discussion Starter #6
Thanks... I'll try that tomorrow after work...getting too late tonight.

Do you know how much the power transistor ran?

I haven't checked into cost yet. Checked at school for a decent solder equip in case I need to do the CAPS.
 

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Discussion Starter #7
Ok, I did the coil swap. The problem stayed with cyl 3 & 6, so it isn't the coil. Also the car will not start now. I was looking at the manuals under page 13A-158 (Ignition coil & Ign. Power Transistor) I noticed an (Ignition timing adjustment connector) in the ckt diagram coming from the ECM pin 104. Where is this thing located the I.T.A.C. and what does it exactly do?

In the meantime, I'm going to have a pizza then go back out and measure/check voltage between the ignition power trans. and check for open ckt between the transistor and the coil, etc. like the book says.

This is a pain in the ass! I'm getting anxious to take the car out since my insurance comes back on in May and hopefully it'll stop snowing!

Thanks for the help guys!
 

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Discussion Starter #8
Ok, followed pages 13A-160,161 in the manual, along with page 16-32 in the electrical book, and got to step 6, measuring the voltage of the control signal circuit of the ignition power transistor.

Here's the result:
connector #3 4V+
concector #2 4V+
connector #1 ~none/some stray voltage

So I went back and checked for continuity on the cable from connector #1 to pin 11 on the ECM. It's ok.

So I think this leads me to work on the ECM. Hopefully, replacing the caps will solve the problem! The car went from running to dumping 2 cylinders, to not wanting to start at all...all within about 2-3 key turns! So "uncle sam's" tax return hopefully won't be going to Mitsu for a new ECM... praying for just <$5 for caps.

Anyone have any other thoughts or ideas? I'm taking the ECM into the "radio shop" at work to use all the tools to test/replace the caps and hopefully i can pick some up quickly somewhere this week and get it up and running.
 

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ECU Problem

Please look at previous posts on ECU problems. I had the same firing problem as you and replaced capacitors in ECU and they went away. Your due for an ECU capacitor change with a 1993 VR-4! These capacitors usually last 8 - 10 years.
 

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Discussion Starter #10
Ok, changed out the capacitors (which looked and tested ok)... Late last night got everything back together... car still won't run.

I didn't have a 2nd person to help me determine if I still had the spark problem, but I'm sure I still do since it didn't fire up.

:-(

I'm sorta at a crossroads with this....

any ideas would be appreciated... i just don't feel like dishing out $200 for this part and $200 for that, etc. etc. until I fix 1/2 dozen+ things that never needed to be fixed.

I guess tomorrow after work/class I will begin taking voltage readings off the ECM as mentioned in the Service manual to see if I've missed something there.
 

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Firing Problem

Just some thoughts before you spend more money!

1) Was something changed prior to winter storage? e.g., Did you paint coil bracket or detach coils or move something else electrical?

2) Could the coils be firing for the wrong cylinders? If the coils have been switched around or taken off bracket this can happen.

3) Condition of spark plug wires?

4) Soldering capacitors in ECU is not always easy. Do good connections exist? Are cap values correct and placed in proper place on board?

This has got to be a complex problem with an easy cheap solution especially if the car was running well prior to winter storage!
 

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Discussion Starter #12 (Edited)
Yeah.. I know...

The car was running perfectly fine... 1 HR earlier!

...and no I hadn't done any modifications, etc over the winter. I was just preparing to go to work on it for it's "early" 60k tuneup. The car has 50k miles on it, but I figured it was time.

one hr later...
....upon start-up... it was running on 4....

And about 3-4 starts later during diagnoses, won't start at all....(edit - was flooded)

Sure, I've removed coils, etc. even swapped 2 around to determine if there still might be a prob. with one...since the spark problem related to 3&6, but it stayed with those two cylinders and didn't follow the coil, also as noted above, when the key is turned on (edit - actually I think it was "cranked")I have no voltage out of pin 1 of the harness for the power transistor coming from the ECM, but 2 and 3 are fine (edit 3-4V). So this leads me to believe it is the ECM... the harness back to the ECM has continuity. GRRR>... just not gonna give up on it yet! (and purchase new/used ECM)

The caps seemed good, but I had "a professional" ;) technician from work replace them with new ones.. (just to see if it made a difference). It may be flooded now that it won't start... I'm going to pull spark plugs when I get home...just in case.
 

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Discussion Starter #13 (Edited)
Ok... yeah... when I had the problem of the car not starting... I'm sure it was flooded... I pulled the front 3 plugs to clean them off and let some evaporation take place for a day. The next day it fired up, but still on 4 cyl. this after replacing the 3 capacitors in the ECM.

I then spent last weekend diagnosing everything I could find from the service manuals that showed I could check with an oscilliscope. I found that still had a problem out of the pin 11 from the ECM!!! It was only giving out a waveform of about 20mV, and should be around 3-4 V. The other 2 pins gave out the proper signal. So now I've purchased a used ECM from another 93 VR-4, just plugged it in about an hr ago, and still no spark from the same 2 cylinders!!!

I'm really at a crossroads here!

Any more opinions on what my be causing this? I also got another power transistor from the yard and coil packs for $40!!! But I'm nearly positive they aren't it, as I've done the required checks on those also. I'll probably go out and swap that power transistor, see what spark results (pain in the ass!) But right now, I think the car is flooded again! It's not bad spark plug wires, because we have some wires to plug directly onto the coils to check for spark to the block....
 

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What does the signal level at C52 pin 11 look like with B21 disconnected at the power transistor? Your problem sounds like the coil 3-6 control transistor in the power transistor module is shorted emiter to base.
 

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Discussion Starter #16
I haven't tried that yet. (connector removed from power transistor and hooking scope to pin 11). I've taken scope readings from pin 11 while everything was connected and running on 4 cyl., result was a 20mV signal identical to pins 10 & 23 except they had about a 3-4V waveform like shown in the manual page 13A-159. As mentioned above, I've done the various "step by step" suggestions in the service manuals for testing the harness, coils, power transistor. I also thought it was my ECM, so I purchased a used one, also had them send me up another power transistor. Neither of those helped. Both my current ECM and Power transistor module and the used ones I picked up have the same results. I had did the variuos "continuity" checks mentioned for the harness... seemed ok.

my Dad just mentioned that I run another wire from the ECM to the end of the harness that plugs into the power transistor and test ea. corresponding pin with ea. on the ECM.

I got some unusual results here, gonna check again tomorrow after work to verify...

So I'm thinking I have a faulty wire harness! Unless this "new/used" ECM is also crap, but I highly doubt it would give me the same results.
 

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Riskeavr4,

Could you please enlighten me with your knowledge of the power transistor, and why you think it may have a short? Just trying to soak up some knowledge on some specifics of the power transistor, and the rest of the ignition system that I may not know. Thanks man!

Oh,... Duder,... let us know what turns up. We all hate gremlins, and the ignition system seem to be a haven for them over the past couple months.

Best of luck!
 

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O.K So you have ohmed from pin 11 at the ECM connector to pin 1 at the power transistor connector and it checked good? And ohmed pin 11 at the ECM connector to ground and its open?. Both tests with both C52 and B21 disconnected. You have replaced the coil, power transistor module and the ECM and the signal at pin1 is still always low.???????? If its not an ECM failure ,not a shorted or open wire from the ECM to the power transistor module and not a shorted power transistor I would guess the control transistor in the ECM is always on keeping the output at pin 11 low. What does you crank angle sensor output look like? Kinda guessing here but if the crank sensor output is bad relative to the 3-6 posistion the ECM control transistor wont change states and that could show this problem. Its a reach but you are running out of things to check.

As far as my earlier guess on a short E-B on the power transistor it was a guess based on how it might fail. There is a 5 volt line in the ECM on the collector of a transistor the is the output to the power transistor. The ECM is supposed to turn that transistor on/off based (somehow???) on crank sensor input. That line switching on and off turns the power transistor on and off which charges and dischargec the coil. The power transistor has ground on the emitter and if it shorted to the base it would put the control line from the ECM always low. Its late( early for most people) and I am going to sleep, long, mostly boreing night at work;)
 

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riskeavr4, Steve is it?

What do you do for a living? Seems electronics related, or you studied that area alot. Its been 9 years since I've been through analog/digital. I deal with all forms of network integration now, and havn't had to use any of my electronics background in so long, that I've forgotten most all of it. I hope to get back into it enough to be proficiant in troubleshooting automotive systems. I'm getting close, but its always nice to pick the brain of people who seem more knowledgable in specific area's. Thank you for the feedback, and I may pick your brain some time in future.


Duder,... any luck?
 
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