Need help with spark problem please

[greasemonkey25]

First off: The car is a '90 TSi AWD M/T. Still stock for now, though if I can get it running again, I plan to modify it. Well, to make a long story short, I had a little adventure a few months ago. The key on the crankshaft sprocket broke, and needless to say, my car got a little out of time.

Several months later, after running into some more problems, I now have a newly rebuilt head, a new ECM, new coil pack, and new ignition module (or power transistor unit if you prefer). I had just changed the plugs and wires just before this happened, and they are still good. I have also replaced the CAS since the "incident." I have good compression, fuel, timing, etc...and I have spark on cylindars 2&3 only. Now, I am a mechanic, and I work in a mechanic shop with other mechanics, who are just as fuddled as I am. Has anyone ever encountered this problem before? I couldn't find any threads with this specific problem, and I can't think of any other place to ask this.

Surely SOMEONE has to have run into this before...

 

[luv2rallye]

First of all the coil pack, ecu, and power transistor unit MUST BE for a 1990 as that year was different than all other years (see http://www.ecanfix.com/~mdhamilton/1990schematics.html). If you don't that's your problem. If you do, since cyl 1&4 don't fire, it can only be the cyl 1&4 coil, or cyl 1&4 power transistor, or the ecu, or the wiring between any of these. There isn't anything else. Since you say you got all these components "new" (although I've seen faulty "new" components), you should probably check the ignition wiring for opens and shorts (there's only 3 wires to test).

 

[greasemonkey25]

Yes, I know that these parts are '90 only. They all check out good, and I wouldn't be much of a mechanic if my car didn't run for six months and I still hadn't checked the wiring. Trust me, if this was something simple, there would be absolutely no need for me to post a thread on it.

If I can't get this thing fixed pretty soon, I am going to have to part it out or something, because I am tired of looking at it every day. (It is sitting behind the shop where I work.) So, if anyone wants some good used parts (this term being used rather loosly, as some of them have 0 miles on them), please e-mail me, because this is looking more and more like my only option. I honestly think this car doesn't WANT to be fixed...

 

[kottyking]

So its not throwing any codes?

 

[luv2rallye]

Well you certainly have a tough one all right. Ok how about this (I'm looking at 91 ignition schematics and am assuming 90 is the same).

(1) There is a 1 pin engine speed adjustment connector (white/black wire) that connects between the ignition coil 1&4 primary and the power transistor for 1&4. If this was partially shorted or connected to something it would prevent 1&4 from firing. Unplug the coil and measure resistance from it's harness side connector pin 2 (yellow/green wire) to both ground and +12V battery post. It should be near infinite on both (as should pin 1 yellow/black wire). If not, unplug the power transistor unit and measure again.

(2) Do you get normal spark intensity on plugs 2&3? And absolutely nothing on 1&4 right? Did you try (with ignition switch on, engine not running) forcing the 1&4 coil to fire by touching it's pin 2 (yellow/green) briefly to ground? If this works next touch a 1.5V cell battery positive (ground it's negative) to pin 7 of the power transistor connector (yellow wire). This should again fire 1&4 using the power transistor. Keep all connectors plugged in when you do these tests. To get on the wires either insert a probe into the connector pins from the wire end or insert a safety pin through their insulation. If this works next check pin 7 of the power transistor unit with a scope while cranking to see if the ECU is providing pulses. If not check if that wires pin on the ECU connector is locked (not being pushed back) when the connector is pushed on.

 

[greasemonkey25]

Man, I wish I had a scope

I'll try that, though I'll have to look at my wiring diagrams and figure out what wire that is on a 90 (5 wires to power transistor harness). Is this one of those "if everything's working, this should work" things?

And no, no codes from computer. The car hasn't ran since I put that ecm in, and anyways, I disconnected the battery when we pushed it back outside about a month ago. Seriously, anyone want a good parts car?

 

[luv2rallye]

Man, I wish I had a scope

And you call yourselves mechanics in a shop with no scope? (just teasing)
Well you should be able to measure the voltage (both dc and ac) on the yellow wire (cyl 1&4) of the transistor unit and compare it to the yellow/red one (cyl 2&3) while the engine is cranking. Even though they are very narrow positive pulses from the ECU, your meter will read some average (should not be zero) and they should be the about the same. To give you an idea on my '99 I have 0.4vdc and 0.8vac at idle on the comparable wires.
Here's some 90 wiring diagrams:
http://www.ecanfix.com/users/mdhamilton/ingnitioncompare.html
http://www.ecanfix.com/users/mdhamilton/images/1990ignition/1990schematic.jpg

Your sure no one did the 91+ to 90 ignition conversion thing? Some wires get changed in the harnesses and the filter capacitor is different.
http://www.ecanfix.com/users/mdhamilton/ecuconversion.html
or http://www.dsmchips.com/1990ecu.html

 

[greasemonkey25]

Well, according to the wiring diagrams I have (out of my Haynes manual), the wiring is all '90. Do you think that swapping the whole system with a '91-'94 system would help? I have also checked our wiring diagrams at work (we have Mitchell1 on the computer there), and they tell the same story. However, I do have enough experience with repairing cars to know that books can lie to you...

I have also thought about replacing the entire system with an aftermarket one. I have seen some that have a seperate coil for each cylindar, but they're quite expensive for just a "test." Do you think that might help, or would I just be wasting money? I know I have no need for a high output ignition system unless it would help to solve my problem.

I have checked VDC on the wires to check for signal, but I have not checked for ignition pulse yet. I will do so tomorrow if I have the time (likely the way this week is going). I have also checked for continuity on all the wires on the coil and the transistor unit, and had ro rerun a ground wire. I have changed the transitor unit since then (I think it fried), but I'm not sure I'm getting decent parts here in Podunk, MO. I have now bought one used unit off the guy who used to own this car (and has several others), but that didn't work. I then bought a Borg-Warner unit, and traded it in seven times hoping to get one that will magically make the car start. Funny thing, though...come to think of it, when this all started, I only had fire on 1&4. I really think that if I could get my hands on some worthwhile parts my problem would be solved. Is there a better brand out there? Are there any parts for this thing anywhere that are worth the small fortune everyone seems to want for them?

 

[luv2rallye]

Sounds like you better test the coils and transistor unit out of the car (see manual for proceedure) before proceeding with anything to see where you stand. Since you said no spark happened after you changed the ECU, that is why I thought perhaps the system/harness was converted or pins on the ECU connector may have gotten pushed back (not locked). You also need to measure those transistor unit voltages to know what to do next. If all else fails, you can always do the 91-94 conversion but I would feel more comfortable figuring out why the present setup doesn't work just in case some harness wire was changed so any new system wouldn't work either (and you wouldn't know why).

 

[greasemonkey25]

Small correction: No spark problem started in August of last year, and is the root cause of all my woes. I think I'm just going to sell the stupid thing to someone who needs the parts. Thank you for your help, Luv2rallye

 

[papifry]

Ok... hope this helps...
My buddy just bought a 95 GST and like a day later ha calls ma and says he's stranded... car wont start at all. I show up where he is stuck on the sid of the road, and start trouble shooting by first checking all of his connections. his power transistor somehow came unpluged while he was driving down the road... which obviously killed it and stranded his ass... so I plug it back in and it starts, and I follow him back to his house, where we zip tie that bastard on... less than 30 minutes later, he cranks it again and it idles fine, and as he is backing out of his driveway, it starts idling like crap and his RPM guage stops working...
troubleshooding once again, I find that when I pop the plugwires off, only the first and the fourth ark off the valve cover. Since I am now running a COP setup, I swap out his coil pack for my old 91 coilpack...no change... so I then take the power transistor off my 91 and swap it onto his 95 and wahla... spark on all 4 and the guage works...
Im not sure why, but unplugging the transistor while the engine is running messes that thing up.

 

[greasemonkey25]

OK everyone, thanks a lot. Really. But I'm not even trying to fix the car anymore. And as my first post (or maybe the second one) states, I have been through about eight power transistors in that thing with absolutely no change at all. I have moved now, back to where the car came from, so the guy that built it now has it at his shop and I'm going to let it ness with his head for a while

 

[92TurboClipse]

Hi,
When the key broke on the crankshaft, what kind of damage did it cause. How much did it cost you to replace the key..... I am have the same problem with my '92 6bolt.
Later
Chris