No spark from 1-4 coil

[TealTalon]

Little background. This is a 91 AWD I am trying to put back together. It was stripped to be a race car by someone else, and I bought it from them and started putting it back together to drive around and play with.

I am getting no spark on 1 and 4.

I have replaced the CAS, Coils, 3 power transistors, and ECU.

The ECU came from my laser, the 3rd power transisitor is from the laser as well. Known good.

The Cas seems to be working. I have continuity on the wires that run back to the ECU on pin 21 and 22. It fires the injectors when spun by hand.

I have continuity on pins 54 and 55 from the ECU up to the PT.

I have good connection from the PT to the coil trigger wires through the harness.

Voltage on the pins at the PT connector. Pin 2 gets nothing while spinning the CAS. Pin 6 gets brief 12v pulses when spinning the CAS. I traced those back to pins 54 and 55 at the ecu.

The ECU doesn't seem to send out a signal to fire on pin 54 as far as I can tell. This is where I get lost.

The car will barely run on 2 cyl. It does not get a tach reading on the dash while running, if that helps any.

This car was pretty stripped down, but the wiring harness was untouched. It's very possible something is not plugged in, but I am pretty sure that the CAS, PT, and ECU are the only things invloved in spark signal.

Any and all ideas welcome, because I'm fresh out them. Paging luv2rallye electrical and spark issue guru.

 

[luv2rallye]

1) I assume the entire wiring harness is the stock 91 since you say it's untouched?
2) Are you replacing the "racing" engine with a stock 91? If not what year/make/mods is the engine?
3) The 6 pin PT on the 90 is incompatible with the 8 pin PT on the 91-94. So what are you doing about that? On the 91 PT, pin 7 (yellow) goes to ECU pin 54 (and pin 2 yellow/red goes to ECU pin 55). Also the 90 PT can only be used with the 90 coil (and vice versa).
4) Know that the 90 vs 91-94 ECU's have pins 6 and 14 swapped (although that shouldn't affect ignition).
5) The 91 tach will not work with a 90 PT and/or a 90 coil.

 

[TealTalon]

1) I assume the entire wiring harness is the stock 91 since you say it's untouched?
2) Are you replacing the "racing" engine with a stock 91? If not what year/make/mods is the engine?
3) The 6 pin PT on the 90 is incompatible with the 8 pin PT on the 91-94. So what are you doing about that? On the 91 PT, pin 7 (yellow) goes to ECU pin 54 (and pin 2 yellow/red goes to ECU pin 55). Also the 90 PT can only be used with the 90 coil (and vice versa).
4) Know that the 90 vs 91-94 ECU's have pins 6 and 14 swapped (although that shouldn't affect ignition).
5) The 91 tach will not work with a 90 PT and/or a 90 coil.

1) Yes.
2) It didn't come with and engine just a shell. So everything is put together with odds and ends. It's a 6 bolt engine. Stock block nothing special.
3)Everything in the 90 Laser is out of a 91 FWD Talon, so I believe what I have to test with is all 91+, but how can I tell the two PT's apart?
4)Yup, but it's all 91 as far as I know.
5) I suspect an incorrect PT now, but I have never owned a 90 so i don't know where 90 stuff could have come from.

 

[luv2rallye]

Everything in the 90 Laser is out of a 91 FWD Talon, so I believe what I have to test with is all 91+, but how can I tell the two PT's apart?

Answer: The 90 PT has a 6 pin connector, the 91-94 has an 8 pin.

1) You said (PT) "pin 6 gets brief 12v pulses when spinning the CAS". Pin 6 is +12V ignition switch on. Did you mean pin 7? What color wire? Describe these 12V pulses more.

2) I know you think the PT is at fault but please do this test anyway. Test for a signal going to the coil pack by plugging a test light (or small 12V bulb) into the coil harness plug connector (unplug it). Plug one test light wire to the black/white (black with white stripe) wire pin and the other to the yellow/green pin. Crank the engine. You should see the light blink. If it doesn't, then you'll know the problem is before this point like the PT or ecu or wiring. If the light blinks and there was no spark at the plugs, you have a bad coil or plug wires. Now move the yellow/green to the yellow/black and repeat.

3) If the light didn't blink on one of the coil wires, test the PT like this: http://www.dsmtuners.com/forums/showthread.php?t=229419

4) If PT test passes, measure both the dc and ac voltage on PT pin2 (yellow/red) and pin 7 (yellow) all while both cranking and not cranking but key to On. Note these voltages may only be 0.8V or less especially while cranking.

 

[TealTalon]

1) I as wrong on the pin number it a 7 pin , 6 wire connector. 4 is empty so I mis labelled it. If I remove the PT and check voltage on pin 7 it's none or very low, when I spin the CAS by hand I see the voltage spike up to 12v I assume this is the trigger signal.

2)Yellow green flashes the light. Yellow black does not.

3) I'll test, but I doubt I have 3 bad PT's. The last one I tried was from a known running car. I think I'm at the point where I have eliminated the coil and PT.

4) .041 on both wires without cranking with the multimeter set to DC 2. I'll have to get a friend over for cranking tests.


It's definatetly 91 stuff. 7 wires 8 pins on the PT connector. 7 Pins with a blank spot on the PT itself.

 

[luv2rallye]

1) I as wrong on the pin number it a 7 pin , 6 wire connector. 4 is empty so I mis labelled it. If I remove the PT and check voltage on pin 7 it's none or very low, when I spin the CAS by hand I see the voltage spike up to 12v I assume this is the trigger signal.

2)Yellow green flashes the light. Yellow black does not.

3) I'll test, but I doubt I have 3 bad PT's. The last one I tried was from a known running car. I think I'm at the point where I have eliminated the coil and PT.

4) .041 on both wires without cranking with the multimeter set to DC 2. I'll have to get a friend over for cranking tests.


It's definatetly 91 stuff. 7 wires 8 pins on the PT connector. 7 Pins with a blank spot on the PT itself.

Per above:
(Note: All voltages are measured to ground)

1) Ok let's get our pin numbers straight. It's a 8 pin connector (not 7) with 7 wires (not 6) as you state at bottom of previous post. And pin 5 is blank (not 4). Pin numbering starts with the yellow/black as pin 1 and yellow/green as pin 8. This is the correct pin numbering and we must both use it if we are to communicate together. It helps to always state the wire color as well as the pin number so please do so. This aids as a double check as well as the wire color is far easier to see/figure out than pin numbers since you never know without the diagrams the connector pin numbering orientation.

What happens when you remove the PT and measure pin 2 (yellow/red) voltage and spin CAS? If you get nothing, the ECU, CAS, or wiring between all these is faulty.

3) I just also want to make sure nothing is burning out the PT's.

4) Leave the PT plugged in for these tests. Get at wire through back of connector or stick a safety pin through wire insulation. Don't be surprised if voltage never goes over 5V at any time. If you get nothing or very low on one, the ECU, CAS, or wiring between all these is faulty.

5) Test the CAS per: http://www.dsmtuners.com/forums/showthread.php?t=238267#post50470620

6) If the CAS and everything check out, I'd still suspect the ECU. Try swapping with a 91-94, not a 90. If nothing wrong inside perhaps the connector isn't making contact or one of the pins going inside the ECU from the connector has a bad circuit board connection.

 

[MountainDew]

I had the same problem on my 2g. Ended up being my CAS. Swapped a 1g one and it fired right up.

I'd try a different CAS. Just make sure the alignment marks are correct and the motor is TDC. I'm sure you already knew this though.

 

[TealTalon]

Just wanted to post the solution to my problem.

I had a friend come over to help trace the electrical issues.

Turned out to be the pin inside the CAS connector for the white wire. The spade was spread out and not making contact with the pin on the CAS. How I was missing that is beyond me. We just started all over troubleshooting and found it pretty quickly.

Does anyone sell a replacement CAS plug? Every single one I see in the junk yard is just as brittle and falling apart as the next.

Runs like a champ. On to the next list of problems.

Thanks for the help.

 

[MountainDew]

Just wanted to post the solution to my problem.

I had a friend come over to help trace the electrical issues.

Turned out to be the pin inside the CAS connector for the white wire. The spade was spread out and not making contact with the pin on the CAS. How I was missing that is beyond me. We just started all over troubleshooting and found it pretty quickly.

Does anyone sell a replacement CAS plug? Every single one I see in the junk yard is just as brittle and falling apart as the next.

Runs like a champ. On to the next list of problems.

Thanks for the help.

I have a CAS plug I could sell you. Still has the little pin thingy on it as well. PM me if you want/need it.