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Please help- engine swap, won't start- RESOLVED


GVR-4
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Galant VR-4 org Post #: 1249235 posted 06/27/20 11:42 AM     Remind Me!  Send Private Message   Edit Post      
Ok, guys. I've been trouble shooting for a week or two and can't figure out what I got wrong with the wiring.

Background: This is a 4g61t swap into a 1990 AWD Colt Vista wagon. It's 1990 turbo ECU configuration; essentially a SOHC NA to DOHC turbo swap. There were 18 conductors out of the 52 on the ECU that were different. I was very careful with the wiring, but clearly I must have gotten something wrong or missed something. Engine will turnover, but no spark. Once I have the ignition system working properly, I can see if there are any issues with the fuel system.

Below is what I know.
* ECU is good (ran my 2.3 Mirage turbo)
* coil pack is good (ran Mirage)
* PTU is good (ran Mirage)
* there is +12v power to the coil pack when ignition is in the RUN & START positions
* tried another plug wire on #3, still no spark
* no voltage change on coil pack when key is in START (verified with analog meter)
* CAS is good from bench test

There's a lot more to unpack, but I'll start here. I'm trying to go back to the fundamental question "What has to be true for the coils to fire?", but I'm stumped. If anyone has any ideas, please let me know.

Thanks.

dp



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dave Peter

Can't polish a turd.


Edited by GVR-4 (06/27/20 04:02 PM)

Posts: 2604 | From: Asheville, NC USA | Member Since: 04/22/02 | IP: (50.111.81.128) | Report this post to a Moderator

GVR-4
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Galant VR-4 org Post #: 1249236 posted 06/27/20 11:56 AM     Remind Me!  Send Private Message   Edit Post      
Injector resistor pack is known to be good too. That's related to fuel, but confirmed to be true nonetheless.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dave Peter

Can't polish a turd.

Posts: 2604 | From: Asheville, NC USA | Member Since: 04/22/02 | IP: (50.111.81.128) | Report this post to a Moderator

transparentdsm
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Galant VR-4 org Post #: 1249237 posted 06/27/20 01:09 PM     Remind Me!  Send Private Message   Edit Post      
Uncover the wiring harness for the PTU, I was just working on a 90 tsi that had no spark and it ended up being a bunch of old, brittle and splintered wiring.


Edit, I also replaced the harness with a 91+ PTU harness and 91+ PTU as my wires were all broken to close to the plug to repair and I couldn't find a 90 harness locally. Very simple to add the harness.



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Edited by transparentdsm (06/27/20 01:12 PM)

Posts: 3651 | From: Klamath Falls, Or | Member Since: 07/27/11 | IP: (71.89.204.234) | Report this post to a Moderator

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Galant VR-4 org Post #: 1249238 posted 06/27/20 01:27 PM     Remind Me!  Send Private Message   Edit Post      
Thanks for the response. I've uncovered almost all of the wiring in the engine bay, so I'll go confirm the condition of the PTU wires is good. I have two '90 PTU's (both ran the Mirage engine) and two 91+ PTU's (unconfirmed to be working properly) and a 91+ PTU harness on hand. I agree the 91+ is better with the plastic clip rather than the metal retainer clip (like the fuel injectors). I've read how to use the 91+ on a 90, so that may be an option.

I'm also going to check that I get ~5v at pins 21 & 22 for the CAS output back to the ECU.

Thanks.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dave Peter

Can't polish a turd.

Posts: 2604 | From: Asheville, NC USA | Member Since: 04/22/02 | IP: (50.111.81.128) | Report this post to a Moderator

GVR-4
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Galant VR-4 org Post #: 1249239 posted 06/27/20 02:34 PM     Remind Me!  Send Private Message   Edit Post      
Wiring for the PTU is in good shape. Even the rubber boot is still pliable. I may try to figure out if the trigger wires at pins 2 & 6 of the PTU are getting the signal from pins 54 & 55 of the ECU like they are supposed to during cranking.

Pins 21 & 22 are getting the voltage changes as they are supposed to when the CAS is rotated manually.

I did discover I have a bad connection at pin 24 (common with pin 17) at the ECU. At least I think. I jumped it to pin 17 for the '90 turbo wiring requirements. It would energize the fuel pump when I moved it. Although looking at the wiring diagram, I'm not sure how the sensor ground would affect the fuel pump being energized at this point. I'll verify I can reproduce the occurrence and, if I can, I'll repair it.

What a puzzle.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dave Peter

Can't polish a turd.

Posts: 2604 | From: Asheville, NC USA | Member Since: 04/22/02 | IP: (50.111.81.128) | Report this post to a Moderator

transparentdsm
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Galant VR-4 org Post #: 1249240 posted 06/27/20 03:00 PM     Remind Me!  Send Private Message   Edit Post      
did you pull the rubber boot back? mine was soft as well, but from how it is bent and positioned from the factory it had broken wires under the boot. from my experience you have 3 options if your not getting spark. coil pack/harness, PTU/harness or the ECU is bad.



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Posts: 3651 | From: Klamath Falls, Or | Member Since: 07/27/11 | IP: (71.89.204.234) | Report this post to a Moderator

GVR-4
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Galant VR-4 org Post #: 1249241 posted 06/27/20 04:01 PM     Remind Me!  Send Private Message   Edit Post      
IT'S ALIVE!!

It seems that there was at least one bad connection at the ECU. Likely as a result of me sticking the tip of the Fluke probes into the connector. I used a jeweler's screwdriver to press them all back where they should be and I got a spark. I put the plug back in and it fired up. Man, what a relief after struggling so long. I set the base timing and shut it off. Now to button everything up, while making sure it starts and runs consistently.

Thanks for the input, Shane. Very much appreciate your experience and feedback. I didn't pull the boot back, but if I still have problems, I will check the conductors at the plug.

I still come back to this board when I'm stuck. Great community & knowledge base.

Thanks.

dp



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dave Peter

Can't polish a turd.

Posts: 2604 | From: Asheville, NC USA | Member Since: 04/22/02 | IP: (50.111.81.128) | Report this post to a Moderator

transparentdsm
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Galant VR-4 org Post #: 1249242 posted 06/27/20 04:53 PM     Remind Me!  Send Private Message   Edit Post   
glad to hear its running. its always a great feeling of victory when you figure something out. i had a similar issue with a volvo i worked on except it would run till it got warm and then shut off. turned out one of the CAS sensors wasnt fully seated. pushed it down a little, heard a click noise and the customer was back on the road.



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Edited by transparentdsm (07/02/20 07:07 PM)

Posts: 3651 | From: Klamath Falls, Or | Member Since: 07/27/11 | IP: (71.89.204.234) | Report this post to a Moderator


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