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Discussion Starter #1
any ideas why the firing order on s 92 stealth dohc would not match the manual . We bought the car not running did a rebuild on the motor and we had a bad miss . checked for vacume leaks .swapped ecu's. mass air sensor . Then started pulling spark plug wires and found that no 1 only fires when plugged into 5 and and 2 fires swapped with 4 and the car smooths out, also changed the cas with one i picked up at jdm . Strange to me but maybe starting to overthink the problem
 

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if you are not getting spark on one of the terminals You have a bad coil, wiring problem, or dying PTU.

See if there is a local junkyard with a 3000GT you can pull a coilpack and ptu off of, all years are the same i believe for those two parts..

or see if there is a local 3/S facebook group for your area.
 

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Discussion Starter #3
also picked up the ptu when i bought the cas and we have new coils and wires and also changed the tps and have 3 ecu's to choose from and no change . Lots of hands in this car before we got it . Thankyou for your help
 

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it is more then likely in the harness then if you are positive it is a spark issue and not a injector issue. I know it seems obvious but did you replace your spark plugs and wires just to be sure it wasn't that simple? sometimes too there is a problem with the boot not actually seating correctly and not making proper contact with the spark plug.

My first VR-4 had a dead miss problem and eventually i traced it to a problem in the wiring harness.

the Service Manual should have in detail on how to check the ignition harness with a multimeter. you can download them for free from here. https://www.3sx.com/tech-manuals-service-technical-reference
 

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Discussion Starter #5
thanks for you help , if the cas is 180 out would that affect the firing order or just the injector timing
 

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It functions as both the Crank and cam, so I imagine both. So yes.

If the CAS "Puck" thing was 180 out, it would not run, and backfire, and stumble, and cough.

It should be as easy as... turn the engine to TDC, mark the position of the "Puck" thing and pop it off. The housing should have 2 dots, and the "Impeller" looking thing should have a dot on it.

They should be lined up when you take it off.

If the engine is at Top Dead Center, you can safely remove the timing covers and start right there.

However.. it seems that missfires are become a problem on these forums...
 

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Discussion Starter #7
Just seems wierd that #1 was dead . You pulled the wire and no change in the motor , swapped it with #5 and #1 fires , complex car . unless the previous owners . who knows how many have the harness wires to the coils wrong. I did a quick check and it looks like the pulled it from another car , wire colors dont match the harness
 

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Someone swapped wires in a connector. it's signaling the 1-4 coil when it should be the 2-5 coil, and vice versa. Going to be at the ECU, one of the PTU connectors, or the coil connector.
 

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Discussion Starter #10
tried to download the pdf for the electrical for 91-92 stealth and I cant scroll down through the pages it just keeps jumping to page 1 . Iam looking for ptu harness wiring diagram to see if wires were switched around . Thanks for any help , giving the download another try
 
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