Ok well I am running out of ideas here. I am starting to question the ecu and wiring harness, not to mention every electrical aspect of the car.

The issue is that I have no spark, no working tach, and I still need to check to see if the injectors are firing. I have tried replacing the CAS and testing the in car one per FSM, and no change. I have also checked the coils per FSM and checked for 12v at the coil, and the 5v reference voltage at the boost sensor. I have checked every ground and tried 3 different ecu's (n370 and 2 n374).

The vehical has several odd quirks too, for instance if you move the shifter...... the power antenna goes up and down. I noticed several dosconnected sensors under the vehical, and on the tranny. What is there has been wired using a household extension cords 14guage stranded wire. (What was left was still in the rear.... lol).



The ground wire (black with yellow stripe) is connected, to the body at the strut tower, but I had to run my own 8guage wire to the ground point on the strut tower back up to the batter. The main ground wire for the block was not there, and a 4guage wire ran from the alternator bracket had taken its place. I have moved this to one of the block bolts on the AC bracket (I dont have any longer wire). The car cranks fine and has 115-115 compression per rotor per face.





Any input welcome, thanks guys, its becoming a headache.

 

Completly tore the harness off the car and removed every inch of electrical tape/wrapping. Inspected the whole harness and continuity tested the CAS wiring to the ecu from the connector. 12v current has NO issues passing through. I replaced the CAS plug due to cracked and damaged wiring using just 4 spade connectors. After doing this I can spin the CAS by hand and get fuel and spark. After installing it into its correct location and cranking the vehical, I only get fuel, no spark. I replaced the cas with a tested, known working unit from my own car. NOTHING.



The ONLY think that changes between spinning it freely and where its installed in the front cover is its location. What is with this?

 

It has to be a ground issue. If I can hold it in my hand sperated from the block with nothing but the sheilded wires running to it, it has to be a ground. The only thing I could see causing this is the damn extra ground at the ECU the last mech that worked on it added. He split into the sheilded wirefor the cas and several other sensors, grounded it to a eye hook at the ecu mounting.



The engine ground goes like this:



Black 4guage and 8guage wires.

4guauge goes to AC bracket.

8guauge goes to strut tower

Black with yellow stripe stock ground (whats left of it) runs from rear iron starter bolt like it should, to the same location as the 8guage.



I will move the 4 guage and re run the 8 guage to better spots and remove the extra ecu grounds and see what happens.

 

Sounds like a ground issue of some sorts. Get spark, then worry about the tach. There's a small wire on the drivers side near the firewall that needs to be grounded to get the tach working, if you're having a grounding issue that would prolly explain it not working.

 

Grounds are all sorted out correctly now and should not present any issue.



But.....



Well I decided I better re do the connections at the CAS, I did not trust the crimp ones I used anyways. So I soldered on a extra 4 pin connector to both sides, worked great, got spark every time I would spin it.



Soooo I put it back into its location and cranked it. No spark. I took it out, held it on the UIM and spun it, got spark. So I *ring*ed out the wires to the ecu and as soon as I touched the wiring harness nothing. I tried 2 other ecu's and nothing. Theres still a short somewhere I just cant find it. I have gone through nearly the entire harness. Theres no splits/craked casings even.



I noticed that if the cas is outside the stock location and that after inserting it and it wont spark, it will not spark until I disconnect and reconnect the battery.

 

how's the plug? maybe a loose connection or one of the pins is jacked?

 

On the ECU side?

Or cas? The cas plug is perfect.



The ecu has a bit of abuse, someone hacked in a SAFC, but everything has been removed, soldered, and heatshrunk.



I am going to remove the harness for the 5th time..... and go through it. Lotsa work.

 

Hey man this may sound funny but check your mass air sensor. My computer and my ecu blew in my 86 GXL. It would turn over but had not spark. Recently my car started doing the same thing. I have yet to work on it but for a while it would run and then die. Now it does nothing but turn over. I have an aftermarket ecu but I need more parts to install it. I am bidding for a new ecu on ebay. It may sound weird buy it had me stumped, a few of my friends stumped, a guy at the import shop stumped, and a guy at the mazda dealership stumped.



I don't know if this will help. I hope it does. It was doing the same thing that you have described.

 

theres a 6 pin ground under thet dash, it does very wierd things when its not right. car ran ok though