dlbchik

I just replaced the engine of my 88 GTU. The car had lost compression and sat for 6 months. I replaced it with a used engine because the seller decided to go with a V8, but swore it ran fine. Anyway, the engine is in, and for some reason I am getting no spark at all. I replaced both coils with my boyfriends 90 GTU, and they didn't work in mine, nor mine worked in his. We realized that the ignitors are not getting power. ??? The car cranks, fuel gets into the engine...but no combustion.
Any ideas on troubleshooting? Bad wiring harness? Or possibly just something simple we are overlooking?
Any input is appreciated!!!
Wishful Thinking in KC

marcus219

i have a similiar problem..but im not getting fuel...at least properly...fuel gets into the engine, but i tested injector (primaries) wires with a connector and bulb, cranked motor, and the buld did not light up. I'm thinking my wiring harness might have a short or something.

HAILERS

Pull the small white plug off the lead coil assy(front assy)Put a digital meter on the black/yellow wire with the key to ON. Should have 12v. No volts. No spark.

Check all the fuses in the engine bay near the left front strut tower.

Check all the fuses in the car. Looking into the box, especially check the third row from the bottom. Then check and made sure all of them are good.

dlbchik

OK...
All my fuses are fine. However, I am not getting any power to the coils...wiring harness, maybe???
Also, when preparing to crank the car, the up-shift light is on, and after 15 seconds or so of the key in the accessories position, the buzzer goes off w/o stopping. I am fairly concerned that a wild goose chase is about to happen...
Any ideas other than the wiring harness and fuses?

Dana

HAILERS

Sure. Go to the ECU, under the rug where the passengers feet sit, and disconnect the smallest plug. looking at the rear of the plug(where the wires insert) see if you have 12v at pins 3C, 3E, 3F and especially 3I and 3J. With the key turned to ON.

Actually, if you don't have voltage at the black/yellow wire at the coil assy, then you might take the plug off the MAIN RELAY and check for voltage at the Black/Green wire and the White/Blue wires and heck, the black/white wire when you go to start. There are two plugs on the Main Relay. The B/W is on the big two prong relay and the B/G and W/L wire is on the four prong connector.

Do the main relay first, then the ECU.

Make sure the little white plug on the cas is connected up.

HAILERS

The main relay looks like this jpg and its located next to the trail coil assy:

HAILERS

The ECU plugs look like this as you look from the wire side:

And just how did you determine that the plugs are not firing??? /And did you use a meter on the black/yellow wire at the Lead coil assy????

hypntyz7

ON a less technical approach than that of hailers, (you know how we do it in TN), I would say to fool with your air flow meter, after having performed his advice. I have done a few such engine swaps before on s4 cars with identical problems, and for some od reason, be it poor wiring, connections, or whatever, sometimes trying another afm will immediately yeild spark. You can check this by simply unplugging your existing one, then re-checking at the plugwires for spark. Give it a try, itll only take 5 minutes, and its happened to me 3 times...

dlbchik

ECU is getting no voltage on smaller plug, nor leading coils. Trailing coils only get 1 volt on L/R wire. Main Relay only gets 12V on W/L wire...others nothing...
This is all over my head.

HAILERS

Not over your head. If you only got 12 on the white/blue(W/L), that gives us a clue.

Its the GREEN/BLACK that should have 12v all the time and it does not accoring to you. That wire gets fed from a 40amp fuse in the engine compartment. Double check that fuse.

By the way, when the key is turned to the ON position, do you hear the MAIN RELAY click????? You want all the plugs on when you do this.

It seems its a bad fuse or somehow that wire is open b/t the relay and the fuse box.

dlbchik

OK...trying to decipher the wiring diagram in a Haynes, I have realized that for some reason, I am not getting any power to the B/Y wires...the W/B and W/L are showing power when "ON". We put the Main Relay on the '90, and it worked. So I wonder how to track down the B/Y. According to the manual, that wire does almost everything.
The Main Relay does seem to click. I also rechecked all fuses...all look fine. Maybe a crack wire?
I am about prepared to put the harness from the '90 on it, just to start it and move it from my boyfriends buddy's house, but I worry the connectors will not all match after pulling both harnesses off.
OK...how should I go about trying to get power to B/Y? The B/Y shows power on the 90. I also assume this is why no power gets to the ECU...

HAILERS

The black/yellow wire at the coil assy , gets its power from the MAIN RELAY. When the MAIN RELAY is pulled in, it makes continuity b/t the black/yellow wire and the BLACK/GREEN wire via the contacts in the relay. So you need to pull the relay plugs, and see if you have 12v on the BLACK/GREEN WIRE. There should be 12v on the Black/green wire 24hrs a day.

If there is no 12v on the black/green wire, then the fuse is shot(40amp in the engine compartment) or the wire has a break in it.

Haynes manual wiring diagrams.....gooooooooood luck!

Damn. If the relay is good in your friends car, then it just has to be no 12v on the black/green wire at the MAIN RELAY.

No voltage at the ECU?????? Starting to sound to me like the MAIN fuse in the engine compartment is shot. Thats the one that does not pull out. You have to unscrew a bolt/screw on the side of the rectangular box to remove it.

I don't have my wiring diagrams with me right nowk but I've seen a similar problem and it came down to a single wire. That wire is located about six inches below the rectangular fuse box. Its a single connector. A black wire. If that wire has seperated or the connector come apart, you get the symptoms you are getting. Can't miss that black wire. Its the only one there. That wire or the 80amp main fuse one.

HAILERS

Tell you what. Go to this thread: https://www.rx7club.com/forum/showth...threadid=73780 look for a reply from HAILERS, and in that reply I had added a jpg. Open the jpg. That is the wiring diagram for your car. See the MAIN RELAY? The black/green wire and how it goes to the fuse box in the engine compartment. It has to be a broken wire, a blown fuse, a blown MAIN 80 amp fuse, or that single black approx 12ga wire about six inches below the fuse box.

You might also read that thread. See how he found that the 7.5 amp fuse was blown in the crew compartment??? Its the one that goes from the 60amp fuse to the 7.5 amp fuse(engine) to pin 3J on the ECU.