87 FC3s, new motor.. High idle, no tach
 

Just did a motor swap on my 87 n/a FC. Other motor had the rear rotor blow out.

Did the swap, everything seemed to work out alright. Then when we tried starting it.. mixed up the neg and pos terminals (yay, yes I know this is an uber fail)

Only burnt out 2 fuses. (battery was dead)

Bottom line, car idles high, no tach and idle adjust screw does nothing.

I had to swap my BAC, TPS and CAS from old motor to new one.

Retimed car correctly (runs excellent). Since my BAC and TPS workd on my other engine then I'm assuming they are okay.

I'm hoping I didn't fry anything else that I don't know about that is making the tach not work and the car idle at what sounds like ~2krpm.

When timing the car and checking it over via the trailing plug wires, timing light did not pick up a signal O.o

Its dark out now and I will put a volt meter to the "bullet y/l" connector for the tach to see if its outputting anything.

Maybe I missed a fusible link? All the main fuses looked okay and since it runs and drives fine other then high idle and no tach I don't know what to look for.

Anyway, thanks for the insight.

Mixing up the battery cables can fry a lot of things before the fuses blow. You may have damaged the ECU, among other things. Also, you can't set timing if the engine is above ~1k RPM. The ECU advances timing above that range, but the light should still flash.

Well I timed it and it seemed to be running alot better then before I timed it :P

Checked tach signal from trailing coil (from the bullet conector) 0V read. Makes sense because when I tried timing the trailing, no signal was picked up from the timing light.

Check the resistance of the coils, each 0.8 ohms. (FSM says anything below 1ohm is okay ? )

Now i'm going to go check the ignitor.

I'm hoping I didn't damage the ECU but I have been driving the car around and it runs as it did with the old motor (more peppy, and high idle ofcourse). I'l also be checking the throttle body to see if something is stuck : /

The 2 prong connector to the coils are both + ~12-13V

When I started testing my coils to see if they where okay and when I put them back in i just plugged in the 4 prong connector (from ecu and tach)

Tach started working. So I was like "great!"
Turned car off, then plugged the 2 prong connector back in and... no tach again..

*sigh*

Any ideas? Need my tach to work to see what my idle is to find my high idle source :P (and to time properly)