problem with afc shutting off

[dewdew]

sometimes when i am driving my s-afc will shut off for a second, meaning my car will die, then flicker back on, It is usually just for a second, but today it stayed off for a couple minutes. I have already tried rewiring the afc but it is still giving me problems

 

[Omega]

Is it losing power or just plain turning off.

Send it in for repair or buy another one if the later.

 

[turbolarry]

Since all the connections at the harness are good, it might be at the unit.
"This will pull the harness out of it's internal socket. To check it or fix it, carefully unscrew the back cover with the proper small size Phillips screwdriver. Make sure the little connectors are plugged in all the way. "
http://www.roadraceengineering.com/newafcsetting.htm

 

[Staytuned]

Thats exactly what happened to mine last summer. I took it apart and surely enough the inside harness was unhooked form the circuit board.

 

[dewdew]

I checked all the internal connections and they look fine. It is just turning off, usually just for a second. I had a similar experience when my alternator went bad, but when that happened everything else went out first, dim lights, radio turned off, then afc. If my ECU was bad could this be causing the problem? Will the AFC lose power if the ECU loses power. I just had the ECU rebuilt like 6 months ago though.

 

[steve]

Will the AFC lose power if the ECU loses power. I just had the ECU rebuilt like 6 months ago though.

Since the AFC usually gets it's power from the same place that the ECU does, namely the MPI relay, anything that causes the MPI relay to cut out will kill both. Since the ECU controls the MPI relay, teh ECU crashing/resetting from bad caps can cause this.

Steve

 

[dewdew]

well, i had the ecu rebuilt and it is still doing the same thing. I tried unplugging the AFC somewhat. I just unplugged the airflow sensor wires so the afc wasn't changing anything. left all other wires the same and it did the same thing. The ecu and afc are losing power somehow, is there a fuse or relay that i can check. It seems to be getting worse. Instead of flickering on and off, it will stay off for a few minutes.

 

[steve]

Battery terninals, MPI fuse off positive terminal, MPI relay and ECU. That's all there is besides wire. Time to get out the multimeter and start check to see where the fault is.

Where did you send your ECU for repair?

Steve

 

[dewdew]

i sent it to Foreign Auto Computer in FL. It was actually a warranty rebuild. They said it tested fine, but they sent me a new one any way. I just check the fuses on the positive terminal and they seem to be ok. I tried searching more and found a couple things to look at. ISC, Fuel pump relay, and CAS, but if these were bad would this cause my ECU to shut off? I would think not. There must be a short somewhere causing my ecu to lose power right?

 

[steve]

The fuel pump relay is part of th MPI relay on 1G's.
A bad ISC could burn the ECU up but you should have smelled that.
A bad CAS would make the can not run.
Usually none of these would make the power turn off. That happens is the ECU reboots or if the power to the MPI relay drops out.

Steve

 

[dewdew]

Do you think replacing the mpi relay is my next step? Is there any way to test it first?