FAST Expert Needed - Dist Issues

[bigblockcamino]

Tried getting the motor fired up again after 6 long months of taking a break. I bought an XFI kit from Frank @ Prodigy last year and I'm still #*king around with it trying to get it to work. I got fed up after the distributor module blew up and I threw in the towel for a long time.

So far, I have burned up 2 distributor modules trying to get this damn thing to fire/run. I have been chasing down some interference that is causing the RPM's to spike all over the place when I'm trying to start it. I thought it might be ground related, but since then I have switched over to a 1/0 cable to the starter, and the same for the ground to the water pump bolt. Also added another 1/0 ground to the rear bolt on the cylinder head to the chassis and another smaller ground from the block to the frame. I think that should be enough grounds.


At first the modules work fine. I apply 12v, set the 50 ref angle, and lock down distributor. Easy enough, done. Cam/Crank LED's on the XFI/module are lighting up just fine. However, the points light was not lighting up though on the XFI. I went into the Dashboard and made sure all the parameters were correct, saved to the XFI, and tried again. Now the points lights fired when I tried it again. Strange. I figured I was home free at this point.

Cranked over the motor again and still seeing the huge spikes in RPM all over the damn place. Now the LED's on the module are both lit up, and I'm getting nothing on the XFI for Cam/Crank LED's. WTF...You gotta be $hitting me, wasted again.

I really don't know where to go now other than to throw this POS FAST distributor in the ***** can and go back to a reliable HEI.

I did try to isolate a few things in the process, I unplugged the injector harness, disconnected the negative side of the coil, disconnected the coil wire to the cap,Crank trigger is looped. I thought the plug wires might have been causing the RPM spikes, still no luck. The MSD 6Al I'm using tests out ok by grounding the white wire, but it's very old (10+ years)

This is the same damn reason I stopped working on this POS last year. There was another person that had the same exact issue I had(interesting to note he had an MSD 6al as well). He fixed it by wrapping his FAST harness with foil but I never did hear what was causing his issues.

I have been talking with Brian on EFI101(turbonova). Anyone else have some suggestions??

[Fuelie Nova]

I have had great luck with my fast dist. Are you sure there is not a wiring problem?
I would forget about the points input for now, replace the module if it is bad and get it to where it will crank and the cam/crank LED's will light light up correctly. I would do this with the point wire disconnected from the MSD and the fuel injector harness unhooked.

Once you get that, if you can crank with no problems and have the led's maybe the problem is in the points output off the msd.

Have you literally traced the wiring on the harness back to the xfi connector at the ecu and verified everything? Mistakes do happen.

Brian is one of the best.

Tom

[4mul8ion]

The way I’m reading what you described, it sounds as though when you key on the car and provide 12v the distributor sync lights up showing that the system is properly aligned and ready to go. When you crank over the car you’re seeing the spikes in the RPM signal. The car does not start. The module is now cooked.

With that read back, consider this: What’s the condition of your starter? Is the starter slow to turn the motor over? Has the starter been over heated? Really high compression ratio?

Pardon the “Is it plugged in?” type of diagnostic questions, but I’m thinking if the starter is pulling too much current from your system as the starter gear turns the flywheel and then spikes the system as the starter freewheels as it's cycling might explain the spikes in the RPM you’re seeing and the smoking of the distributor module. Is the battery supplying enough power to crank over your engine and still putting out the minimum required power for the XFI system to operate?





Kevin

[bigblockcamino]

The way I’m reading what you described, it sounds as though when you key on the car and provide 12v the distributor sync lights up showing that the system is properly aligned and ready to go. When you crank over the car you’re seeing the spikes in the RPM signal. The car does not start. The module is now cooked.

Not true, I was able to turn over the motor several times. Cam/Crank LED's on the XFI were flashing. The points light was not. The spikes are due to noise from either the MSD or picking up some other interference. I'm going to move the MSD wires off the battery +/- and see if that changes anything. Of course I need to get another module first.

With that read back, consider this: What’s the condition of your starter? Is the starter slow to turn the motor over? Has the starter been over heated? Really high compression ratio?

Starter is brand new/cranks the motor over fine. 10.5:1 compression. Cranked over slow after attempting to start a few times. Charged the battery back to 100%.

Pardon the “Is it plugged in?” type of diagnostic questions, but I’m thinking if the starter is pulling too much current from your system as the starter gear turns the flywheel and then spikes the system as the starter freewheels as it's cycling might explain the spikes in the RPM you’re seeing and the smoking of the distributor module. Is the battery supplying enough power to crank over your engine and still putting out the minimum required power for the XFI system to operate?
Kevin

Here is an example: