Matt Burns

Car is an 89 Caprice with a 6.0, 799 heads, Torquer V2 cam, Vic Jr. intake, brand new Street Brawler carb, and 6014 box. Box is on a relay fed voltage from the back of the alternator stud, relay is only powering MSD and Carter 4600HP fuel pump, and they are on separately fused circuits. This motor came out of a truck and ran great on injection with no issues. Since the start, the engine will start and idle fine for about 2 minutes, then all of a sudden the idle will kick up to about 1100 and smooth out significantly, run for about 5-10 seconds, then the engine will shut down completely. If you try to restart it immediately it will typically backfire through the carb like the firing order is wrong. If you wait 5 minutes or so it will start up fine and repeat the process all over again. I've swapped cam and crank sensors with known good sensors with no change. I've tried a known good 6014 box from my race car and it does the same thing. The box and the coils are grounded to a single bolt on the valley plate. I have connected to the box while this is happening, and I don't see commanded timing jumping, voltage dropping, or RPM readings looking abnormal. The only fault code is for the coolant sensor which is not connected, and the coolant tables are zeroed out so it should not affect this. My next step is going to be redoing the grounds but I would have thought I would have seen that as a voltage dip while watching the data from the box. If the grounds don't correct the issue I can swap the harness from my race car, but that is going to be a pain in the *** and I am trying to avoid that. Have any of you guys seen this issue before and if so what did it turn out to be? This is a friends car and I don't have as much time to dedicate to troubleshooting it right now as I would like, so I thought I would reach out here and see if anybody has dealt with this. Thanks in advance guys.

Doug G

Have you tried to connect the MSD straight to the battery ? + and -

Matt Burns

So tonight I rewired the MSD, ran each coil ground to the respective head, ran the ground to the box back to the battery as MSD suggested. I also relocated the power feed to the starter from the alternator as MSD suggested since they thought the signal off of the alternator lug might be noisy. Still had the same issue. Wired the power and ground directly to a battery and still had the same issue. I had an MSD 6010 sitting in a box so I quickly rigged that up and the car runs great. My next step will be to pull the 6014 harness out and go over it. I suspect the owner may have pinched the harness under the intake and there may be a wire damaged in the harness. At this point I am very confident it is in the harness somewhere, and likely not the cam and crank sub harness as RPM is always reading even when the car dies and will not restart.

Pop N Wood

iTrader: (1)

Make sure the idle timing control option is disabled. Since you swapped boxes that probably isn't it but worth a try.