Yet another MSD crank trigger wiring question

[Adger Smith]

Do you run an electric water pump?
I had a pump go bad(Leak) at a race. I had a spare in the trailer. No issue because I had time to change between rounds.
Next round I had a hi RPM stutter show up..
Changed the crank trigger pick up. Stutter is still there.
Sat there in the pits and thought the problem through.
Next round I kept the pump on during burn out and turned it off as I staged.
No miss that run.
When I got home I put a seal in the first pump and put it back on the car.
No miss next time I ran the car.
My conclusion is the pump was a radio station that produced RFI that interferes with the MSD. Probably the pickup since my V-6 uses a cam trigger and close to the pump.

[Dirk Olson]

May be out in left field here but sounds like a noise issue? check your grounds.

Dirk

[Joe Schweigert]

Do you have a TPS ? I also had a similar issue with a Holly System Probably not the crank trigger

[Rob Petrie E395]

Originally Posted by Joe Schweigert

Do you have a TPS ? I also had a similar issue with a Holly System Probably not the crank trigger

Yes on TPS. Its a GM TPS sensor. Same one GM used when these cars were built. I'll look at it before I tear the C950 out. And see if its acting unusual. But don't remember seeing anything on data logs in the past.

[Jeff Niceswanger]

If your TB has the long old style ob-longed TPS plug get the Steathram harness which is # 558-101. If it has the small round TPS plug get the 558-104. Both will plug right into your 558-431Cam/Crank (Trigger) harness. The 431 will plug right into your new 118 crank trigger hall effect sensor.Yes, you can just tie off the cam sync plug if you are not using a cam sync. The white wire goes to the points input on your MSD box with both harnesses.Make absolutely sure you take both 12 gauge red and black supply lines directly to the positive and negative post on the battery.. DO NOT put the red wire on the Kill switch. I've seen this many times and it will give you all kinds of stupid random issues.

https://documents.holley.com/techlib...10555rev16.pdf

[Rob Petrie E395]

Well I didn’t know the 558-104 harness existed until I just read this. So I have the 558-101 harness and just bought the correct connector for the Iac valve (I also have the adapter from square to flat connectors). But once I got it. I thought it would look bad so I ordered the right connector from Holley. I have the right connectors for the TPS too. But wish I had known this when I was ordering. Uuugghh. I took the first of the 3 Holley classes a while ago. And they really tried to drive the point home about connecting to the battery. I run a battery with top and side terminals. So it’s easier to charge between rounds. So my plan it to run the car off one set of posts. And the ECM main power harness off the other set by itself. One thing other thing told us. Is if you wire the main power harness to the kill switch or somewhere else. And someone hits the kill switch while the car is running or Key on engine off. It can delete the global file. Can you imagine the pain in the rear that could be?

[Jeff Niceswanger]

I've had a couple lose the tune. A real slow drain on the battery to where it goes completely dead will lose them. Like leaving the water pump on all night or such. Always keep your tune on your laptop or a flash drive. Or both.

[Rob Petrie E395]

Originally Posted by Dirk Olson

May be out in left field here but sounds like a noise issue? check your grounds.

Dirk

I'm thinking that too. I suspect since the MSD box and the FI ECM are both inside the car on the passenger floorboard. Thats got something to do with it. Because the crank trigger is on the left side of the engine. And the coil is on the front of the Left Cyl head. Don't know if the wires are just too long. Or if the long coil wires are causing noise and messing up the crank signal. I can't data log it. Because my data logger is part of my FI. And it does it when it first starts. Any ways I'm making a ton of changes to the engine. So it'll require tuning. Rather than keep fighting the C950. I figured I'd just make the switch now and redo all the wiring. And hope I find the problem.

[Rob Petrie E395]

I think I posted about this problem several years ago. And you had told me about the water pump EMI back then. So I tried that by putting the water pump on its own switch. Didn't help. But it was worth a try. Thank you for the suggestion. I'm leaning towards a EMI problem. Just have not found it. Hoping when I rewire the car this time for the new HP system I find the problem.

Originally Posted by Adger Smith

Do you run an electric water pump?
I had a pump go bad(Leak) at a race. I had a spare in the trailer. No issue because I had time to change between rounds.
Next round I had a hi RPM stutter show up..
Changed the crank trigger pick up. Stutter is still there.
Sat there in the pits and thought the problem through.
Next round I kept the pump on during burn out and turned it off as I staged.
No miss that run.
When I got home I put a seal in the first pump and put it back on the car.
No miss next time I ran the car.
My conclusion is the pump was a radio station that produced RFI that interferes with the MSD. Probably the pickup since my V-6 uses a cam trigger and close to the pump.