HAZ-Matt

iTrader: (8)

I have had a problem this week that has happened three times, only while driving the highway. The first time, on Tuesday, it felt like the motor misfired a couple times and the tachometer went to 0 rpm but the motor was still running fine. After about 30 seconds it went back to where it should have been. Wednesday I had no problems with it and I didn't drive it on Thursday. Today it did something similar twice while driving down the highway. There are no SES lights. The motor mounts were recently replaced, which is the only thing that was new. I think the crank position sensor is near the starter, does this sound like an issue that could be caused with a problem with that, or is there some other thing that would cause this?

Thanks

edit: Car is a 2001 Formula with LS6 parts off a Z06, 85mm MAF, Dynatech LTs.

Formula413

iTrader: (1)

Last year the tach in my daily driver dropped to zero out of nowhere (engine still running). Alternator was toast.

HAZ-Matt

iTrader: (8)

I suspected maybe to see something wrong with the wires to the CPS, but as far as I cold tell they were ok. The one thing I did find when I took a look under the car was that the driver O2 extension had come loose and was resting on the header, and the plug on the extension was partially melted. Is it possible that could have caused the symptoms?

1FST-Z

iTrader: (6)

I experienced the exact same problem after installing poly motor mounts. Turns out we had incorrectly re-routed the CPS wires up and around the starter, which caused the CPS to be partially connected at times. Re-routed the CPS wires so that they were no longer pulled tightly, problem solved!

HAZ-Matt

iTrader: (8)

How are the wires supposed to be routed?

HAZ-Matt

iTrader: (8)

On second inspection perhaps the positive wire going to the starter was pushing on the CPS wires a little bit. I took it off the starter and routed it over the engine mount and then connected it so it doesn't interfere with the CPS wires at all. It seemed like the correct way for that wire to go considering it had heat wrap on part of it and seems like it should be closer to the manifolds than the other wires bc of that. I guess I will need to take it for a spin and see if I made any progress.

HAZ-Matt

iTrader: (8)

I took it for a short test drive that day and had no problems. Today I drove it about 80 miles and haven't had the problem. Maybe one of the things I did fixed it :shrug:

1FST-Z

iTrader: (6)

Yep sounds like it was the CPS wire. As long as it's routed to where there isn't any tension on that wire, all should be well.