circuswings

Last Saturday my z06 shut down on me at an autocross event. Sounded like a belt went as I came into the finish line. It was idling after the line and then just shut down on me. When I went to try to restart, it was abnormally slow to turn over (almost like a bad starter or low battery) and would not start. Ended up getting a cam position sensor error code.

Took the car back to speedinc - they checked it out and replaced the cam position sensor and said it ran fine for them. I picked the car up this morning, and on the drive home I was doing about 40mph and the car shut down on me when I put the clutch in. Again, when I went to fire it back up it sounded like a bad starter or low battery.

I did some searching all weekend about the issue I had, but I wasn't able to dig up anything that seemed like a similar problem. Essentially the same thing happened to me this morning as I experienced last Saturday. Has anyone experienced something like this, or does anyone have ideas as to what it might be?

Mods are: k&n intake, nick williams 102mm throttle body, fast lsxr 102 intake manifold, ported ls7 heads with ss exh valves, widow-r cam, kooks LTs w/ xpipe, mcleod rxt clutch and mcleod lightweight flywheel. Most of that was installed in mid March, and the car has run flawless until now. Has a little over 35k on the odo, maybe 3k since the work in March.

Werks

I ran into the same thing a week ago at the track. The air conditioning belt came off and hit the cam position sensor damaging one of the wires. Had the dealer replace it and everything was fine. If you are still getting error messages I'd just check to make sure that the plugs are fully seated. If you can get under the car you should be able to access the plug. The positioning sensor it's self is on the front of the block on the drivers side slightly to the side and above your damper. You will see a wire that comes off of it that wraps around the side of the block and plugs into a harness there (which is just below the front of your headers). I'd just double check that the plug in the harness is fully seated.

circuswings

Thanks! I'll look for this today. AC hasn't been working lately either but I assumed that was just due to me beating on it at autocross.

circuswings

So I picked the car up today. The GM service center said that the battery, alternator, and starter all checked out ok. They replaced the crank position sensor. They stated that they test drove the car and it started up fine even after being warmed up.

The car fired right up for me and then shut down after idling for about 5 seconds. That has never happened to me. I fired it back up, it idled alright, so I went for a drive around the block. Immediately after leaving the dealer, it shut down on me while braking with the clutch in. When I hit the start button, same symptoms as earlier where the starter did not want to turn the engine over fast enough. I let the clutch out and it fired right up. As I was entering the dealer lot, the same thing happened and I again had to let the clutch out to get the car to fire up.

Bad starter solenoid?

glenB

Battery cable connection at the solenoid, but if it is loose it's probably burnt the connection as well

circuswings

For what it's worth, they would have had to remove the starter to get to the crank position sensor. Wouldn't they have caught that while checking the starter to see if it was ok?

glenB

These are the same people that said everything is OK and installed a Crank Sensor only to have the problem come right back and you question me?

You suggested the solenoid, wouldn't they have determined that by testing the starter?

Did anybody read the freeze frame data ? Was it a 340 or 341 code?

Maybe you can get the tech to ride along and record the events when the car stalls to give you an idea of what you are losing.

circuswings

What I meant was to ask whether or not that was something that they should have detected when taking the starter off and doing whatever testing they said they claimed to have done.

The first time the car shut down it threw a 340 code. The next time, I didn't see the scan myself. However, I did try to start the car unsuccessfully multiple times - the unsuccessful starts may have caused the crank position sensor error.

Having the tech ride along and data log sounds like a great idea. I'll try to do that on Monday.

Gary '09 C6

sounds like the dealer has no idea what they're doing !

glenB

Cranking by itself won't cause a CKP fault. 9/10 when a CKP fails, they stay dead.

Bad CMP will cause an extended crank, possibly once it starts a slight rough idle and then smooth's out. A bad CMP will allow the vehicle to run in batch mode or bank to bank, I forget, but it will run.

I would drive it until you get another CEL and then review the freeze frame data for possible clues. Then clear the code and have the tech record a drive until it fails.

The bottom line is that the tech needs to see it in a failed state, that's where the freeze frame comes in partially, even if it's for just a few minutes to determine what is lacking.

0Anthony @ LGMotorsports

Something else is going on.....I would look deeper into it.

If the car looses the cam signal it will still start and run and just base everything off of the crank position sensor. It wouldn't shut down. It would take longer to start the car, then set a code for the cam sensor....then run off the crank.

It wouldn't be slow to start, and it wouldn't just die on you.

If the crank signal was lost...it shouldn't even start.

I would look further into it.

palindrome1H

Yeah Anthony is of course right. Something else is going on here for it to die like that. No limp mode eh?

0Anthony @ LGMotorsports

Drain the oil and filter it....check for debris...

Cut the filter apart to.

The only time I have seen something similar to this, the car was low on oil and ended up spinning a rod bearing......

The metal debris went through the engine, stuck to the cam sensor (its' magnetic) and the hard starting and dieing was due to the bearings stacked on the rod.

Now, I'm not saying it is that, but again....I would look further into it.

circuswings

Just to clarify - the car doesn't go into limp mode or make any odd noises while running. It's almost like there's a big drain on the electrical system - the tech noted that when he received the car the battery was too low to turn the car over, but switching batteries solved the problem. However, he said that my battery checked out OK on their tester.

z51vett

Just a wild guess if ac not working could compressor be failing and pulling engine down at idle speeds. Oh and I would check oil and filter as advised by Anthony.
z51vett
Doug

0Anthony @ LGMotorsports

Ok, but the car should run on the alternator once it is started with no battery in the car at all.

Dirty Howie

Interested to see how this turns out.


DH

circuswings

So after a lengthy discussion on the phone today, I explained that the issue isn't with the tuning (they were trying to convince me that the timing was causing it to stall) and that I was pretty sure that the starter was shorting the system when hot. About 3 hours later I get a call explaining how they let the car warm up and were shocked to find that, when hot, the starter would begin to draw a high current. Should be picking the car up tomorrow evening with a new starter installed.

wolf8218

What do you think might have caused the short? Defective part or change in operating conditions?

circuswings

Headers were getting pretty toasty after autox runs with less than 5 mins in between runs. Probably progressively cooked the starter throughout the day and on that last run really did it in (started getting a bunch of electrical errors right at the end of the lap).