Here it goes

about 3 weeks ago i get the car (corvette) ready for the track. Basically just changed the wheels, uploaded the track tune and took off. The car drove fine to the track with no problems.

I get to the track, and all of the sudden, it is hard to keep the car running. I just figured something with the idle, i can take car of it later. I get to the staging lane, hit the 2 step and take off. The car is good in first, and second, stutters in third and dies at WOT.

Get the car home, and i blew out part of the head and the head gasket. I removed the heads and bought another set of Ported heads, check all the cylinders and pistons. NO PROBLEMS THERE. Leak down test showed great.

I put the motor back together and it won't start!!! It cranks and acts like it is firing on the wrong cylinder, or at the wrong time. As i am cranking it acts like it is compressing and stoping me from turning over after about 3 secs.

If i unplug the coil packs and injectors, it cranks over fine, no mechanical issues.

Thing i have already tried:

1. checked all grounds, and double check. All are good
2 Changed the Crank Sensor and check the wirng to make sure there were no shorts
3. Changed the cam sensor
4. Revmoved 2 step (synergy)
5. Changed the computer to a new one!!!
6. I have not looked at the reluctor wheel, but i can feel it through the hole for the crank sensor, and it seems fine.

Worst of all.....NO PCM CODES

Any ideas

Thanks

 

try adjusting the flux capasitor a little

$5 for trying?

foldedsteel@sbcglobal.net



good luck man..sorry about your problem.

 

Can't adjust it, my mr fussion is broken

thanks for looking anyways

 

Could the timing chain have jumped a tooth or two?

 

I thought of that, but it would be way to hard to skip a tooth and not break. Not to mention, i think it would have to skip a few, then i would have valves hitting pistions. But it is possible, i think i may end up pulling the motor.

 

Are you absolutely sure that the grounds are OK? I thought so when having a similar problem & there was a hairline crack in one of the ground connectors that was causing the problem. Why would the reluctor be an issue if it hasn't been changed & the "new" computer is the same model year? What tune is in the new computer? Hopefully not the same tune that blew the head gasket (& head?). What happened to the head?

This is LS1TECH. The help we've gotten far out weighs the help that we offer. To me, that's payment enough.

 

We had a guy that updated his heads and had to update the coil brackets. He switched around the connectors on a few of the coils.The car sounded just like a gen 1 that was 180 out.very strange for a genIII but it didnt take long to figure out the thing wasnt firing in order. We redid the connectors on the coils and it was fine
FWIW

Good Luck!
Brent

 

I also agree with the coils. If it's not firing right, but turns over fine mechanically, the coils are the best place to check.

 

Thanks again fellas

This is a 99 model vette, i had the computer uploaded using my vin number, so the computer is fine.

It is also the coils that come on the bracket, so you cant get them out of order, they stay hooked up. I also tried another set of coils both sides off of a buddies car, and still nothing

The reluctor wheel is not stock. It is a billet crank from scat. I think i remember the reluctor wheel being welded on, so it shouldn't have moved. I checked all the grounds on the car, and even reground the ones in the nasty ground assembly from the factory.

The catch is, it was fine for a while, then just went bad. What ever this problem is, is the reason the headgasket blew, and took chunks of the head with it.

 

Sounds like the ignition timing is too advanced. Especially if you're seeing the compression fighting back only when the coils are hooked up. May have to doublecheck that reluctor to make _sure_ it's welded...

 

i had a problem just like that but it was with my mustang. it ended up being the IAC (idle air control) had just barely came unpluged. check the plugs around the throttle body. just IMO
thanks
john

 

This is exactly the problem, but how did it happen, and why is it still happening is my problem. I can feel the wheel through the crank sensor hole and it seems ok, i don't think it has moved, and if the crank wasn't reading, it would just turn over, not even try to spark...right??

 

I have checked them, all seems fine.

Thanks

 

Due you have acess to an osciliscope ? if so can you crank the car monotoring the cam and crank patterns and put up the snaps shot. You will need a tiem divison of 50msec per division to catch the entire crank cycle and 1-3 volts AC on the crank and 0-8 volts on the cam.You will need at least a 2channel scope and i would need both patterns to be displyae dsimultaneously. With these i can see if your reluctor wheel has spun or if the cam is broken.

 

No i dont have access to one of those. What i am trying to do is get my hands on a TECH 2 from GM and see how fast the crank is spinning in connection with the cam. See if the sensor is reading wrong, or if the cam has backed out or the timing chain skipped a few teeth

 

Did you get this resolved yet? (just curious what you found out...)

If the wheel rotated just a bit and then stayed there, it would throw everything off a bit, but it would still try to start. (unless the pcm cross checks the crank and cam sensors to each other and gives up if they're too far apart from each other.)