help car won't start!!
 

My car just died on me on my way home from work the other day... It is a 96 M6 with a few bolt ons, a cam, and forged internals... will not start for nothing... had car towed home and both my dad(mechanic in the 60's-70's before computers), and my friends g/f's dad(head diesel mechanic for aggreko) looked the car over and could not find the reason it wouldn't turn over... i have spark(at the plugs), fuel(at 45 psi), and compression... so it should work... i even scanned the car and the scanner returned no codes... which is odd because i have a lt4 hotcam an the ses light has been on since the cam went in and before the scanner returned the code for the cam sensor... so i am thinking that maybe my pcm up and died... anyone with experiance or advice would be greatly appreciated
thanks,

John
96 Z28
LT1/LT4
M6

my buddy had this same problem it was his opti...he was still getting spark but not enough to make a difference...

I know you said it had fuel pressure but are the plugs wet?

the opti is new(well only two months old)... as far as the plugs being wet my g/f's dad suggested that and we already checked and they seem to be fine...

what brand opti did you use??? was it a gm or was it a part store opti????

GMPP Opti

is it pluged in all the way???? could be a bad module....they go bad time to time

the module for the opti? the plug is in yeah. the thing that gets me is that the pcm returned no codes even though before it returned the code for the cam sensor which would lead me to believe it to be the pcm, i ordered a new one with custom tuning for the cam and everything so hopefully it was that, i will know as soon as it arrives, as far as the rest everything seems like its fine. if you think of anything else it could be please let me know and i'll post what happens after the pcm is here...
thanks,
john

no a bad ignition module....

well even with the pcm in still wont start, its right on the edge like it wants too any more suggestions?
thanks,
john

oh and there is an intake backfire(?) any ideas?

my bet is with timing. either spark or valve.

isn't that computer contolled? any ideas on how i would be able to check?
thanks,
John

Mine has the same problem, and I've already replaced the opti and ignition module. No codes. I'm begining to wonder if the timing chain slipped . . . my car is a '93 with 160,000 miles.

can start
 

just out of curiousity, when you installed the lt4 hot cam in your car what else did you do to it. you know you just cant stick that cam in there and use the lt1 parts on it right? you have to make changes to your timing gears and other stuff well so you can further research it tbyrne has the parts for you to correctly stick the lt4 cam in a car in case you havent put that stuff in yet. peace out "there is no hunting like the hunting of man" E.H. :engarde:

Definately sound like your timing is way off. If the opti is installed correctly, and the plugs have the right wires on them...could be fuel? Have you tried switching wires/injector harnesses?Definately not the right way to go about it, but might give you an idea which direction to go in.

The cam went in a year ago when the motor was rebuilt, and all the components needed lt4 springs ect were installed, and the car has ran fine with the cam since, as far as the opti it also has been fine unless it took a dumb in which case i think i'll get a dynaspark opti replacement... its getting fuel so its not that...
still lost...
john

Sounds like timing. Maybe your chain broke/slipped.

I was wondering if that's what happened to mine, so I picked up a new chain and gears at the dealer. Ever seen a LT1 chain? Those things are massive! It's about 3 times bigger than an LS1 chain. I'll be very surprised if that is the problem.

It's alive!!!! the two tiny ass screws that hold the rotor in the opti backed out, added locktight reassembled and it fired right up... thanks for all your help guys,
John