guys, my friend has a 383 LT1 with AFR LT4 heads, intake, nos profiled cam and so on. the car puts out 420 rwhp n/a and on the nos, the rwhp is about ~640+ (if i remember correctly; almost 800 tq.). The car has been tuned for a 200shot and n/a. The car will drive on either tune.
The other day we put in the n/a tune and since then, no matter which tune, the car is not wanting to start.
My friends and I have been throwing up ideas...leaky injector, ignition...??? Anything at all.
Would anyone on here have any ideas?? I know I have not provided much info but thats the core of it.
thanks

 

to add some more info. They just replaced the opti. On a cold start, the car fights to fire up and stay lit. Once warmed up, all starts are easy after that. The cold start has issues.
hope that helps.

 

To add more info, sorry guys for this late stuff but im trying to provide core info as i think of it: its 94 convertible Z28 with a 6 speed.

 

Eliminate the possibilities of fuel leaking into the intake by monitoring fuel pressure after the pump is shut off. If pressure leaks down quickly, that may be the problem. He may even smell fuel in the oil from an excessive leak. Most Common cause is a leaking injector. A much less common cause is the FPR diaphragm leaking fuel into the vacuum line.

Another possibility is the ignition system has issues that while cold, the fuel is harder to light off since it tends to condense in a cold cylinder. When the cylinders are hot, the fuel coming in stays highly vaporized when it hits the hot cylinder walls thus making it easier to ignite. If it has an aftermarket ignition, try going back to stock.

 

thanks for the tips. I will convey the advice and hopefully it will yield some positive results.

 

Hey guys, same thing, no firing.
Replaced the opti, checked fuel ( as per previous advice) now going to do cylinder compression check.
Any ideas?