I'm having a problem with my 96 Z28. Here's the short & sweet version... ANY help you can give is greatly appreciated.

Driving home from work car dies 2X (engine at running temp). Engine cranks normally but no start, after severall attempts, car starts and gets me home (30 miles). Now cranks but no start.
Fuel pressure at regulator is good, 48 psi. No injector pluse and no spark. Engine light is on, code is 420. It's been showing this code for a few months now, I'm waiting to change all 4 O2's because of their location.

Next I replace Opti, and external ignition module. Now car attempts to start but only if my foot is 1/2 way down on the gas pedal. The engine cranks then spits and sputters only while holding gas pedal, release pedal and engine dies. Engine coughing and sputtering so poorly, rpm is not over 300.

No other engine codes besides 420. Scan tool shows no issues.

 

What does the spark look like at the plugs? Nice and blue?

 

Are you sure you indexed the Opti correctly to the cam dowel pin?

 

@bigjoebowski22... I checked spark with a spark plug checker tool not the plug itself. Is it worth checking with the plug?

@Injuneer... The opti has 3 slots on the back as I'm sure you know. 2 slots are "barrel" shaped and 1 is not. That is the slot I used, which was the same as the old Opti used.

 

I'm familiar with what the back of the vented Opti looks like. Unfortunately, many people make a mistake and manage to put the dowel in the wrong slot. It was just a question that I thought would be helpful.

 

That's what I meant, check it with a tester from the plug wires. Check the intake ducting between the MAF and the TB, if it's cracked, it will cause issues. If that checks out ok, unplug the vacuum line to the fuel pressure regulator and see if it's wet with fuel. If all that checks OK, get back with us.

 

Ok, thanks for the help guys. I'll check it and let you know.

 

NO cracks in the ducting between MAF and TB. Even tried a new MAF just to make sure that wasn't my problem. Also NO fuel present in vacuum line to the fuel pressure regulator.

My brother has a GM Tech2 scan tool hooked up to it and dosen't see anything wrong.
UGH!!!!

 

Ok, here was the problem... Seems that the brand new opti that I installed was NO GOOD. We suspected the opti again when the timing on the car didn't retard when cranking. It just stayed at 12 degrees.
Another brand new opti installed and the engine fired right up!