An update on my 97 Z28. I tracked down the fuel issue I had in the below thread to being a kinked fuel line in the fuel tank. Fixed that issue & I know have adequate fuel pressure at the rail.

https://www.camaroz28.com/forums/sho...d.php?t=663150

The car is a 1997 Z28 M6. LE2 H/C, rebuilt 355 shortblock, pacesetter LTs, Moroso CAI, new EWP, Comp Cam Pro Mag 1.6 rockers, ported LE intake, new Taylor OTVC plug wires, new GM LT4 Timing chain, new Delphi 37 lb/hr injectors, new NGK TR55 plugs, new Spec 3 clutch, new LT4 Starter, new Auto Zone Opti, new coil, new ignition module, new Racetronix Fuel pump & wiring harness, PCM for less mail order tune, new fuel filter, new knock sensor. I think that is everything.

Now on to the problem. The car will start after turning the motor over several times & pressing the accelerator to the floor. Once the car starts, it will only run if you modulate the accelerator. When I try to rev the engine it revs slowly & will back fire if reved to about 3K. The car will not run if you take your foot off the accelerator. Car immediately dies. Once you let the car die, it has a hard time starting up again. It tries but only spits & sputters. Coming back after an hour or so the car will crank again with the same problems as before.

Could this be related to the IAC motor? The TPS sensor? Could it be the ignition?

 

It sounds like it might be a timing issue. Timing chain gears misaligned, bad or not installed correctly opti, bad tune?

 

I am comfortable with the tune being good. Brian usually does a good job. Maybe the Opti is on wrong, but I thought I made sure it was in the proper position when I put it on.

 

I had the same issue with my car when I first got it together years ago and the fuel line was leaking inside the tank. I was getting about 10-15psi at the rail and the car would do the same thing. Did you verify you are getting 40+ psi at the rail?

Also, turn the key foward but do not touch the gas pedal. Try to start it...see if that helps at all. Could also be too cold of a spark plug.

 

The tune probably is good. But, after my last camshaft change I started with a fresh PCM file and was getting the same problems you are encountering. I just knew the timing gears and opti were right. But still couldn't fiqure out the problem. Pulled the opti and timing cover, they were both installed correctly. I had a friend send me a fresh stock tune to start the car, which I thought was right. I ended up putting my previous tune back in and the car started perfectly. For some unknown reason the tune my friend and a top tuner sent me was corrupt.


Just a thought.
-Mike

 

Make damn sure the plug wires are going to the right cylinders. I mixed up 3 & 7 not too long ago and it threw me for loops. Ran like total crap similar to the way you describe.

 

I checked that but I will double check to make sure. Oh and FWIW, the odometer is not working.

 

x2 did same thing, ran just as your describing...

 

x3. Did the same thing after my first cam swap. Found out I had switched two and ran identical to what you're describing.

 

Checked the fuel pressure. 40 psi at the rail after priming.

I will recheck this. Driver's side I am pretty sure is right.

 

If the plug wires are correct then try new spark plugs. Some could be cracked and/or arcing or they could be fouled.

 

Arcing may be a possibility. I am running those infamous Taylor plug wires. Problem is I can't check for arcing by myself.

 

Is the coolant temp sensor connected and working correctly? Sounds like its loading up with fuel. Putting the accel pedal on the floor puts it in "clear flood" mode, and cuts the amount of fuel its injecting on cold start. If the coolant temp sensor is indicating too low a temp, its going to start and run like that.

Has it started well and run correctly at all since you rebuilt it?

 

This is the first time it has run since the finishing the build. The coolant temperature sensor is brand new. Is there a method to test it?

 

Shoebox has a writeup on testing temp sensors:

http://shbox.com/1/4th_gen_tech2.html#ect

But the best thing to do is put a scanner on the PCM and look at the reading the PCM is seeing from the sensor. Have you scanned it for codes? Is the SES light on?