Hi all,

My 1985 Camaro IROC-Z with a 383 stroker has a hesitation when accelerating from a stop or low speed, and I can't find the cause. Whether you try to take off fast or slow, it sounds almost like the engine cuts out for a split second, comes back, cuts out, and then goes. Likewise, if you are going slow - say, around 10 or 15 mph and hit the gas, the same thing happens. However, once you are going faster, if you hit the gas it goes immediately.

If the car is in park and you rev it up, it sounds great. No hesitation or cut out at all. It only happens under load.

This has been an ongoing issue basically since I put the motor in back in 2010 or 2011. Since then, I've only driven the car a total of maybe 3,000 miles (probably less), so while the stuff is old, it doesn't have many miles on it.

The 383 is fed by a Holley Stealth Ram fuel injection setup.

I have a high-flow fuel pump that was installed in 2012.

I recently replaced the plugs, wires, cap and rotor as well as the throttle position sensor (and adjusted it).

I swapped out the original ECM with one out of a 1990 car. I had company supply me a file that I burned to a chip after data logging multiple times. According to the company, they saw nothing in the data logs that looked out of place or that would cause this, and I'm 100% positive it happened while collecting data.

The problem seems - I say seems because I'm not 100% positive - to get better as the car gets hotter, but it never goes away.

 

Is there an electrical connection that is breaking under the torque of the engine? Does fuel pressure maintain under load? Is spark being blown out under compression pressure?

 

I'm leaving this here for any future idiots (like me).

Always start with the basics, right? I haven't checked the timing since I initially set it. It was at 6 degrees, maybe a tick below that. Bumped it to 10. No spark knock, no hesitation when driving.