Quote from
65sohc on May 24, 2020, 11:56 am
65 GTO with 406 sbc, 10-11 inches vacuum at idle,5 speed stick, early style fuel commander with return line, fuel pressure within spec.
On light acceleration from a stop the engine flattens out and AFR goes to 15.5-16 in the range between 1800 and 2500. The more lightly I feather the throttle the worse it is so it doesn't seem like the typical hesitation associated with an accel pump issue. It also does not seem to initally go rich and then lean out. Nevertheless I tried increasing and decreasing the accel setting. I also disabled closed loop below 3000 rpm and it didn't change. I checked for vacuum and exhaust leaks and found none. It does seem to be associated with higher manifold vacuum. Also it only occurs when the engine is at normal operating temp which is 195-205.
I filled out the tech form on the FiTech site, hit submit, and then it said processing for the next hour and never went through.
65 GTO with 406 sbc, 10-11 inches vacuum at idle,5 speed stick, early style fuel commander with return line, fuel pressure within spec.
On light acceleration from a stop the engine flattens out and AFR goes to 15.5-16 in the range between 1800 and 2500. The more lightly I feather the throttle the worse it is so it doesn't seem like the typical hesitation associated with an accel pump issue. It also does not seem to initally go rich and then lean out. Nevertheless I tried increasing and decreasing the accel setting. I also disabled closed loop below 3000 rpm and it didn't change. I checked for vacuum and exhaust leaks and found none. It does seem to be associated with higher manifold vacuum. Also it only occurs when the engine is at normal operating temp which is 195-205.
I filled out the tech form on the FiTech site, hit submit, and then it said processing for the next hour and never went through.
65 GTO with built 406 Chevy smallblock, Fitech
