I recently rebuilt my 1983 L28E NA with stock EFI and have just broken it in. At idle, it's fine. At WOT, also fine. But, at low to mid throttle, I'm finding intermittent hesitation between 2000 rpm and 4000 rpm. The hesitation is accompanied by spikes on my AFR gage, apparently going full lean for some reason?
I did an rpm sweep in the garage to track the behavior. Please check out this video:
https://photos.google.com/share/AF1QipPxmRYeqaIboI-dYGBOa_D8to9BfRFtVQkn6gCEApu5WDoBG8ypbBQ42FPvRJFIXw/photo/AF1QipPUD1Bv65KMuSeHtmpc05PfFT3VL3YosIyob2O-?key=bXhJYlhOUE5ldGE0QzlKN0t2MlQtcWVDV3RvU1B3
At 2000 rpm, it starts acting like there is a rev limiter, but there isn't one. The power seems to be cut in short pulses, which are repeated very consistently, leading me to beleive the ECU is doing this intentionally. The AFR gage shows spikes going full lean, as though the fuel is being cut momentarily and then restored.
Does anyone recognize this?
I'm going to start checking out the TPS, AFM, ECU, O2, and all the associated wiring, but I was hoping maybe someone had seen this before, or had any clues for me?
Thanks,
Nate