My bud's 94 GT, AODE to 5speed conversion, when he datalogs the RPM is not consistent. Even to the point that on a full throttle acceleration run the rpms will go 4100 4120 4150 4100 4200 etc... all over the place...
i'll look at mine, but that is probably sorta normal. i know that at idle, mine can be anywhere +/- 100 of what the gauge shows. there is some hysteresis built into the gauge
When I had my TwEECer R/T, it was the same kind of crap. I ended up making a cheapo inductive pickup and wrapping it around the +1 plugwire insulation and it worked great. (Until I sold that POS to save myself the aggrevation. lol)
I don't buy that it is normal... we did some back to back datalogs in the driveway the other day. Used a mechanical stop to open the throttle... at a stady throttle m car sould vary by +/- 30 RPM, his +/- 100 RPM. By 2k rpm my was VERY consistent and his was even more wacky...
I suspect the PCM takes a signal from the PIP (pin 56) for rpm values. When I installed the Zeitronix WB controller tapping into pin 56 was the only way to achieve a steady rpm signal to the controller.
At the computer. It was easier as I had to cut the NB O2 wires (pins 43 & 42) and tap into 43 for the WB. Additionally, I ran a dedicated ground from the battery to the ECU chassis ground for the WB as well. Just made sense to do everything in one location.