Well i thought i had it figured out but... wrong answer. Well here is whats going on, i just swapped out my TPI for a HSR on my 88 iroc with the comp 08-306-8 roller cam 30lbs SVO injectors, Brodix heads, MSD digital 6+ box, MSD coil, factory distributor with a pickup & mod only about 6 mouths old {ran fine with my TPI} Autometer tach and a custom eprom by LSRacing. With the car running at 1000rpm's and a scanner hooked up the computer is saying its running at 2500-2700rpm's, and with my tach at 2000rpm's the computor reads 5850rpm's. I checked the 4 wires running back to the ECM from the 4 pin on the mod and they are all ok and in the right spots, all the programing and sensors are checking good, jamy from LSRacing even got my BLM at 128 with out having the car so i dont see the problem in the new prom. A friend owns a dyno shop and told me to find out what wave length the signal was from the distributor to the ecm, a fellow member on here said it was a 5V square wave. He was wondering if we could take the signal from the tach drive off the MSD and pipe it into the ecm, of course i would have to run a diode inline or something b/c the msd tach drive is a 12V square wave plus which wire is it that carries that signal from the distributor out of the 4 wires to the ecm. I would rather figure out what could cause this problem, any help would be great cuz if i dont figure it out soon i will be converting to carb. I tried a different coil, mod, and running it without the MSD but no change. Thanks Chad