I have been having trouble with my EST for a while now. It started as a code 42 error, I replaced the EST module and the code 42 went away but I still have trouble starting my Camaro and she runs like I have a major miss. My question is whether or not the refpulseOK@6.25ms in the Craig Moates datalogger is supposed to be "1" when the engine is running faster than 1500 RPM? Here is some data that I recorded today, showing my refpulseOK@6.25 randomly between 1 and 0... is this normal? refpulseOK@6.25ms I appreciate any help or suggestions here, feels like I'm running the worlds first 4 cylinder smallblock Thanks, -pbIROCZ

At 1500 RPM there will not be a reference pulse every 6.25 msec. Take the RPM and divide by 60 for revs-per-second. Then multipy by 4 as in each revolution 4 cylinders will fire. The inverse of that ( 1 / nnn) will give the time between reference pulses:

(1500 / 60) * 4 = 100, 1 / 100 = .01 sec or 10 msec. between each distributor reference pulse (DRP).

Even at 2,000 RPM there won't be a reference pulse per 6.25 msec:

(2000 / 60) * 4 = 133.33, 1 / 133.33 = .0075 or a DRP every 7.5 msec.

Finding the DRP per 6.25 msec. cutover point is left as an exercise for the reader. . .

RBob.