Originally Posted by DJ23GSX
The part number on my leaky ecu is MD145903
and the rebuilt one is MD128625. I understand the rebuilt one is a fwd but does that make a difference?
Is there any way i could tell if the shop that rebuilt this ecu used a different year circuit board than the part number states on the case?
MD145903 90 Federal Turbo MT AWD ECU
MD128625 90 Federal Turbo MT FWD ECU
If the ECU actually matched the case the four digit number on the edge connector will match the last 4 digits of the E2T number on the label on the top case.
For example the MD128625 is E2T34474 and the connector should say 4474.
A correctly working ISC will start out at around 120 steps when the ignition is first turned on and than after the engine fires it will drop to 0 steps until the FIAV begins closing. Then depending the the ECT and RPMs the ISC will work it's way up to 13 to 20 steps at idle on a warmed up car and stay pretty stable, not jump around, not max out in either direction.
The quality of final testing, including the ISC operation, ranges all over the map on rebuilds. One test is to check how the car idles up when you turn on the AC and idles down when you turn it off after a ECU reset.