I had to change the ECM on my 1996 502 mpi due to some water issues. It got flooded last year but ran okay after that. Over the course of the winter some corrosion set in. Apparently some water made it in the ECM and I had a crank but no start senario after that.

Okay now to the current issue. I bought an ECM from ASM for the stock 502 that is in the boat and it fired right up. That fixed the no start. Now I have an idle issue. It is holding 1300 to 1500 RPMs out of gear but sometimes surges when warm. I cleaned the idle air control with no change so I then put a new one in, still no change. Along with this the temp is holding around 180 with a new 160 thermostat in it. Nothing has changed but the ECM.

We hooked the scan tool up to it and the IAC was at 87 pts. the TPS was at 20 something pts. we were told to adjust the primary throttle blade that has the TPS attached to it until we got a value of zero. Then to adjust the secondary blade to get an IAC value around 20 pts. we could never get the TPS value to drop below 12 or so before the set screw was maxed out. Tomorrow we are pulling the ECM out and I am sending it back to ASM to be double checked for any issues. I dont know what else to do but that. I would greatly appreciate any ideas if you have one. I am out of them.

thanks

Justin