jim88-Z52

I had a new engine (mild 383) put in at the end of last year, and it hasn't run right since. It idled high (goes to 2k on start up then settles around 1200). I went to put my Actron scan tool on it but it wouldn't communicate with the ECM. Thinking the ECM might be bad i checked all fuses then put another ECM in(with a custom PROM from Scott Hansen), same thing. I then tried using a very simple code reader i had. The SE light flash 12 repeatedly and only 12. Then i got the laptop out and hooked it up for Datamaster, at first connected up fine and recognized the ECM. When i started to record it would record for a couple seconds then say it lost communication for 4-5 seconds then connect again and record for a couple seconds. It did this consistently for 2-3 minutes till i stopped recording. Trying to sort out this ECM comm problem so i can get some data and find out what the issue(s) are. Car is a 1990 M6, datamaster file attached. Thanks in advance for any input.

FrankieD

Total length of the datalog is about 6 mins. Engine temp reached 143.6 F and Fueling was in Open loop throughout the log. The only time I noticed the RPM's go to about 1800rpm I noticed the TPS % reading went to 9% which indicates a throttle blade opened. Can you verify that you physically tapped the gas pedal during this log? Everything else seems normal. Air Fuel ratio did not go leaner than 15.10 which is great. The "O2 Rdy" was never active during the log. Not sure if the O2 should have been warmed up by then and active.

Cliff Harris

I read somewhere that you need to disable communication with the CCM because it interferes with the data stream output. Does that apply in your case?