In a previous post I had problems with my 1993 Lumina 3.1 stalling. Car finally started but would not idle down. It's at my local shop(used them with success in the past) where they found water in the ECM. They initially could not get any feedback from the ECM so they got another one. Once they put the second one in, the car would race and would not idle down. Readings from the ECM did not match with what they were able to read using other sensors: vacuum, temperature, etc. They were able to find another ECM and will install on Monday. Is there anything else I should be having them check? Also had new plugs and wires installed while it was there.

When installing the replacement ECM, was the original programming from your vehicle used, or whatever program was loaded to the replacement ECM?

There are two possible ECMs used for the '93 W-Body 191 V-6s - The 1227127, which was also used in prior years, or the 16149396, which was a '93 version. The latter is basically the same as the '727 but with additional SRAM burned with vehicle-specific information. In either case, the entire MEMCAL (PROM and backup resistor chips) from the original ECM should be used, or at least a MEMCAL with the same broadcast code. In the case of the 16149396, the MEMCAL needs to be exactly the same as well as the NVRAM programming, which may mean relafshing the SRAM (used primarily to control the electronically-shifted transmission).

PCMs/ECMs are not always "plug-and-play" devices.

I'm starting to think that they installed the ECM without any programming. How is the ECM flashed with the original info from the bad ECM?

The basic vehicle program parameters are on a PROM in the MEMCAL. The MEMCAL can be removed from the old ECM and installed in the replacement ECM. The components on the MEMCAL are inherently impervious to water, so unless the contacts on the MEMCAL are corroded from moisture, it should be acceptable for use in the replacement ECM. New MEMCALs are also available through GM Service Parts (they call them "calibrators").

If the ECM is the 16149396, there is probably additional programming to be done. Any place which has the capability to flash program should also have access to the binary files for numerous vehicles (files are available through GM SI, AllData, and several other services). They'll load of a file and burn it to the RAM of the ECM/PCM. There is always the chance that the failed ECM can still communicate, even if the I/O or other functions have failed, and memory can be dumped from it. If not, those files are always out there.

Still don't have my car back. Shop now tells me they are replacing the prom in the ECM. If it wasn't for the fact I've used this shop for years and been very satisfied with their work, I'd have the car towed to another shop.

The obd 1 computers do not need to be programed,the prom needs to be switched to the new one.

Shop had to drain the oil today after finding gas in the oil presumably from idle running so high it was burning through 2 or 3 gallons of gas in 15 minutes. Pulled the new plugs and cleaned also. They finally went to a chevy dealer and got another ECM and installed it with the new prom. Car started right up with what seemed to be a normal idle. It was late so they will check it in the morning to make sure this ECM solved my problems.

What is an ECM?
What does an ECM cost?

ECM=engine control module. The last one I got was $220 with a $90 core return.