1990 Lumina is the ECM my problem?

[Downtown]

I just purchased a 1990 Lumina 3.1 relatively cheap because the old lady owner did not like the way it ran. I hope its an easy fix. It seems to run rough... almost as if there is a miss in the engine. I am not car savy at all. I contacted a chevy mechanic and he said it is most likely a bad Electronic Control Module. Anyone have this problem or any suggestions? It is a nice car in great shape I just want it to run smooth.

[sysopt]

To hastily blame the ecm isnt very wise. If it idles poorly but runs alright otherwise check for vacuum leaks. Have your mechanic carefully diagnose the ignition system, fuel system, and sensors. If everything tests ok then you can blame the ecm.

[Downtown]

It not only idles rough but it runs rough as well and the last owner said it stalled a time or two... Her mechanic told me today he checked everything but he has no experience with the ECM ...i think he has no idea at all.... I dont wanna pay a crappy mechanic to check and find nothing again how can I check this myself?

[sysopt]

To properly diagnose engine performance problems, youll have to buy some tools for testing, compression gauge (~$30, tests condition of engine), fuel pressure gauge (~$40, make sure it works for your car!), vacuum gauge(~$20), timing light(~$35, only if your car has a distributor), and a multimeter(~$20, for all sorts of electrical stuff).

If you dont understand how to use these tools, I'll refer you to actron's (popular tool company) user manuals web page:

http://actron.com/cgi-bin/web_store....d=6481271_3773

But before you run out and buy anything, pop open the hood and look for anything that does look right: corrosion, loose wires or anything loose for that matter, damaged components, bad grounds, etc. aka preliminary inspection...very important.

OK, now to the actual diagnosing...First thing I like to check is the ignition system; its usually simple and quick, but realize this system is absolutely essential to a well running engine. Get some gloves or an ignition wire puller (yeah I know millions of tools, get used to it) and pull off each wire while the engine is running; do you hear (pop) and see (blue/purple line) the spark arc? If you do, you know everything up to the spark plug is alright. If not you may have a bad wire or coil. The other question you should ask yourself is "Did the engine speed drop substantially when I disconnected the wire?" If yes then the associated cylinder meets the criterion for combustion, which includes fuel, spark compression, and all three at the correct time (if the timing were off on any of the three it could miss occasionally, all the time, or could result in abnormal combustion). If not, one or possibly more of the aforementioned requirements have failed or partially failed. Possibilities include bad and/or improperly gapped spark plug, failed fuel injector or associated wiring, more serious engine problems such as a bad head gasket or burnt valves (no compression).

Try that and see what you come up with, then you can diagnose fuel problems.