I have a no start issue on my 1992 lt1 coupe. Security message on, asr lite on, Cranks fires momentarly 1st try, Cranks but no fire 2nd time. Always starts cold, the asr lite and security message comes on after it has been driven and then the no start condition occures let it sit for about 3-5 minutes and it will usually start but it runs rough at first. I have replaced the ecm and the key lock cylinder and the key. I have also disconnected the asr to see if that changes things but it doesnt. the only code I get is for a right bank o2sensor. Any help? Thanks Chuck

What's the "description" of the code for the O2 sensor---is it a rich or lean code? How does it run/performance/idle when it is running?

Its been awhile since I looked at the car, I beleive I was getting zero milivolts reading from the o2 sensor. Sometimes the engine will race on start up, like the air idle control motor is stuck open, I think its doing this because its getting a signal from the ecm to do it. The air idle control motor seems to work fine other wise. I have the factory repair  manuals for my car and have read them a bunch, they dont go into much detail about the anti theft deterrent system. My car has been to the gm garage for this problem and thats how it ended up with the ecm and key cylinder  replaced. Replacing those parts didnt help. I have a new opti spark distributor waiting to be put in next. The car has about 55000 miles. Thanks Chuck

the iac is closed on a cold start ( i am almost positive) as that is like the choke on a carb. this may sound nutty but you may want to replace the engine temperature sender. knew someone that had a lot of problems and spent a lot of money trying to fix it and one garage changed the sender and car was fine. the garage felt so bad all they charged him for was the sender. they said that no one ever thinks about that. 

VATS (anti theft) does two things  A) grounds the starter relay allowing the starter to engage and B) sends a 5 volt pulsed/modulated reference signal to the ECM which in turn pulses the fuel injectors if and only if it gets the reference signal. I'd check it this way---when it will not start connect a noid light to a couple different injector connectors and see if you have pulse(light blinking) while cranking. If you don't there is a seperate "decoder module" for VATS which allows starter to engage and send the reference voltage to the ECM. Could be a internal problem w/decoder module allowing starter to engage and NOT sending reference signal to the ECM OR the wiring/connectors or terminals between the decoder module OR I may be way off in left field ---I'm basing this WAG on the fact that you have a security light on and a no start. None of the above would exlpain the ASR light or O2 sensor code---as Dave said the O2 itself may be bad or that bank may be lean (vacuum leak/bad injectors) Low voltage from a O2 sensor COULD be the response of a good O2 when it sees a lean condition.

Its not the security lite that comes on, it is the message center that gives the security sys message and only after the asr lite comes on. Do you know where the decorder module would be located? I didnt see much in the factory manual about the message center I am wondering if the IPC is part of the vats decoder. I had a Caddillac that had to have the instrument cluster replaced because when it got hot the car wouldnt start

The decoder module is  integrated into the CCM (central control module)---which is behind the I/P cluster. I'll say this once more to clarify---I would only go there IF I had no injector pulse while the starter is engaged-- because in my mind the ECM has been eliminated as a possibility-since it's been replaced.

it maybe possible to have gotten a defective ecm. i know i ordered one thru gm and when the car started it would give me codes with nothing wrong. changed out the ecm from a different supplier and had no trouble. just a thought here.