simple

brothers car, only mods are catback, cold air and Walbro fuel pump. auto trans


car will start and run for approximately 3-4min and then just shut off. we then have too wait a min or 2 before it will start again
no starting problems other then when it shuts off after the 3-4min of running

any ideas on what i need too start looking at?

lt4 fd

Maybe a dumb guess but maybe there is something going very wrong when it trys to start running in closed loop...?

indieaz

If you are able to scan it that would be of great help. Maybe the fuel pump is cutting out? Does it die slowly and sputter out or shut off very quickly - as if the key was turned off?

RE: CLOSED LOOP - You could always unplug the O2 sensors to force it to open loop and see what it does. I can't see how that could cut the engine off entirely. Sounds like ignition modele or something is suddenly going 'off' - possibly a loose connections somewhere? Check that and make sure a solid conneciton exists between opti and ignition coil.

simple

yeah, i think it has something to do with closed loop activation

it just turns right off, no puttering no petering out. just straight shuts off like keying it off with the ignition. thats why i rule out the fuel pump, we had the stuttering and slowly petering out problem before. the new Walbro pump cured that

how is the ICM affected by closed loop? (if it is)

he had it scanned at a dealership and is picking it up tomorrow and should be getting a print out of what is going on with it. more info will be available then

keep it coming fellas
thanks alot

simple

ignition switch maybe in the column?

indieaz

ICM isn't affected by closed loop at all. In closed loop the copmuter simply refers to new fuel tables and uses O2 sensor feedback.

Possible loose connection, verify your ignition wire in the fuse box in the driver door is solidly connected too.

The best thing you could do though it get it scanned if possible, then we can read the log and see exactly what happens when it shuts down.

97WS6SCharged

I wouldn't totally rule out the ICM. Since it's attached to the head, it will heat up quite a bit after a few minutes. If it's old it may be shorting out when it gets hot. Could also be the coil since it's in the same location. I would tend to rule out the computer since you didn't mention any programming changes to the car. You could try swapping with another car if you believe it is suspect, same for the ICM and coil.

97s10ondubs

My car did that when the opti died, except it ran a lil longer maybe 5-10 min, until it would get hot then shut off like you shut the key off, but if you let it cool off it would start again and drive a lil longer then die again. The opti does weird things and it seems a lot of ppl have different symptoms from it.