Jcastro2333

I just bought a 93 firebird formula with 86,000 miles on it and it randomly shuts off when I drive it. The first few days I had no issue then now out of a sudden car will randomly shut off after a short time of driving. The times that this has happen to me time varies before I can start the car up again some times I can start it again instantly sometime it takes 20 mins to a hour before I can. I haven't noticed anything wrong with the car driving wise it will drive good then just shut off randomly. Anybody have any idea what could be going on?

Jcastro2333

Sorry forgot the mention I texted the previous owner and he said he did put a brand new ICM.

DelSoto

Does the ses light come on?

Jcastro2333

No it does not.

DelSoto

Does the SES light cycle on when you first start the car (indicating the bulb works).

Jcastro2333

I'm not completely sure I believe I have seen the ses light when I first start the car but I will make sure in the morning can that indicate something?

DelSoto

Yes....that the light works. Without trouble codes as reference these are just guesses. Coil...Opti...fuel pump....icm (but you have that covered of course I have seen fresh ones fail and considering it was replaced recently, it may be suspect). Maybe throw a fuel pressure gauge in the trunk ...also spark tester. When you get a shutdown with no restart, check for fuel and spark. If you do see SES light, check for trouble codes.

Jcastro2333

K I will check in the morning to make sure that light does come on. Thank you for the info.

maybe2fast

check coil plugs, just ran into this. One of the tabs on the coil were broken and not holding the gray plug on the coil tightly.

Fatdog2

Since nobody chimed in today this sounds like the crank sensor going south.If it's not fuel related(and you have changed the fuel filter)well previous posts years ago said this could be the problem.Or one of the wires connecting to the opti.With all this guess work,I would take the car to a mechanic and have the car diagnosed .Hope this helps.(please don't go to the dealer as the new mechanics don't have a clue about these cars unless it throws a light on the dash.)My02.

Injuneer

There is no crank position sensor on a 93 LT1. The crank sensor was added in 96, but only for OBD-2 misfire detection. Possibly you meant cam position sensor.

Check for codes. DTC 16 for the optical cam position sensor in the Optispark distributor will shut down the fuel system. DTC 16 does not turn on the SES light. The cam position sensor is susceptible to heat soak, as is the ICM and the fuel pump. Might be worth having the ICM tested, even if it is supposed to be new. Make sure they repeat the test several times to get it hot.

Fatdog2

That's where I'm confused with the ICM testing.When you take it off the car,it cools down to cold when you drive the thing over there.So when Autozone or another place checks it,it's cold.Doesn't the thing have to get hot for this test.And how does a person get it hot for the test?Hope I'm not steppin over bounds here.Manny thanks.

Injuneer

I've also heard of people taking a hair dryer with them to use to heat the ICM up while testing.

Fatdog2

Ahhhhh.Many thanks.Hair dryer.Of course.

Jcastro2333

Just wanted to give you guys the update I replaced my optispark and it resolved my issue.