luckkky1

Car is a 95 Fleetwood LT1 purchased for my teenager. After several autozone optis , i found a low mile ac delco opti from a very reliable source and replaced it. Put a new waterpump also. Here is where I think the problem is. While I was pouring my coolant into the top of the new waterpump a piece of plastic about about the size of a dime was in the bucket of coolant and into the engine it went(i know this is bad!).
So after taking the waterpump back off to see if i could locate the plastic I guess its in the engine someplace.

Could this piece of plastic cause the car to just shut off? It will start right back up though.

I thought this was an ICM problem because the engine just shuts off with no stumbling once it gets up to temperature between 155-180. So I took a coil and ICM off a working car and ditto.

Other info: this is while at idle, sometimes a code 64 (right o2 sensor)kicks on an the idle drops low for a moment. if I rev the engine its ok and smooth, not like it stumbles for fuel. I hear the fuel pump, but I dont have a fuel pressure guage. Any thoughts or suggestions would be appreciated.

bw_hunter

I think the plastic piece causing the stalling is very unlikely. Just a coincidence...if you can believe that coincidences exist.

I'd look closely at the opti itself. does it through any codes when the car stalls? Look closely at the wiring and connectors...they are getting pretty old. Flex some wires to see if you can force the fault.

Why was a low mile opti taken off in the first place? Unless the car was junked I would find the opti itself suspect...

Good luck!

Chimera96

OP

hopefully the piece of plastic will lodge somewhere in the cooling system where it won't cause any blocking or flow issue. In the future just fill into the reservoir

given the "several" optis and now what you to believe a known good AC Delco and you still have issues it can likely be in the wiring of the 4 pin Opti harness itself or the wires ganged up near the coil where they ground to the head. Carefully wiggle/pull on these wires while motor is running. If it suddenly shuts off or stumbles during any particular tug....look close, even pulling pack flex conduit, for any cracks of the wire insulation.

I chased a failing Opti after several opti replacements to one day find by just touching the wires leading into the long connector that plugs into the top of the opti, the brown wire just pulled out from the crimp. That was certainly a needle in the haystack find

these cars are now 20+ years old. wiring gets old & brittle especially after being handled several times for parts replacements

On the 02 code, swap 02's up front. If code goes to the other bank you know it is a bad sensor. 02's are a wear item and do need replacing. replace with AC Delco only and do so in pairs

luckkky1

Thanks for the input. Just got a fuel pressure gauge from harbor freight. Fuel pressure was at a steady 36 until engine shut off, then it immediately went to 42. I tugged and pulled on all wires coming from the opt and the icm and the coil and couldnt get it to shut off. It seems when Im looking at the scanner it will shut off when it gets in the temperature range 155-180. It shuts off just as it would shut off if you turn the ignition switch off or pull the icm plug off. There is no stutter or stumble like it was starving for fuel.
Could this be the PCM, ignition switch, a bad ground when the temp moves the metal? Any input is appreciated.

Chimera96

the ICM (ignition control module) could be the problem. Heat can affect them. They often test OK on the bench but when they get hot they stop working

if replacing get some heat putty, most auto part stores have it, and put it on the back of it when you mount it. The stock one would also have had the putty behind it.

some even stand off the ICM bracket from the head with 1/4" spacers

Fatdog2

I used Shoebox's site for my ICM spacers.Go to How to's on his site then go to #30.Shows how to do this.hope this helps.