LT1 trouble codes. Optispark

**dunebound69** · 06-25-2009, 02:44 PM

Car strated missing after being stored over the winter scaned for codes and got 5

11- Malfunction Indicator Lamp Circu Porblem
16 - Ign System Problem loss of low res pulse signal
29- Output Driven Module (ODM) Fault EAS circuit
32- EGR Dianostic SW, Signaling Inccorect EGR Valve Operation
51- ECM PROM error

I am thinking the no check engine light is #11
16 is optispark is shot, 29 is optispark as well. 32 New EGR needed. 52 hopfully cleared with optispark replacement. Any help welcome. The car runs fine till you load it or get on it. Then it just belches and farts. Let off and it idles, running a little rich.

**95kdw** · 07-19-2009, 10:23 AM

I had some what similar problem with my 95 lt1, Went to start it after being stored over the winter, started missing like the timing was off and would just die. don't remember the codes but I ended up replacing the optispark ( complete distributor ) and the EGR. Has been running great since.

**dunebound69** · 07-20-2009, 05:12 AM

Pulled the h2o pump and opti last night, h2o pump had the classic leak guessing it is the opti will order parts today and post when it is back in. Going to do some seal at the same time greasy mess down there.

**Zapper2003** · 08-12-2009, 07:19 PM

How'd you ever make out?

**dunebound69** · 08-13-2009, 04:42 AM

Ended up doing the Opti with a GM performance parts from Summit plus the GMP H2O pump. Looks like the water pump had been leaking on the opti. I have not rechecked the codes yet. (Brother borrowed my scanner). Spent 16-20 hrs on this repair. Could not believe the car did not over heat, the rad and ac condenser were so full of crap. I did a bunch of other while I'm at it things. Getting the little internal spline coupler off was a bitch. Water got in there and rusted. Found getting the air out of the cooling system to be a pain. Spent a 1/2 hour filling it venting out the vents, looked like all was good. Drove to work the next morning, low coolant light comes on. Added 2 quarts to the rad. Seems to be running good but may still be a little rich. Put in a Trick air elbow to get rid of that elephant dick thing GM put in there. Next big job is a major brake job on the rear. Previous owner did a hack job back there. I know it needs rotors, pads, bearings back there. Noise could just be the rotors but the bearings aren't much and 80,000 miles say just do them. Not to mention I am sure the diff oil has never been changed.

**seppburgh** · 08-16-2009, 09:40 AM

Originally Posted by dunebound69

Ended up doing the Opti with a GM performance parts from Summit plus the GMP H2O pump. Looks like the water pump had been leaking on the opti. I have not rechecked the codes yet. (Brother borrowed my scanner). Spent 16-20 hrs on this repair. Could not believe the car did not over heat, the rad and ac condenser were so full of crap. I did a bunch of other while I'm at it things. Getting the little internal spline coupler off was a bitch. Water got in there and rusted. Found getting the air out of the cooling system to be a pain. Spent a 1/2 hour filling it venting out the vents, looked like all was good. Drove to work the next morning, low coolant light comes on. Added 2 quarts to the rad. Seems to be running good but may still be a little rich. Put in a Trick air elbow to get rid of that elephant dick thing GM put in there. Next big job is a major brake job on the rear. Previous owner did a hack job back there. I know it needs rotors, pads, bearings back there. Noise could just be the rotors but the bearings aren't much and 80,000 miles say just do them. Not to mention I am sure the diff oil has never been changed.

I picked up a new GM collent pump last week just to have an OEM unit for when that times come. Dealer price was $ 400. It comes as a kit with all seals. However, the Thermastat is a separate unit along with the seal. This way I KNOW they will bolt right up when the time comes.