92 LT-1 Intermittent Start/Run
Thread Starter
8th Gear
Joined: Dec 2007
Posts: 8
Likes: 0
92 LT-1 Intermittent Start/Run
I have a 92 LT-1 that I've run for about 10 years now. I replaced the Opti about 3K miles ago, car was running good. I did notice that the backlighting/contrast on the instrument cluster hasn't been working properly for a couple of years. Displays are still there but dim and hard to read. Car lately has been keeping a fairly high idle even in closed loop. The problem I have now is starts up fine cold, but after 2-3 minutes at idle (temp still very low, maybe 120 or so) dies and won't start. If I floor it and crank sometimes it will start with a lot of smoke but then won't idle at all. If I let it sit and completely cool down it restarts easily but then does the same thing. I've had this intermittently in the past but now it seems to be a constant thing. The last time I actually drove it was a hot day. I limped home at idle and about 40 MPH and it was running a lot hotter than normal. There were no codes at all during any of these times.
I'm going to try the fuel filter and check pump pressure first, but I think these are good. Some guys have also mentioned the ignition control module, I've never replaced this. I'm wondering whether it's the ECM given the instrument cluster and overheating without a reason issues. I'm fairly sure the opti is fine. The injectors tested good within a year or so ago. The only other thing I can think of is a dirty throttle body but that usually is for problems starting when cold. Any ideas?
Thanks,
Jerry Barth
I'm going to try the fuel filter and check pump pressure first, but I think these are good. Some guys have also mentioned the ignition control module, I've never replaced this. I'm wondering whether it's the ECM given the instrument cluster and overheating without a reason issues. I'm fairly sure the opti is fine. The injectors tested good within a year or so ago. The only other thing I can think of is a dirty throttle body but that usually is for problems starting when cold. Any ideas?
Thanks,
Jerry Barth
Burning Brakes
Joined: Apr 2009
Posts: 1,185
Likes: 33
From: Charlotte Michigan
I would check the ICM under the coil. It may have lost the heat sink grease causing it to not work correctly when the engine warms up. Surprised it didn't throw a code, but maybe intermittent. Could be a ground wire. Check fsm for further diagnosis.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
I have a 92 LT-1 that I've run for about 10 years now. I replaced the Opti about 3K miles ago, car was running good. I did notice that the backlighting/contrast on the instrument cluster hasn't been working properly for a couple of years. Displays are still there but dim and hard to read. Car lately has been keeping a fairly high idle even in closed loop. The problem I have now is starts up fine cold, but after 2-3 minutes at idle (temp still very low, maybe 120 or so) dies and won't start. If I floor it and crank sometimes it will start with a lot of smoke but then won't idle at all. If I let it sit and completely cool down it restarts easily but then does the same thing. I've had this intermittently in the past but now it seems to be a constant thing. The last time I actually drove it was a hot day. I limped home at idle and about 40 MPH and it was running a lot hotter than normal. There were no codes at all during any of these times.
I'm going to try the fuel filter and check pump pressure first, but I think these are good. Some guys have also mentioned the ignition control module, I've never replaced this. I'm wondering whether it's the ECM given the instrument cluster and overheating without a reason issues. I'm fairly sure the opti is fine. The injectors tested good within a year or so ago. The only other thing I can think of is a dirty throttle body but that usually is for problems starting when cold. Any ideas?
Thanks,
Jerry Barth
I'm going to try the fuel filter and check pump pressure first, but I think these are good. Some guys have also mentioned the ignition control module, I've never replaced this. I'm wondering whether it's the ECM given the instrument cluster and overheating without a reason issues. I'm fairly sure the opti is fine. The injectors tested good within a year or so ago. The only other thing I can think of is a dirty throttle body but that usually is for problems starting when cold. Any ideas?
Thanks,
Jerry Barth
Waiting for the results of you changing the fuel filter and also checking the fuel pressure before I begin offering anything.
DO you have a scanner?????
DUB
Thread Starter
8th Gear
Joined: Dec 2007
Posts: 8
Likes: 0
[QUOTE=DUB;1588042601]Jerry,
Waiting for the results of you changing the fuel filter and also checking the fuel pressure before I begin offering anything.
DO you have a scanner?????
Hi guys,
This is not my everyday driver so I got the parts together off the internet. Got a new ICM and coil. Changed both today, the ICM had no grease or anything behind it. Also lots of grease/dirt on heat sink fins. I cleaned everything off and put new ICM on with computer heat sink compound. The old coil was the original one because I had to drill out the rivets. Car has 140K miles. Put new coolant in and ran it out to end of driveway and back. Then ran it for 30 minutes or so at idle while I put more freon in. No problems like it had before, when stopped it started right up. Haven't driven any distance yet because I'm waiting for the wife to be home so I can get a ride home if it dies on me again. I'll let you know if more stuff comes up but looks like this fixed it.
Thanks for all the help guys, I really love this forum. BTW, tell me how to fix my dim and almost unreadalbe digital dash now, that's the next project. It lights up OK but the numerals have almost no contrast to them.
Thanks,
Jerry Barth
Waiting for the results of you changing the fuel filter and also checking the fuel pressure before I begin offering anything.
DO you have a scanner?????
Hi guys,
This is not my everyday driver so I got the parts together off the internet. Got a new ICM and coil. Changed both today, the ICM had no grease or anything behind it. Also lots of grease/dirt on heat sink fins. I cleaned everything off and put new ICM on with computer heat sink compound. The old coil was the original one because I had to drill out the rivets. Car has 140K miles. Put new coolant in and ran it out to end of driveway and back. Then ran it for 30 minutes or so at idle while I put more freon in. No problems like it had before, when stopped it started right up. Haven't driven any distance yet because I'm waiting for the wife to be home so I can get a ride home if it dies on me again. I'll let you know if more stuff comes up but looks like this fixed it.
Thanks for all the help guys, I really love this forum. BTW, tell me how to fix my dim and almost unreadalbe digital dash now, that's the next project. It lights up OK but the numerals have almost no contrast to them.
Thanks,
Jerry Barth
