HELP!

I have a 93 LT1 that quit on me a few days ago. The car just turned over 30K miles and, I replaced the Opti about 4k miles ago. The engine is bone stock.

I've searched previous threads and found a lot of discussion but, still need some help before I start throwing parts. The car is at home - now - and won't start so, taking it in for diagnostics is not a viable option.

It was a cool day - for North Texas - and 10 minutes into a short shopping trip, the car died at a red light as though I had turned the ignition off. After cranking for about 30 seconds, it fired up and ran normally. On the way back to my office a little while later, it died while going down the street at about 45 mph - again - just as though I had turned off the ignition. After coasting to a stop, it started again and ran normally. On the way home later that afternoon it went through the die/start twice more at about 5 mile intervals. The third time it died and will not start. I ended up having it trucked home on a flat-bed.

I don't have the diagnostic equipment - nor skill - to look for codes.
I've looked and not found any loose or corroded wires around the ICM.

I'm not sure it is relevant but, for a few weeks prior to it quiting, I noticed that it would idle at about 1100/1200 RPM when I came to a stop but, I could blip the throttle and it would settle down to the correct 700/800RPM idle. At the time, I thought it was probably mechanical binding in the linkage - now, I'm not so sure.

Any constructive suggestions will be sincerely appreciated.

Thanks

Les

 

Going to have to read those codes ! Just takes a paper clip to do it and the code reading guide should be in a sticky .
There are several novice things you can do but a friend with mechanical knowledge and a garage full of tools is a blessing.
No way should you have needed a Opti with 30,000 miles unless it got hosed down with water .

Have someone turn key on while you listen with gas cap off for fuel pump to come on.

take coil wire off and lay it where you can see it arc to coil. Should be able yo hear it poping.

At night have someone turn the engine over and look for sparks from all wires around the front of the engine.

Also note is your security light flashing when it won't start.

Check your water level and feel under Water Pump for a drip down onto OPTI .

 

Larry00 is giving you good, sound advice. It would be very beneficial for you to aquire a good scanner, (not just a code reader) as sometimes failures don't induce codes, however they can often be observed in the live data stream. A good freind with a scanner and knowledge about the subject matter would be even better.

Jack.

 

[QUOTE=larry00;1576259222]No way should you have needed a Opti with 30,000 miles unless it got hosed down with water. QUOTE]

Guilty! I bought the Ruby from the original owner this past Spring and it is pristine but, the engine had 18 years of accumulated grime on it. I knew I shouldn't get the Opti wet but, I couldn't figure any other way to get the engine really clean. I guess it was worth it. We've done four shows and placed or won three times.

Larry and Jack, thank you for you input. Between your advice and the other threads it lead me to, I think I can determine what the problem is. I'm tied up with a family funeral for a few days but, when I get that behind me, I'll find the problem and get it fixed. I'll post the results.

Thanks again for your help.

Merry Christmas

Les

 

Les I live in Flower Mound and have a 93 Coupe as well. Be glad to try to help you troubleshoot this if you'd like.

 

Just sent personal message.

 

I threw an ICM at it - no joy. Checked and am getting no spark when turning it over. The fuel pump runs when you turn the ignition on and I can smell fuel from the spark plug hole when turning the engine over with he spark plug removed. So, it's apparently getting fuel but no spark.

 

Did you pull the codes?
http://forums.corvetteforum.com/c4-t...63284-sys.html

 

No start fault finding
http://www.mainstreamtopics.com/foru...p?showtopic=78

 

Here are a few tests to get you started on the problem. Be the utmost of careful not to short anything to ground. IGN key off, remove ignition module connector and check the ground connection on pin C - BLK/WHT wire, (resistance about 0) .

All readings made with referance to ground.

Check for voltage that supplies coil, Coil power test -12.0 VDC (battery voltage)
Next, “Key on”, check for 12 volts at pin A - PNK /BLK wire and pin D – Dark green wire. If no voltage check the coil fuse 10A, (#25), or wiring.

If all is good, set meter to read AC volts and connect probe to terminal B – white wire. Have someone crank engine, meter reading should be between 1 to 4 volts AC. Key off! Put connector back on. If OK, this indicates opti and ECM are probably working. If not, opti or ECM could be source of problem. If all is good, the IGN coil could be the problem since you said the ICM is new.

If you don’t get the AC voltage at pin B, a bad connection at opti or ECM or dirty connector are possibilities as well……..Now having said that you said you are getting fuel to the cylinders via the injectors. If that is true then it is reasonable to assume the opti is working because the low resolution pulses from the opti are required to drive the ECM to produce the drive for the injectors. (However I would like to know for sure if the injectors are working by use of a noid light).

Now if you do have drive to the injectors and no drive to the ICM , then it looks like that part ECM that drives the ICM is not putting out a signal hence the ECM could be bad.

Make these tests and you should have a better direction of what to look for. Report back for additional information if required.

You should be checking for spark off the coil rather than off the plug wires.

I don’t believe codes are going to get the car fixed but can serve as back up information to confirm a belief. You need to do testing and troubleshooting to resolve this problem.

Do you have any documentation or repair books for the car?

 

Check for power to coil, my coil failed on me(AC Delco). The coil was loose inside the housing.

I will look in my FSM tonight and give you all the checks.

I would get a FSM, it will save you a ton of money and time.

 

All in the link I posted above if the OP cares to read it
http://www.mainstreamtopics.com/foru...p?showtopic=78