1992 LT1 Coupe, 102k mi - Blew the upper, rear radiator hose yesterday. Of course, it sprayed onto the belt, so coolant went everywhere - including soaking the opti. The good: It happened in the driveway. The bad: Now it won't start so I can back it into the garage.

Question: Is there hope of it drying out, or should I just replace the opti while I'm at it? The current opti is believed to be the original one.

 

Was that the original opti?

 

As far as I know, it is the original Opti. The previous owner had the car for 10 years and didn't replace the Opti, even though he replaced the water pump.

 

I had the same thing happen to me a few years ago. I was on the highway doing 70 when it blew, killed the car immediately.

After fixing the hose it wouldn't start. Right before giving up and ordering a new opti, I checked the coil wire and put some dielectric grease on it, and it fired right up.

My thought would be to check all those wire connections, make sure they are dry and put some dielectric grease on them, see what happens.

When my blew, coolant did get everywhere, but the serp belt actually seems to direct most of it away from the opti. The opti is also a sealed unit, so unles sit were completely submerged, it probably didn't get all that wet. But who knows, strange things happen.

As far as replacement, I would take the old one out first and inspect it. The optical sensor in it may be perfectly fine, and it is the best you'll find as far as quality. You may just need a little clean up and a fresh cap and rotor, depending on seals and bearings.

 

I have successfully cleaned the optical sensor with brake cleaner, followed by a couple kleenex tissues folded and pulled through the slot.

 

I would try using like a small diameter wooden dowel, wrap some bandage gauze around it and clean each opening, maybe spray a little electrical cleaner on the gauze. Most of the time I use brake cleaner not the oily environmental stuff as it cleans and evaporates, than replace wires using dielectric grease which will help keep out moisture on the boot too!

 

So, I removed the coil wire from the coil and opti. Cleaned with carb cleaner. Dried with compressed air. Reattached with dielectric grease. Repeated on all spark plug wires on opti. I also did the same procedure on the coil connectors.

Still no start. Note: I didn't refill the coolant, because I didn't want to have to drain it and remove hoses if the opti was going to need replacing. I'm just hoping to get it to fire up and shut it down before installing the new hoses and refilling.

Is opti removal next?

 

Not yet...

If it were me, I would check a couple of other things first.

First I would unplug the opti harness from the opti, and check for coolant seepage at the connector.

If that was dry, then I would get a spark tester and follow the path. First the plugs, then the connection to the opti, then the coil. If you have no spark at the plugs, but spark into the opti, then the opti is bad. But, if you don't have spark into the opti, and have spark at the coil, then the wire is bad. If you don't have spark at the coil, have the ICM checked. If it's good and no spark, then volt test the opti harness.

This is where the system gets tricky. The opti sensor sends the signal to the ecm which sends signal to the icm and injectors, which times the coil (icm). The coil sends spark to the opti distributor which fires the plugs. the distributor side of the opti is a classic distributor.

It's really up to you at this point and either way has advantages. If you don't really want to put it all back together and test individual components, only to find the opti is bad, then just go ahead and replace the opti, w/ new harness, coil and icm, etc. It will cost more (maybe), you won't know for certain what the issue was, but you'll have new parts and regardless of the issue, it was probably covered.

Or you can take the time to put it together, and diagnose the system. You may find the the issue was, for example, the ICM $80 and 15 min. or the harness connection, $50 and 10 min. But you still have the old opti, which may go another 100K or may crap out tomorrow.

If I had time and money, I would refresh the parts and be done with it. However, if time and money were tight, then diagnosis is the answer.

 

Thanks! Will clean and dry the opti harness first, duh. Then test for spark at the plugs and opti (via wire from coil I assume). Then see what happens.

 

Did the ignition control module get wet? If so, pull the connector and clean, dry the contacts. You may have fried it though....checking for spark will tell you for sure.

 

Do you have access to a scan tool? If so, plug it in, crank the engine, and look at RPM. IF you see RPM while cranking, Opti is not bad. If no RPM, optical sensor isn't not functioning -probably wet and/or dirty from the water. You CAN clean these, but only worth it if the bearing is still good.

 

Same thing happened to me but it was a pinhole link. Luckily I found the problem as I was parked in front of the house. Bought a new opti but postponed the repair. A month later it started right up. Guess it had dried out.

 

I put a spark tester on the coil wire and it did not fire. So, no spark to opti. Pulled the ICM harness, sprayed with carb cleaner, dried with compressed air. No start.

It would seem to be the ICM, coil or (please, not be) the ECM.

Not sure how to diagnose the ICM or coil. My FSM reads like Greek to me when it comes to electronics.

Thanks for your help!

 

How did you come to that conclusion? How did you determine that it's not the Opti??

ICM, take it to Autozone and have it tested.

Coil, put a spark tester on it (or lay the wire near ground). Charge w/12v, then cut the power. Should throw a spark.


Do you have access to a scan tool? If so, plug it in, crank the engine, and look at RPM. IF you see RPM while cranking, Opti is not bad. If no RPM, optical sensor isn't not functioning -probably wet and/or dirty from the water. You CAN clean these, but only worth it if the bearing is still good.

 

Put a spark tester on the coil wire to opti and there was no spark to opti. No scan tool available.

Will take ICM to Autozone for test this week.

 

Check fuses.

 

Well that didn't prove anything except that your cap, rotor, and wires may still be good (likely are).

The ignition signal originates in the distributor (of all cars). Whether you have points, HEI, or OPTI, the process starts there. Some device is needed to tell the system "now" when the crank (and cam) are in the right place.
In a points ignition system, that is accomplished with the points opening. That is the "now" and when the points open, the field collapses in the coil and it shoots a spark out. Spark goes to the rotor and then to which ever cylinder the rotor is pointed at the respective post in the cap.

W/HEI, the points are solid state. The "now" is generated by the pick-up coil inside the distributor. This signal is also used by the ECM to time injector firing. The ECM modifies that to control timing, and sends that signal to the ICM (Ignition Control Module) which is what physically cuts the power to the coil, causing the field to collapse and throw a spark. Spark goes to the rotor and then to which ever cylinder the rotor is pointed at the respective post in the cap.

In Opti, the optical sensors and disk wheel are what create the "now" for the ECM. This signal is also used by the ECM to time injector firing. The ECM modifies that to control timing, and sends that signal to the ICM which is what physically cuts the power to the coil, causing the field to collapse and throw a spark. Spark goes to the rotor and then to which ever cylinder the rotor is pointed at the respective post in the cap -just like HEI,

So, by proving that you have no spark out the coil wire, all you've PROVEN, is that the Opti,ECM, ICM, Coil, or harness//connectors may be the root problem, and that your cap and rotor are not likely a problem.

You need to perform tests that are conclusive. The Coil wire test could have been; if you HAD spark from the coil wire, that would mean that everything prior to the coil was working, and your problem was after the coil (cap/rotor/wires).

In lieu of a scan tool, try putting a fuel pressure gauge on it, charge the fuel, then pull the fuel pump fuse. Crank then engine. If fuel pressure drops off fast w/cranking, the injectors have to be firing....Opti would have to be working and your problem would be narrowed to the ICM, coil or wiring for those components.

 

Took ICM to Advance Auto for test and they confirmed it was fine. So, bought a new coil and crossed my fingers. All fuses intact. All connections have been cleaned, dried and lubed with dielectric grease.

No start.

It would seem I'm down to opti, ECM or wiring. The ECM didn't get wet. Every significant wiring connection has been cleaned and dried.

The fuel pump test I can do if I can borrow a pressure gauge. I guess that's next.

Thanks for hanging with me and helping me work thru this.

 

No prob. Thanks for sticking to the project and working through it.

At this point, the most likely item is the Opti. If you don't mind the labor, you could prove it by removing the opti, and with it removed, plug it back into it's harness and spin it by hand w/the key on...much as I did with mine in this video here:



If that provokes the fuel pump, injectors, air pump, etc. to run (as if the car were running) then it's still good. If not, then it's dead and you can spend your money on a new one, faithful that it will solve your issue.

 

The opti isn't too big of a deal at this point since this all started with a blown radiator hose and the hoses are all off and the coolant is drained. All that's left is to remove the water pump.