10-4. Only difference with my symptons is that the hard start exists when hot or cold.

I checked the wiring from the opti connector to the first connector under the fuel rail cover and it's OK.

I have a FSM but I'm having a hard time finding the correct trouble shooting flow cahrt for a code 36. If anyone can direct me, please chime in.

The specs on my DVM lists input impedence of 1 meg Ohm. I assume this is what you referred to as being not sensitive enough; ie, 10 meg Ohm. Am I correct?

 

You need a 10 meg meter to do voltage checks on digital circuits, or you could blow the ECM. A 1 meg meter will "overload" the integrated circuits. P.S. Code 36 and DTC36 are different. You have DTC36

 

Today I took my PCM and ICM to Oreilly's to run their test. They (nor Advance Auto Parts) can test the PCM.

The ICM test indicated that it is bad.

Question 1) Is it possible that a bad ICM could be causing the PCM to throw erroneous codes as well as cause other driveability issues? For example, both radiator fans come on immediately after starting even when cold and my A/C compressor quit. There is no power to the compressor.

Question 2) Oreilly's and Advance offer a Borg Warner ICM for $105. Ist this a decent unit and price?

 

In the 92 FSM, Code 36 is on p. 6E3-A-70 and 71. Yours may be a different page, but probably the same section. A source for computers is www.autoecms.com. I have dealt with them and been happy with their service.

 

Stranger things have happened, but each code is usually there for a reason. Your AC compressor will not work if there is a fault code in the PCM. Both fans should come on if the AC switch is on, whether the compressor clutch comes on or not. I see new modules on the bay for about 65 bucks buy it now plus shipping. Try Autozone?

 

I failed to mention, the fans come on immediately and stay on with A/C switched off.

I'll check the ebay route, thanks.

Haven't tried Autozone or Napa yet but I'll look them up online. Right now I'm just wondering if anyone knows if these Borg Warner units are reliable.

I'm not about to accept that it's my Opti yet because:

1) It's an AC/Delco unit with 10,000 miles on it & replaced 3 years ago. (Believe me I'm not naive regarding the reliability of these units or parts in general. I'm just not ready to swap it yet in light of #2, read on.)

2) I loose no coolant from my cooling system and I see no other visible contamination in that area.

 

I've got the same problem and just installed a new ICM/coil and she's still dying on me. Works fine cold but after she's warm, dead. I bought an el cheapo Opti for 79 bucks at the bay that lasted maybe 6 months. Bout to buy ac delco one for a nickle then put another nickle VT +3 over BSU that way it's free.

 

Right now I'm just wondering if anyone knows if these Borg Warner units are reliable.

Wells is one of AutoZone's house brands, but who knows? It may be the Borg-Warner units are made by Wells, too.

 

I know it's been a while but here's an update based on a diagnostic done by my closest Chevy Dealer, Coggin Chevrolet, Jacksonville, FL. Two closer Chevy dealers closed since 2008 so I had to take it to them even though it's about 18 miles away but they were very gracious in that they provided me shuttle rides to drop the car off and then to come pick me up when the diagnostic was complete.

I decided to take it to them since I don't know any Corvette specialists and so that's why I defaulted to the stealer. Not something I would normally do but since they are the best authority I can find I took it to them. They said they would do the diagnostic for $99 plus tax. I'm not about to start throwing parts at this problem without a proper diagnostic.

To review; primary problem is CEL with HTC 36. Car runs fine but takes about 5 seconds of cranking before starting. Plus, both radiator fans immediately come on and stay on even when the engine is cold and with the A/C off. My concern was that the problem could be my PCM, not the Optispark. Before I tear into it, I want to be as sure as possible.

I was satisfied with the diagnostic service and follow up Coggin allowed me with the technician who performed the diagnosis. Bottom line:

It's the Opti. Very unlikely the PCM.

He noted that there is oil contamination around the Opti and even claimed with the help of a mirror, that he can see oil contamination leaking from the Opti. I forget now exacty where he said he saw that leakage, mine is the non-vented type, but that's the jist of what he said. (No coolant leak evidensed, I loose no coolant.) According to him, the Optispark units are reliable until something kills them. Like oil or coolant.

He ran through the trouble shooting flow chart on page 6E3-A-83 of the 94 FSM and found that there is power from the PCM to the Opti with 4 to 6 Volts. (I'd post a picture of the page but the forum doesn't allow me attachments.) Anyway, that trouble shooting flow chart ends in the middle box at the bottom of the page that indicates "faulty distributor connector or faulty distributor". My connector looks fine, like new.

Both fans coming on is due to the fault codes being thrown. In addition to the 36, after about a week, the car started throwing HTC 42 and then still later HTC 41.

Total charges = $113. IMO, money well spent.

So I'm gearing up to do a backyard Opti job. I've already seen most of the reports on how to do it including this extremely helpful post by LT*C4.
http://forums.corvetteforum.com/c4-t...-pictures.html

Allow me one lazy question before I go back to researching the Opti purchase: What brand of Opti replacement is recommended for my 94? I remember seeing prices ranging from $200 to $700. What should I expect to pay for a good value unit?

What about the water pump if I decide to replace it. Is a Napa or AZ or Advance Auto WP OK?

Thanks, Rich

 

We sell our units for $114.99 and they have outstanding reviews. Google "chandler motorsports opti." We're celebs over at ls1tech. Otherwise we'll be selling delco units too fairly soon.


This is a dynamic image, latest buyer feedback with our optispark products.

 

Your oil leak is either the seal on the WP shaft or the dreaded intake leak that almost all LT1's get. Yes oil can get into the opti and toss a code 36. You may be able to clean out the opti and seal it with "The Right Stuff" maybe not. The intake leak is not a hard thing to fix all you need is gaskets and again "The Right Stuff" for the front and rear china walls. Take maybe 4hrs and a torque wrench,FSM and the above parts to fix. Reguardless when removing the WP always at least check if not replace the seal on the shaft it is a pain to put in right. The opti seal is easy to do. Once the WP is off you should be able to see where the oil is coming from if it is all over the TC it is the intake if the WP you will see the track from it. Either way make sure you seal the crap out of the next opti

I bought a lifetime Cardone opti for $125 it has some improvements over the Delphi such as the wiring plug area if you look at stock it has a crappy bead of silocon around it that didn't even seal on the last one I bought. The Cardone Signature new(not rebuilt)Has a different type of seal around the wiring plug.It also has brass plug wire connectors instead of aluminum.Good luck.

 

Got one in mine worrks well so far 1k miles on it.

 

Just did a search for DTC 36 on this forum. I'm having the same issues with my 1993 LT1- long starts (6 seconds) and code 36. It's been a month now sense yor last post. Did you change the OPTI or ICM? or was it something else?

 

Thanks. The Chevy technician stressed to me to make sure I change all seals to stop the leak while I'm in there.

I wasn't sure exactly which seals he was talking about but now your post confirms his recommendation. I didn't realize I could be getting an oil leak through the WP shaft.

Please define: 1) "intake leak" and 2) "china walls".

And, are you suggesting that I might be able to remove the cap from the Opti and clean it without changing out the whole unit?

 

I would not try cleaning the opti while it is still on the car there are some little screws(torx) on the rotor and that has to come off the get the plastic cover off to get to the optical sensor/slotted disc which has probably got oil on it. It is best to just put it on a bench and check it out completely. Actually I cannot in good concience recommend just cleaning it unless you just bought it. Most people will flame me for even suggesting it. But if money is tight and you DIY.....

The china walls are the front and rear walls that the intake sits on they have no gasket and you should use Permatex "The Right Stuff" as directed in the FSM along with the intake gaskets when R&Ring the intake. You must put a bead from one side gasket to the other on both the front and rear. Once you pull the intake you will see what I mean.Be carful on reinstall not to move the Permatex drop it straight done and torque according to the FSM.The intake usually leaks at either the front or rear "wall" sometimes both. Good luck