Cleaning the Optispark??

[1on2off]

Hi, Guys and Girls. This is my first posting re: a problem with my '94 Coupe. It's been stored for about the last 6 months and I just put it back on the road to move to my new home. Started great and then parked it outside the garage while I went for insurance and reg. It poured that night when I went over to get it to bring it to my lift to change oil, etc. Started fine, again, but stalled about a block later. Hard to restart but got it home. Took it to the garage next morning to have the SES light decoded. My buddy told me a code 36, bad Opti. I brought it back home to regroup and look for a unit on the internet. I've been reading as much as I can and I'm 'Optied' out. Here's a question, is it possible to pull the cap and rotor from underneath without going through the whole Opti disassembly procedure? Is it possible I just have a cap/rotor problem or almost certainly a new unit? Right now, the car will always start after exactly 5 seconds of cranking and seems to run real strong, although both cooling fans come on right after it starts. I was told it's running in limp mode but the way the car runs seems to defy that reasoning. BTW, the engine in the car only has 27k on it and paperwork from the original owner shows a second Opti installed that now should have only 9-10k on it. Another question, how bad can the Opti be if the car starts and runs at all? I've heard most times that the car just shuts down and that's it. Sorry to be lengthy but I wanted to get all my points across. Ed.

 

[gmjunkie]

Hi, Guys and Girls. This is my first posting re: a problem with my '94 Coupe. It's been stored for about the last 6 months and I just put it back on the road to move to my new home. Started great and then parked it outside the garage while I went for insurance and reg. It poured that night when I went over to get it to bring it to my lift to change oil, etc. Started fine, again, but stalled about a block later. Hard to restart but got it home. Took it to the garage next morning to have the SES light decoded. My buddy told me a code 36, bad Opti. I brought it back home to regroup and look for a unit on the internet. I've been reading as much as I can and I'm 'Optied' out. Here's a question, is it possible to pull the cap and rotor from underneath without going through the whole Opti disassembly procedure? Is it possible I just have a cap/rotor problem or almost certainly a new unit? Right now, the car will always start after exactly 5 seconds of cranking and seems to run real strong, although both cooling fans come on right after it starts. I was told it's running in limp mode but the way the car runs seems to defy that reasoning. BTW, the engine in the car only has 27k on it and paperwork from the original owner shows a second Opti installed that now should have only 9-10k on it. Another question, how bad can the Opti be if the car starts and runs at all? I've heard most times that the car just shuts down and that's it. Sorry to be lengthy but I wanted to get all my points across. Ed.

First Off,Welcome to

And Second, there are several things that can throw a code 36!!! My guess it won't be the Opti!! Yeah, I've heard all the Horror stories about the Opti Spark but truth is in Many,Many years and several 100,000 miles,Lots and Lots of Washing Engines, and repair of 100's of vehicles with supposedly Opti problems,
I've only had to replace 1,and that was No Fault of the Opti!(Big,Big Oak Tree at 60 down the Middle!!) There are several things that can cause the problems your having,but without proper tests and equipment for diagnoses it will be hard to figure out!! It seems to be the norm here in Western NC to throw Expensive parts at till you find it,Even at the Dealerships!! I just repaired one about 2 months ago that had been to 2 Independent Shops and 1 Dealership (Over a Thousand $$)and wasn't repaired yet,it took me 2 days but I found a Hot Connection pin in a wiring plug and was loosing contact after running for a while!! PS Don't get me wrong,I'm sure that like anything Electronic,Opti's do go bad specially with several 100,000 being used on cars,but I bet that there have been more replaced that weren't because of some other problem!!

 

[jmccloud]

Slow start and dies often

Welcome, this is a great place. And congrats on Corvette ownership.
Your symptoms (especially having just taken your Corvette from storage) sound much more like a clogged fuel filter. Or slightly worse, a weak fuel pump. Doing a search for either using the tab above will yield lots of information; suggestions for changing the filter without putting gas all over the place, how to measure fuel pressure and diagnose leaky injectors, weak pumps, etc.
And keep checking the codes. Are you sure you accessed all of them? Search on this subject too as Corvettes have more places to look for codes than most OBD I cars.
If you can't find this info, come back and ask for more help.
And please post when you do find the solution.

 

[LT4man]

Welcome to the

In reply to your question about accessing the Opti from below. No, not possible. The water pump and the crankshaft pulley need to be removed in order to work on the Opti. Even if you just replace the distributor cap and rotor, the same amount of disassembly needs to be done. I replaced my cap & rotor with an Accel cap & rotor at the beginning of summer this year.

What junk says is so true! Most Opti replacements are misdiagnosed. I will bet along with him that your issue lies somewhere else.

Make sure you have obtained ALL codes.

SAVE THE

 

[John Robinson]

Welcome to the CAC

I am sending you this information just so you will have a better understanding of how the fuel delivery from the ECM works.

Throttle Position Sensor (TPS)

Copied from 1993 Service Manual
​

The Throttle Position sensor (TPS) is a potentiometer connected to the throttle shaft on the throttle body. It is a potentiometer with one end connected to 5 volts from the ECM and the other to ECM ground. A third wire is connected to the ECM to measure the voltage from the TP sensor. As the throttle valve angle is changed (accelerator pedal moved), the voltage output of the TP sensor also changes. At a closed throttle position, the voltage output of the TP sensor is low (approximately .5 volt). As the throttle valve opens, the output voltage should be approximately 5 volts.

By monitoring the output voltage from the TP sensor, the ECM can determine fuel delivery based on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent burst of fuel from the injectors and cause an unstable idle, because the ECM detects the throttle is moving.

If the TP sensor circuit is open, the ECM will set a DTC 22. If the TP sensor circuit is shorted a DTC 21 will be set. A problem in any of the TP sensor circuits will set either a DTC 21 or 22. Once a DTC is set, the ECM will use a default value for TP sensor, and some vehicle performance will return.

A personal note, when my TPS failed it DID NOT set a code other than to tell me the ECM was bad.




Just as others have said the opti gets a lot of bad press. My car stopped running and I costed into a mechanic I knew his first comment was bad opti. I then had the car towed to another garage and they came up with the ECM was bad so we put a new one on the car. Car still did not run and finally we found the TPS was bad and telling the ECM to shut off the fuel to the injectors.

 

[badabing9]

my understanding is that if you "clean up" the optispark a parts house will "clean out" your wallet in the purchase of a new unit as these are not meant to be wet.

 

[Red Vette]

I agree with Gregory and Junk, it probably isn't the Opti. However, if it is, replace the water pump when you replace the distributor cap and rotor, even if the pump is not leaking now. It's an even bet that the water pump will start leaking after you reinstall the old one, and you will have to remove them all again. Hopefully, your problems are not the Opti.
Barrett

 

[1on2off]

I've been away for a few days, guys, thanks for all the answers. Right now my car is still in upstate NY and I'm debating about how to get it down here to work on or letting somebody up there try to fix it but as you all agree on a lot of 'mechanics' are just parts replacers. Junkie, I notice you're listing Old Fort in your profile. I'm not far from there at all. Can I send you an e-mail or something to talk about this sometime?? Again, great responses in a very short time, thanks. I'll be back shortly.

 

[Robertwav1]

Is this thread similiar to the ones that had a bad injector causing this problem? No cost for checking injector ohms. Thought I'd mention that if it does indeed apply to this year vehicle. Codes are so misleading at times especially with the 1st generation computers. Check all vacuum lines also, doesn't cost anything. Vacuum leaks are notorious for engine codes.

 

[gmjunkie]

I've been away for a few days, guys, thanks for all the answers. Right now my car is still in upstate NY and I'm debating about how to get it down here to work on or letting somebody up there try to fix it but as you all agree on a lot of 'mechanics' are just parts replacers. Junkie, I notice you're listing Old Fort in your profile. I'm not far from there at all. Can I send you an e-mail or something to talk about this sometime?? Again, great responses in a very short time, thanks. I'll be back shortly.

Yes,I know exactly where Tryon NC is !! I Go through there quite often on my way to GSAA,it's about 45 miles strait south of me through some of the most Beautiful and Fun roads in Western NC!!You can e-mail me at gmjunkie@charter.net or you can Call me Toll Free 1-877-677-2984 ext 1,2, or 5 I'm in and out allot, but check messages frequently!!Leave a message if I don't answer,sometimes I'm under a Car,after Parts or at a Auto Action!!

 

[LT4man]

Check all vacuum lines also, doesn't cost anything. Vacuum leaks are notorious for engine codes.

So very true! I still have my first vacuum gauge from 1974! A good technician's best friend. One can tell so many things from looking at the vacuum of an engine.

SAVE THE