Welcome to the Corvette Forums at the Corvette Action Center!

Optispark or what?

tcxd40

Well-known member
Joined
Mar 7, 2007
Messages
387
Location
Pittsburgh
Corvette
(2) Black '93s, purple '81, '69 vintage racer
Hey guys just picked up another 1993 Vette. This one is a dupilcate of my other '93 except this is an auto. It's for my wife as she keeps complaining about not being able to drive mine.

Bought it, drove it home, and parked it. Started it today, started instantly with no problems. I let it warm up for awhile then took it for a drive, that was short lived as it would not run. Back firing under load, no power in gear, seemd to be missing badly. I read everthing I could find on the optispark system, but nothing on if they crash in an instant.

Question, could the optispark unit die that quickly? It ran great all the way home, about a 1 hour drive.;shrug

tcxd40
 
A lot of times there is no warning .Is the check engine light on? check and make sure the water pump is not seeping . if you have a scan tool check for codes and how the low resolution signal is. How many miles on the vette. Steve
 
Steve

The W/pump is fine not leaking, mileage is 71K, no check engine light. Don't have a scanner either.

What is puzzling is it ran great all the way home. I pushed it a little, run it to about 110 for a 30 seconds or so down the highway.


tcxd40
 
tcx, can you pull codes with a wire on the ODB plug?

First thing that came to my mind, which controls ALL of what you described would be a throttle position sensor. Try to drive it again and see if cruise control will work, if it does not that's another symptom. But try to pull codes. Keep posting as I am very curious.

Paul

And, good luck!
 
Hi Paul,

The sensor was in the back of my mind. Do to the way it is acting just pushed me to the optispark. I'll go to a friend's shop and discuss getting his scanner this week.

I'll keep you posted.

tcxd40
 
The best and most simplest way to test it is if it will not engage cruise control. No tools required.
 
Hey tc, what did you come up with? Does the cruise engage? Inquiring minds want to know.
 
Sounds Familiar

A few things come to mind for you to look at since I just went through the process of fixing a similar problem with my 93 auto.

On mine it would run great until the temperature got to about 180 then it would not pull and back fired and if I would put it in second and hold it there it would start to run above 3000 RPM.

Here is what I did to finally cure my problem.

1. Replaced Plugs

2. Replaced Wires.

Car still had the originals in it at 93K The problem I had did not start until I did this and then I found I had a couple of bad new plugs and I broke a couple of wires while redoing the plugs.

3. I ran car at night and saw that the spark was jumping between the wires and any thing they were close to. (Had spark no Opti Problem)

4. Removed the EGR valve and soaked it in Mr. Clean (or any use Oven cleaner) Because the pintel was not seating. If you spray WD40 or something like that in the cavity around the pintle and it leaks out you have a piece of carbon holding the pintel open. After pricing a new EGR I again soaked it and used dental tools to clean around the pintel seat. I bought two EGR gaskets and then I bought a Stainless grease scatter screen for a frying pan. Cut a piece of the stainless steel screen and put it between the two gaskets over the square opening then.

5. This cured the bad backfires miss problem but I still had a rough idle problem that I cured with a new battery.

After all of this I now have a problem with traction because the car acts like I put 100 extra ponies in it.
 
Well guys here's what is happening.

First, I can not get it to run above 20 -25 MPH, it just sputters, backfires and wants to stall. So I can't get to highway speeds to check the cruise.

Put the scanner on it and it shows no codes. Unfortunately I can not get it in my garage as I have another Vette and a 442 being built. Here in Pa. it's only about 30 degrees alittle cold to work on it outside.

Being John has had good results with his program I will use it as a starting place for mine. All things condsidered, if the optispark unit is bad I would being doing the work that John has had great success with.

More to come.

tcxd40
 
Well, I'm still gonna place my wagers on the TPS.

Hope it would be something that simple for ya.

Best of luck and Merry Christmas!

:thumb
 
Paul,

Yea, the cheaper/simpler the better. I don't mean cheap parts just the fact that it won't cost an arm and a leg to repair.

My first '93 has a history as a former race car so I paid more for it and put alot into it to bring it back. Really don'y want to do that again.

You also have a Merry Christmas and Happy NewYear.

tcxd40
 
I forgot to say that I did a full diagnostic on the TPS just as Paul Suggested. I am among those who have learned that this little piece of equipment can cause more trouble and mislead more people into replacing expensive ECM etc and the little stinky most of the time won't even code. I used a straight pin pushed through the blue and gray wire then put a voltmeter on them with the key on you should have .04 to.05 volts at closed throttle and as you advance the throttle the volts should ramp up to about 10 times what they were at closed throttle or 4.0 to 5.0 volts. If you get 5 volts at closed throttle switch the pins until you get the .04 reading. Hope this is clear.:boogie


th_CorvetteTPS016.jpg
th_CorvetteTPS018.jpg
 
Thanks John.

I'll try it all. Hopefully I can get it in the garage soon and play with it.

tcxd40
 
tc, you never mentioned if the cruise engages. I am just curious, I don't mean to bug you. I have learned from working jets and my motto was to do as much troubleshooting without tools as you can.

Merry Christmas.

Paul
 
Hey there tcxd40....I just went through the EXACT same thing with my '93 6spd 1 owner 40,000 mile coupe, after nearly $1000.00 in tried and failed experiments from a Chevy dealership, it was finally discovered that my Opti-spark was rusted so bad it wouldn't fire the sensor inside. I have never had a water pump issue. The car would fire up and run for a while until it got up to operating temp and then the fire would go out and it would not run until it cooled and then again for only a few minutes. Get some one with a good Sun scope to run a diagnostic on your Opti-spark. The dealership was convinced it was the ECM, and I bought one...it wasn't , but if you need an ECM I have a brand new one. Good luck, but seriously get the Opti diagnosed..:thumb
 
I have looked through the factory manuals I have. Each of the probelms I have encountered all point to one of two parts the TPS and the optispark as far as major items.
Spark plug wires plugs and fuel filter are others. I can't believe that the later are the cause nor the optispark. Ran great then just quit. However it does do what vettebigguy's did, which turned out to be the optispark.
Saturday this week I will be pulling it into my buddy's shop as mine is full. I'll start with the TPS as it is the least expensive then take a hard look at the optispark wiring and the unit itself.
I'll keep y'all informed as I go.

Have not been able to work with the cruise yet as it does not run over 20MPH.

tcxd40
 
Question, could the optispark unit die that quickly? It ran great all the way home, about a 1 hour drive.;shrugtcxd40

My Opti went in an instant; from no percievable problem to dead. After towing it home it would start cold but quit abruptly at 140 degrees. I found that the check valve in the vacuum line was dead (no circulation thru opti) I assume this caused moisture and crap to build up in the Opti so, I now check the line several times a year to make sure it is pulling. Yours may have been prior to the vac line mod. 2 suggestions: A simple scanner is essential - and - keep it away from a dealership. Find a good Vette shop!
 
So Bay Vetter is 110% right!!!! KEEP IT AWAY from the Chevy dealerships , they don't know ANYTHING when it comes to Corvettes...don't make the mistake I did, thinking ,as it was their car that they would know anything about them , THEY DON'T. For all the good they did ( 6 weeks later ) I may as well have taken it to a LADA dealership !!After my fiasco the guy at the dealership told me they get at least 3 a week they can't fix !!! That is a lousy record if you ask me ! Anyway, back to the issue, when you get the scan, check the module inside the Opti-spark that is the part that ultimately failed in my car. If it is an OEM part it cannot be replaced like an aftermarket Opti can, so you will have to replace the whole thing ..like I did as mine was origonal. Keep me posted on your quest..
 
Here is a little ore info on how my guy found the problem....his Sun scope was able to make a print out of what the electrical was doing when the car was cold, it looks like and EKG from your doctor on the paper. Then he let the car sit idling until it came to temp, when it started to act up the second print out was looking like it was having a 'Heart Attack' and then ultimately dies...the term my guy used was ' passed away '...he told me that when the little module inside the distributor fails the engine cannot figue out which cylinder to fire and it just goes nuts trying to get it right and can't and there fore shuts down. Once I saw the print out it was absolutly clear, and with the replacement Opti, she runs hard and strong. Prior to this major failure I did notice that occasionally I would get a little bump in the performance, like it may have had a little water in the fuel. but that was NOT the case. Hope this info will put you on the right track.
 
re-reading So Bay Vetter's post, when my car died the first time it was instant just like his.......at 65 mph on a curvy 2 lane road....that was a wake up call. like his , mine was instant with no previous problems...
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Advertise with the Corvette Action Center!

Double Your Chances!

Our Partners

Back
Top Bottom