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Opti Spark Symptoms, PLEASE POST

69MyWay

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Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Please post a list of the symptoms your cars developed prior to determining you had a bad opti spar unit.

ex,

Hard start, miss fire at speed, poor power, back fire, check engine light (and the code that appeared when you scanned it).

I am trying to diagnose a really freaky LT1 driveability issue where the car runs great, except it will act as if it is suddenly running on six of the eight when you punch it. It will run like junk. Then, out of the blue it will clear up and run great. It can do this withing a 2 minute period of time. The majority of the time, there are no codes present in the system, and nothing out of the ordinary. However, I did notice it slipped into open loop the last time I had the scanner in place well after it was warmed up and running. When it started running poor it had gone open loop, then it went closed loop and started driving better. I suspected the left O2 going lean making the puter think it was needed the open loop circuit.

I will be running my scanner as well for the next day or two.

I have been getting a left bank O2 lean code. However, nothing seems to add up to that regard.


Thanks,


btw, I am running this combo in a 1936 Ford. I put it together for a fellow last year, but the car has been plagued with issues. I think the engine is trying to rebell and free iteself of the Blue Oval nest.
 
Joined
Jun 20, 2002
Messages
2,509
Location
Tallahassee, FL
Corvette
none right now :(
I had a problem very similar to that, as long as the car was cold, it was in open loop, and it was running great. After it warmed up, it would run like S@#!, whith all of the symptoms you described. While it was running, sometimes it would get better, sometimes worse... basically, the computer was bouncing in and out of closed loop... it turned out to be the computer... I put in a new one and the car ran excellent.

Opti spark usually isn't off and on. It is usually call a tow truck, the car is dead.

What kind of computer does this thing have? I would definitely have it checked if it is a pre OBD computer (1993 and prior on vettes)
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Thanks for the input

It is a 1995 style puter reprogrammed with the MAF turned off as well as several other emission related systems (turned off).

I have a spare computer as well. Both are programmed and ready to go. Maybe I will swap out puters and see.


So far, it ran into the office this morning perfect. We will see how it does on the way home.
 
R

RubyDropTop

Guest
Ah yes, the dreaded Opti-Crap unit. One of GMs more refined mechanical nightmares. Funny you should ask about them, I will be ordering a new Opti and waterpump this week as my car is beginning to give me the hint (throws an occasional code) that the Opti is on borrowed time.

I have heard the rare case of the Opti just up and quitting without notice, but most times they give you fair warning that they are unhappy and are calling it quits. Typically, once the car is started the car will buck, spit, backfire and basically act like a car starving for fuel. The optical eye is receiving a rather mixed signal and the car just freaks out. If you suspect the Opti, I would not take it too far from home. As stated before, once they cut out on you you'll be calling a flatbed.

Has the motor been washed with running water? That is a major no-no with an Opti-Spark; they are very sensitive to moisture and water. Runnning a hose over the Opti can render the car immobile.

As far as the actual code # itself (and don't quote me on this) it is either a 32 or a 34 or 36. Sorry I can't recall exactly; I had my car hooked up to a scanner last Friday and the stored code was one of those. Really wish I could remember. I also believe the scanner pointed out either LOW RES or HIGH RES. Those point to the Opti, unfortunately.

Let us know how you make out.
 

compyelc4

Well-known member
Joined
May 1, 2002
Messages
607
Location
Dayton, Ohio
Corvette
'95 LT1 Coupe, Comp Yell; C6 Roadster, Vel Yell
Dear 69myway,

Don't you remember? You gave me advice about possible causes of my 36 and 42 codes a few weeks ago. The thing maxed out my electrical troubleshooting knowledge!!!!!!!! In short, my 95 began to start hard, act like all the plug wires were reversed for days and finally..........kaput! The biggest problem was that sometimes it started and ran just great. Matter of fact, I'd lose the spark and by the time I finished doing all my electrical testing and measurements I had spark again, so I did not know what the heck symptoms I had just troubleshot (well, troubleshooted just didn't sound right).The EXTERNAL pins that are recessed deep down inside the white half of the unit, were corroded. Also the harness that runs from that to the pass. fuel rail side (a test connection point) was corroded at the connection point, as well. I would start with those. The thing is I never REALLY found out if the Optispark was bad internally or just externally. If you have trouble removing the connector from the Opti, give me a shout.

Final observation: I know the earlier Optis had problems taking in water. The newer ones are vented. After looking at the Opti, though, after it was removed, I don't see how it is possible for the thing to take in water internally. External pin connection corrosion I can understand. Just for grins I closed up the intake and exhaust vent openings with silicone and submerged the little devil. I opened it up and found no trace of water intrusion then or previously as GM had suggested before they replace it. Go figure that one out.
 
D

Drewser

Guest
just out of curiosity

When did they quit using that piece of crap? What did they go to after-crap?
--Drew:w
 

BigRed

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Joined
May 23, 2001
Messages
948
Location
Edmonton
Corvette
1985 Bright Red Rocket
Im new to the idea of TPI and LT1 systems in hot rod but If the Optispark is in good shape Id agree that the computer could be the malfuction considering its been modified to run without P.controls and such.

I would agree with you the try the 2nd computer you have. Also is there a way of testing the O spark with a Ohm/Amp meter or something?
 

69MyWay

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Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
compyelc4 said:
Dear 69myway,

Don't you remember? You gave me advice about possible causes of my 36 and 42 codes a few weeks ago.


Yep,

Except, this is a new unit with less than 3,000 miles, and no codes. I just got done running the car on about a 140 mile trip up to Fernandina Beach.

The car runs like a beast, and smooth as glass down the highway. Then, out of the blue it starts cutting in and out like it is starving for fuel. Nothing unusual is popping up on the scanner during this period as far as I can tell. If you slip it in neutral and rev a little it clears up, then goes doen the highway another 10 miles with no problem.

It will also start doing this in traffic, and you will notice when you go to accelerate, it chokes and coughs. Then, it clears back up.

We did notice the right side fuel injectors seemed to be leaning out when it was dropping in power.

I will pull the main connector out of the opti tomorrow night and eyeball it for corrosion. I know it has a long adapter sleeve that goes down deep in the unit, and the harness clips on top.

You may have a strong point on the possible corrosion.

The cold start has been fine, and it has yet to fail on start up at all.
 

96Holly

Well-known member
Joined
Apr 30, 2002
Messages
117
Location
Livonia, Mi, USA
Corvette
96 LT4 Polo Green Coupe
Just replaced mine...

I just mounted my Opti-scrap but havn't had the time to get it started. However, in cleaning up the area I pulled out the contection to the crankcase position sensor and found a little fluid at the contection. I am assume it was the same fluid that drowned out my opti.... This whole thing started with changing the water pump... "While I am there"...

Could the Crankcase Position Sensor be giving you problems?

(I wanted to butt in because I didn't replace my CPS... Ie if I had problems with new opti when I start it...)
 
R

RandyBSmith

Guest
OptiSpark

I am also having some funny things happen. I have a 93. The service engine soon light come on after the car warms up. Normal driving is fine, but when you step on it - the cars pwr seems to plateau through a certain RPM band. If you step on it at WOT and get close to the red line, it sounds like it wants to skip. When down shifting, it wants to backfire. It does not idle rough and other than those things it is fine. It has done this with a performance chip, a hypertech and with just the stock chip.
Due to ignorance at the time, I did hose down the engine one Saturday and the car backfired very loud - I am thinking that I damaged the opti-spark but the it seems that the car would run rough all the time.

WHat do you thinK?
 

compyelc4

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Joined
May 1, 2002
Messages
607
Location
Dayton, Ohio
Corvette
'95 LT1 Coupe, Comp Yell; C6 Roadster, Vel Yell
I think the hose-down hosed the Opti connections. Pull both ends of the harness that inputs to the Opti. Check for water and/or corrosion. I would ohm each terminal too to see if any has larger resistance than the other.
 

69MyWay

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Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Check out this picture. I finally disected the power plug on the upper passenger side from the opti unit. It appears as if a nice film of rusty coolant water has been sitting on top of this connection area. Notice the reddish brown stain on the business end of the plug.

I sprayed some electric contact cleaner down in the opti, and in the plug. Not much you can do to scrape and clean the connectors. I probed the harness end with a ice pick style screw driver with a gentle scracting action to make sure we have good contact. I dabbed a tad of electric contact grease on the plug end.

I will reconnect in a few giving time for all the cleaner to dry out of the opti plug end.

Maybe this has been the problem?
 

96Holly

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Joined
Apr 30, 2002
Messages
117
Location
Livonia, Mi, USA
Corvette
96 LT4 Polo Green Coupe
Looks like water to me...

That looks like the remnants of water to me. When I pulled out my conector it was clean as a whistle.

I would be nervious about that plug. If you have water there then you might have remnants throughout the opti.

Just a thought.
 

69MyWay

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Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
If you are wondering what this is all crammed into, and why I have not already attempted to just pull the opti and take a look, open this pic.

You will see how I crammed this motor into this car, and there is next to no room to work between the radiator and front of the engine, much less the a/c system.
 

69MyWay

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Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Here is a long shot of the whole car.

I get almost as many looks cruising town in this as I do the 69. It is hard to believe a year has already passed since I first put this puppy together.
 

96Holly

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Apr 30, 2002
Messages
117
Location
Livonia, Mi, USA
Corvette
96 LT4 Polo Green Coupe
Oh...

That was quick!!

Sweet ride!!!

I want to do 32 wit da big block, straight pipes and big Micky Thompsons on the rear...

What did you say??
 

69MyWay

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Joined
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Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Re: Oh...

96Holly said:
That was quick!!

Sweet ride!!!

I want to do 32 wit da big block, straight pipes and big Micky Thompsons on the rear...

What did you say??


In fact, if you are REALLY interested, I know where a pair of sweet fiberglass bodied Jag suspension 32 or 33 coupes are that are in need of final paint, wheels, and the electrical to make them run (as well as interior).

The fellow that has them is the one that got me started on this project. Let me be clear, this is a real 36 Ford (not a kit) that I am working on now. It is not my car. I simply assembled it for some extra $$$$, and now have married it every time it breaks down. The owner is not mechanically inclined, and the chevy dealer near where he lives can't seem to think "outside of the box" to correct, assist, deal with any mechanical problems that have developed on it over time.

To date since I assembled it the car has had two major problems. One, Street and Performance mixed up the labels on the left and right O2 sensors and I did not double check the readings after getting it all running. This caused problems as any change in one side of the engine caused the computer to make adjustments to the opposite side of the engine that made it run really bad. Second, the car has had a hideous moisture problem. It keeps getting corrosion and moisture building in the harness. I ended up hard wiring the driver O2 connector (in other words, cut it out and soldered it straight) to keep it from causing contact problems. The owner lives near the ocean on a salt marsh. I think the old 1936 body and frame have a high content of some sort of metal in them that attracts moisture/corrosion to the weakest most pure link (the harness). I have suggested they install zink plates (like a boat) throughout the frame and body to act as a buffer.
 

96Holly

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Joined
Apr 30, 2002
Messages
117
Location
Livonia, Mi, USA
Corvette
96 LT4 Polo Green Coupe
Tempting....

The '32 is in my future but not my close future. I have to get the Vette payed off first (Or sell it for another project car) Funny how a family changes perspectives.

Good idea with the connections. (Ie using zink plates) I am not familiar with them or how they work but if they work good on a boat then it would almost be bullet proof on land. I have used the simple silocone on my conections with the opti. I can't wait to get it all back together.
 

69MyWay

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Joined
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Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
The clean up and treat job on the main opti plug did not fix the problem. It runs about 15 miles, then gets stupid. I have also been corresponding with C4C5Specialist. He seems to think the opti has been compromised.


Soooooooo, I had Nikki pick up a new opti for it today. I just got done busting knuckles and cutting my fingers up on the radiator fin blades and other items. Several hours later I have an opti in my hand.

BTW, the lower balancer hub does just knock right off after pulling the three bolts. It had been a year or so since I last fooled with one and could not remember. G.M. made the lower passenger side opti mount bolt just long enough to interfere with the balancer. We are running a Vetter balancer on this car to make the pulleys line up right.

Back on topic,......hm, what could be causing this problem?

Take a look at this photo and let me know what you think. I predict another trip to the Chevy dealer.

How can this happen with only 3,000 miles on the car? I have been smelling the sweet tell tale smell of coolant around the car when it hits temp, but no puddles on the ground.
 

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