Opti?
Thread Starter
Race Director
Joined: Dec 2005
Posts: 13,515
Likes: 12
From: Fisher, IL
Opti?
I have hear a lot of bad things about this opti thing. exactly what does it do and what does it look like so i make sure i don't do anything to it. I'm no mechanic so im not very knowledgeable about these things. pics would be nice. and no i am not planning on washing my engine bay. just want to know what it looks like so i can curse at it.
Le Mans Master
Joined: May 2005
Posts: 7,362
Likes: 2,281
From: Central Maryland
The Optispark is an ignition distributor. It has a cap & rotor to distribute spark from the ignition coil to the correct spark plug, and a perforated optical triggerwheel that works with two photodetectors. The optical section feeds camshaft position, velocity and acceleration data to the ECM (engine's computer), which then decides exactly when to fire the ignition coil.
It's nearly impossible to see the Opti with everything fully assembled. It's bolted to the front of the engine, behind and below the water pump, and is driven directly via a mechanical coupling to the front of the camshaft.
Does this help?
Be well,
SJW
It's nearly impossible to see the Opti with everything fully assembled. It's bolted to the front of the engine, behind and below the water pump, and is driven directly via a mechanical coupling to the front of the camshaft.
Does this help?
Be well,
SJW
Le Mans Master
Joined: May 2005
Posts: 7,362
Likes: 2,281
From: Central Maryland
For more details, aim your browser here:
http://www.gmhightechperformance.com...htp_optispark/
Be well,
SJW
http://www.gmhightechperformance.com...htp_optispark/
Be well,
SJW
Drifting
Joined: Sep 2003
Posts: 1,483
Likes: 4
From: middle TN
Originally Posted by tparkhi2
I have hear a lot of bad things about this opti thing. exactly what does it do and what does it look like so i make sure i don't do anything to it.
However, a teaspoon of coolant will destroy it.
Last edited by Scooter 94; Apr 28, 2006 at 12:12 PM.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Good info so far and here is some additonal operational details 
The way the whole system works is the reference pulses from the opti tell the ECM/PCM what the crankshaft position is and what cylinder next to fire. Then the ECM/ PCM takes all the sensor inputs from the engine (MAP, TPS, temp etc) and determines spark timing. It then sends a pulse to the ICM. This will advance or retard as needed. Since the pulse is real small at 5 volts it can’t drive the coil. So it’s function in life of the ICM is to amplify this pulse to a level big enough to drive the coil. There is about 40 volts applied at the same frequency to the primary of the coil and hence the secondary produces the 25K volts which goes to the cap of the opti. The rest you know, the rotor is at the correct position and fires to that plug like any other system.
It’s really a neat system and the precision is with in 1 degree error in timing. The reference pulses are 720 per camshaft revolution or 360 per crankshaft. I use to wonder why thy put the darn thing on the front of the engine. But now in my opinion it was for accuracy. There is to much slop in a regular shaft and gears and direct off the cam takes the error out. Charge on
The way the whole system works is the reference pulses from the opti tell the ECM/PCM what the crankshaft position is and what cylinder next to fire. Then the ECM/ PCM takes all the sensor inputs from the engine (MAP, TPS, temp etc) and determines spark timing. It then sends a pulse to the ICM. This will advance or retard as needed. Since the pulse is real small at 5 volts it can’t drive the coil. So it’s function in life of the ICM is to amplify this pulse to a level big enough to drive the coil. There is about 40 volts applied at the same frequency to the primary of the coil and hence the secondary produces the 25K volts which goes to the cap of the opti. The rest you know, the rotor is at the correct position and fires to that plug like any other system.
It’s really a neat system and the precision is with in 1 degree error in timing. The reference pulses are 720 per camshaft revolution or 360 per crankshaft. I use to wonder why thy put the darn thing on the front of the engine. But now in my opinion it was for accuracy. There is to much slop in a regular shaft and gears and direct off the cam takes the error out. Charge on
Burning Brakes
Joined: Nov 2005
Posts: 1,211
Likes: 2
From: Dumas Arkansas
About 3 months ago I thought I lost my opti when the upper radiator hose burst all over the opti. In fact I got stranded and had to get towed in. I got the code 36 and most here said that was the opti death code and to go get a new one. After sitting at the stearlership for about 3 weeks he said my coil wire was bad and not the opti itself. So since replacing the coil wire I haven't had the slightest problem yet. Knock on wood.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
My coil wire went bad to. Right at the opti was arking to the waterpump. It was never wet and caused a no start condition at times or sometimes rough running. Had it running one day and looked down and saw a few arks, right place, right time. Changed the wire ($22) and good to go. You got lucky, the water killed the spark before the opti got wet while it was running. Sitting for a while could have saved the opti cap from arking and carbon tracking. If you ran it right away you might have kiled it but who knows. 
Charge on
Had it running one day and looked down and saw a few arks, right place, right time. Changed the wire ($22) and good to go. You got lucky, the water killed the spark before the opti got wet while it was running. Sitting for a while could have saved the opti cap from arking and carbon tracking. If you ran it right away you might have kiled it but who knows. Charge on
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski