kksi

Ok here I go for the 4th opti and 3rd in the last 6 years. From what the mechanics are saying this may be normal for the LT1 engine. Engine only has 130k and my first opti lasted 118k This vehicle was a pleasure vehicle but now need to use it full time. Ive priced opti's from $149 remanufactured thru Pep Boys and $555 for oem. Can some one guide me where I can buy and what manufacturer is the best quality for the best price?

Thanks

Injuneer

AC Delco or Delphi.

They are available online. Check the sources mentioned at the end of this thread:

https://www.camaroz28.com/forums/lt1...-spark-879000/

Note that the 93/94 unvented unit is usually more expensive than the 95-97 vented.

Replacing the Opti 3 times in 6 years (12K miles) is far from normal. What brands have you used? There are $70 units available on ebay, or from supposedly reliable suppliers that are nothing more than Chinese-made replicas that are often dead right out of the box, or last weeks or days. Even the OEM's mentioned above need the rotor screws set with loc-tite before installation, or the rotor could fly off.

The unvented units like you have in your 94 are prone to corrosion due to the ozone that forms from the high voltage discharge. Adding a vent, or installing a vented cap, emulating the later vented models can help with that problem.

What is failing on yours? Is it the cap/rotor experiencing rapid erosion of the high voltage contacts? Is there oil or coolant intrusion? Do you get the trouble codes for the optical cam position sensor? Have you checked the short Opti harness for corrosion or pin damage in the connectors, or damaged wire insulation? These things are not unusual when you consider that our cars are 20 years old.

kksi

Heres word for word what the shop wrote on the service ticket.

Found code 36. High resolution ( 1 degree) pulse failure. This code indicates problem with optical pickup in distributor. Installed oscilloscope on distributor output- found intermittent signal drop and poor signal on cranking. Distributor should be replaced to correct problem.

Thanks for your help

Injuneer

Sounds correct, and is typical of the cheap optical modules used in the Chinese rip-offs. What brand is it? And, depending where he picked up the signal for the 'scope, could be the result of a harness problem. Could even result from high voltage wire too close to the harness, inducing interference.

DTC 36 only sets if the high res signal is lost for a fairly substantial number of crankshaft revolution as measured from the low resolution signal. The engine will still run with total loss of high res signal, with a minor increase in spark scatter, which you would not notice. It's the erratic signal that causes problems.

What failed in previous units?

kksi

Im a little more knowledgeable about this situation now than years ago. I can tell you what is happening now.

I start the car cold...starts fine. Run till the engine is fully heated up ( 5-10 min) and the ses light comes on. Engine hesitates a little at high speeds during this change but continues to run fine. If I stop the car, turn off the engine for a minute or so , the ses light goes out and I can drive for hours without the light coming on. Ive been doing this since September 2013!!! If I drive with the ses light on and turn off the car for an extended amount of time... hour or so.. I have a very hard time restarting and sometimes wont start at all. I sometimes have to wait till the engine is cooled down for it to start. Also if I start the engine cold, run at low speeds with stops, I run the risk of the engine stalling and hard again to restart.

The first time I replaced the opti was at 118k ( 2008). I had the car idling in the driveway and it stalled. I couldnt get it started again. Towed and had the opti replaced.

2nd time 124k ( 2010) car stalled at high speeds and wouldnt restart. Called AAA for tow and while waiting tried starting again when they got there. Car started. Drove home and had same problem next day. Drove to shop and had opti replaced.

The shop told me that the person that did the first job did an inferior fix. Screws in the opti were loose or missing. So much for using locktite...right??

3rd time now at 130k.

Injuneer

What's the code when the SES light comes on? Just DTC 36?

kksi

yes as far as I know thats the only code

kksi

This is from parts geek. Pricing seems too good to be true. What do you think??


Delphi Distributor Cap
Sale Price: $185.95
with FREE Shipping
Quantity:
(>35) In Stock
Part Number: 3103-05167549
Notes: Distributor Cap -- Actual OE Part
Condition: New

Shipping Options:
Free Ground Shipping

This Product Fits the Following: Warehouse: B
Vehicle Sub Model Engine
• 1994 Chevrolet Camaro Z28 5.7L V8 VIN: P

GaryDoug

You know that's kind of expensive for just a cap, right?

Injuneer

And replacing only the cap will not fix a problem with the optical cam position sensor module. You need the entire Opti inclding the body, which includes the drive system, bearing, optical module, slotted shutter disc, and harness connector, along with a cap and rotor. You might be able to get away with reusing you current cap and rotor, but if its an inferior brand replace the entire distributor.

kksi

ouch.....I ordered thinking I got the right part(s) for my repair. Guess you live and learn. As I already purchased the cap are the other components available individually for sale? Can you advise where I can purchase them?

This is a little embarrassing. Thanks for all your help.

Injuneer

You might find something on ebay. I know you can get the cap and the rotor, but I haven't seen anyone selling the complete base of the distributor without the cap. Check American-Powerhouse. I've seen them help people with Opti info on another site. There are other parts that are unclear whether they would be included, like the dust cover that separates the front from the back of the Opti.

https://american-powerhouse.com/

Here's some good info on what the vented Opti consists of. Your 93/94 unvented unit would be different on the back side, because of the different drive setup. The 93/94 slotted disc is also tack welded to the metal disc that it sits on, and cannot be remove like the one in the vented unit:

Corvette Action Center - Optispark Dissection and Replacement

93/94 drive, courtesy of shoebox:

http://shbox.com/1/93-94_opti.jpg

kksi

Im trying to find an ac delco or delphi distributor but cannot locate one online. Can you help??

moparman

Check Rock Auto and Amazon.

Injuneer

Did you try American-Powerhouse? I posted the link for you. And suggested ebay.