I have a 93 Z28 automatic. Last owner put a new water pump and opti on. I stopped to get gas cause I was almost on empty yesterday morning, filled up and when I pulled out of the gas station my car just completely died for a second then picked back up. The SES light came on. I was a mile from work so i drove on. After work the car started fine so i went to the bank. While sitting in the drive thru the idle started going crazy like it was about to die and it was having to add gas to keep it running. I left there to go home, only a few miles away, and it ran fine going down the road....until i stopped. Started idling funny again. I got home and was backing in the driveway and it died on me. Cranked right back, so i sat there about 30 seconds and it died again. Repeated this one more time. It has been idling low for about a week before this. I checked the code....got 36. Read where it detected less than 60 high res pulses between low res pulse. Im trying to figure out why all this is happening and not really sure where to start. Thanks for any help

 

how long ago was the opti changed and what brand name is the opti? everything in the book points to the opti or the ecm.

 

Hey man, I'm not sure how old it is. I'm gonna try to find their number and find out. I just went out and reset the codes and it BARELY cranked. I had to give it gas to keep it running and it was rough so I just turned it off. This stinks! I've only had this car a few weeks.

 

what about plugs and wires. do u know when they were last changed. when i first got the z i have now it would not run after i got it home. changed the spark plugs, they looked really old, and it ran like a champ. did nt have the 36 code though so still points to a ignition problem.

 

I haven't checked those yet. I guess i will tomorrow, not looking forward to it though. The guy i got it from is gonna send me the receipt for the opti and said its only 2 or 3 months old and it came from Jegs. I dont think it had been too long since he changed plugs but im gonna check them all anyway. I'd like to kick whoever's butt it was that thought the opti was a good idea.....and why would you put the main electrical component under the water pump!?

 

im with u mpita

 

I think a service tech designed the optispark so they could make big money when there's a problem with it.
Code 36 means a faulty high resolution signal. The optispark gives a low resolution signal from an inner track that has eight different width slots (one for each cylinder). It also has an outer track with 360 slots to give a high resolution signal. There is an optical reader pickup (where opti gets it's name) to read both of those positions, then sends a signal to the ECM which uses that info to determine the engine's crank position. The ECM will then know when to send power to the coil to fire the spark plugs. A lot of times, the problem with the opti comes from the optical pickup getting gunked up, giving a false reading to the ECM. Your problem is most likely with the optispark unit itself, or with the harness. Check the harness first since it's the easy one.

 

Thanks, I'm going to go work on it now and see what i can find out. I'm hoping something's just loose or maybe just dirty where i can clean it. I'll let you know when i find something out

 

Let me see what you guys think. I noticed there was oil leaking from somewhere. I took the water pump off and saw there's part of a seal sticking out where the gear for the w.p. comes through the timing chain cover. I started the car briefly and there's was a tiny amount of oil came out. Now i figure you multiply that by all the time its been driven and i think thats my problem. The opti has oil all over it. Also noticed its a vented opti so im gonna try to clean it up real good and seal those vent holes. Now i gotta go get the right tool to take it apart. I'm hoping its got some oil inside and has things gummed up. So, what ya think?

 

No no no, don't plug the vents. The opti needs to vent.
Updating it with the newer style (1994.5 and up) venting setup would be a very good idea since you have things this far apart: http://www.corvettefever.com/howto/16758/index.html