Optispark or PCM
Thread Starter
2nd Gear
Joined: Jan 2009
Posts: 2
Likes: 0
Optispark or PCM
I have a 93 that failed emission test. It has brand new cats on it so i bought parts to do a tune up and a new water pump. I installed new plugs, wires and removed opti and replaced the rotor and cap. Put all back togather and installed new water pump. Cranked the car and it did perfect. turned it off and cranked a few more times no problems. Noticed a leak on radiator hose removed hose and replaced clamp during this process some coolant ran down the front of the engine and car never cranked again. I have replaced the coil and ICM still no fire. I removed the opti thinking it may have coolant in it but nothing dry. I have read some post here about the opti and the PCM. Anyway i was about ready to order a new opti off of ebay for around 300.00 but would hate to do that and still have no fire. Any help would be appricated.
Burning Brakes
Joined: Feb 2009
Posts: 785
Likes: 3
From: Richmond Virginia
Two things---if your cap and rotor was purchased as a "kit" most come with a new large O-ring/seal---if you didn't replace it and the old one was cracked/leaking OR missing (this is to seal the cap to the opti dist. housing) you likely did get coolant inside the distributor. 2nd thing--check the "opti harness" connector at the opti it may have gotten coolant in it--this is a short harness solely for the opti approx. 2---2 1/2 feet in length---plugs into the opti and into the main engine harness above the right side valve cover--each end has a weather tight seal on the connector over time and with age they can shrink or split and coolant/water can get to the wire terminals. Frankly IMO it's not a bad practice to replace this harness when doing the work you did, whether you're actually replacing the complete distributor or not. 
Instructor
Joined: Jan 2010
Posts: 174
Likes: 4
From: Austin_Palm Bay_Houston Texas_Florida_Texas
If your Opti took a dump and stopped sending CAM position information to your ECM, then you can access your error codes via flashing "check engine" lamp. There are 2 error codes associated with your Opti, and these should be stored if your Opti is at fault:
16 A low resolution pulse was not detected by ECM within 720 high resolution timing pulses.
36 ECM detected less than 60 high resolution timing pulses between each low resolution pulse for 5 consecutive cycles.
You can retrieve error codes easily by using the paper clip method :
http://www.troublecodes.net/GM/
16 A low resolution pulse was not detected by ECM within 720 high resolution timing pulses.
36 ECM detected less than 60 high resolution timing pulses between each low resolution pulse for 5 consecutive cycles.
You can retrieve error codes easily by using the paper clip method :
http://www.troublecodes.net/GM/
Thread Starter
2nd Gear
Joined: Jan 2009
Posts: 2
Likes: 0
Thanks for all the info guys. I did some test and have decided to order new opti and awaiting its delivery. One thing I found odd when performing some of the recommended tests was, when I tried to retrieve codes from the computer I shorted out pins A and B turned on the switch and nothing happened no check engine lights flashed or any service engine light but my radiator cooling fans came on. I just thought this was a bit odd.
