tomfric

I have a 93 z-28 lt-1 6 speed, going down highway car shuts off still have dash lights ect. sometimes will restart sometimes crank away, brand new fuel pump assembly and relay. very confused the problem happens almost exactly same distance from my house about 7 miles at 50mph. thanks for your thoughts. opti spark was changed out recently also

Injuneer

Did you have the same problem BEFORE the Opti change? What brand Opti did you install?

Did you have the same problem BEFORE the fuel pump/relay replacements?

SES light come on? Have you scanned it for codes - there are a couple of fatal codes (Opti cam position sensor and ICM) that do not turn on the SES light.

tomfric

I had the same problem before relay, same problem before pump assembly, not shootng any codes. all I am doing is spending time and money, not sure what opti-spark it was my/sons car and he paid for that part. not sure what the ses light is, how would I detect the opti-cam sensor thank you so much for your help Tom

Injuneer

Check for codes, even if the SES light is not on. As noted, the two that could produce that result do not turn on the light.

You might want to have a shop test the ignition control module. They do suffer from heat soak with the location on the head. When the shop tests it, they have to make sure they get it up toward the normal operating temperature.

The other heat soak issue is the optical cam position sensor module in the Opti, but if that was experiencing intermittent problems, it would still set DTC 16 and/or DTC 36 for loss of the required pulse signal from the module.

tomfric

thank you see what I can do when I get out of work.

tomfric

just played with it iced icm down and starts i think a big wahooo is in order go get part tomorrow and see what happens,thank you so much

Injuneer

Good luck!

tomfric

okay my wits end just came back "on the hook" again any suggestions same exact problem. except made it to work and died on my way home. thanks for thoughts

Injuneer

Missed the basic part of your second post. SES = service engine soon light. When it stays on it indicates that the diagnostic system in the computer (ECM) detected a problem with the engine. All you need to do is short a couple pins in the diagnostic port (connector under dash by your right knee), and the ECM will "flash" the code on the SES light. I'm on a phone right now, but I can post a link to the instructions.

The two codes that will shut down the engine, for the Opti and the ICM, do not turn on the SES. That's why you need to scan it even if the SES light isn't on. The Opti will set DTC 16 and 36. ICM will set DTC 41 or 42.

tomfric

thank you if you can post the link I will do it tomorrow I had another long day of law enforcement thanks again

Injuneer

Courtesy of Shoebox:

How to pull codes on a 93:

http://shbox.com/1/dlc2.jpg

Code definitions:

http://shbox.com/1/Dtcs.htm

Note that 1993 is unique in many ways, including some of the codes. Look at the column on the far right for 93 differences.

tomfric

hey just a quick update, was finally able to put on a friends computer and no codes, seems to be pointing at an opti-spark failure, if any body has a good 1 that can be given some sort of a guarantee. I would like to see what you have thanks