[Poolio]

Hi, I have a 97 z28 automatic. It randomly dies while driving. I have replaced opti, coil (msd) and icm. I looked at shoebox and found this. I have 1-4 volts at cranking so my opti is sending a pulse. I have power going to both the coil and icm. Still no spark from coil. Coil tested at 5.9 ohm's so I believe it's good. The car currently won't start. I have heard of ignition switch problems, would that cause a random no spark? Any help would be appreciated. This is my first post. Love the car it just won't cooperate

 

[PHXLT1]

Ok maybe you have an issue with the ignition. When the car dies do the dash lights go off too? Maybe its a fuel issue? Does the car sputter before it dies? Does it start up right away? Is it hard to start? Sounds like your getting voltage so you may have another issue.

 

[shoebox]

No spark even at the coil wire? Have you checked (ohmed) the coil wire?

 

[Poolio]

There Taylor wires, brand new. I will check it though. The car randomly starts and then while driving will shut off. After it dies I pull the coil wire off and check for spark and I have none. No sputter at all, it is like someone flicked a switch. I hope I don't have to pull the column off to check the ignition

 

[shoebox]

Do you have the 1-4v ac (and other good readings at the ICM) when it won't spark? Have you checked for trouble codes? Not all codes make the check engine light come on. The intermittent nature might mean a poor harness connection.

 

[cocobolo95]

Take your icm to an auto parts store for testing. Make them go through several test cycles as icm is prone to fail when hot.

When putting old icm or new replacement icm back on, make sure you use heat sink compound on it;'s back and on heat sink back, so icm won't burn up quickly.

Might be an idea to test the ignition switch wiring and connectors. We have 96 factory service manual located in 4th gen section. It will have all wiring diagrams. Look for thread titled "GM service manuals"

When your checking the electrical part of ignition switch, located under dash attached to steering column, first check connectors for burnt pins, loose pins, broken pieces.

Then use wiring diagrams to make sure all power inputs to ign sw are good. Then with switch in run position, that all outputs from switch that should be live in run position, are providing battery power.

One last area to check since you have auto trans. Trans electrics get their power from same fuse as coil and icm. If there is a problem, especially an intermittent problem with the trans power wire, connector, solenoids, switches, this can pull down power to your coil and icm causing car to not run or run poorly.

 

[Poolio]

Fixed

It ended up being the coil I thought....after replacing coil the car started. The next day dead again wtf!!! My friend wiggled the wire that plugs in the bottom of the coil and vrrrmmm it started. Cut off the end, went to the junkyard for $5 cut one off another car and works perfect. Theankyou for all your help

 

[shoebox]

Thanks for reporting the resolution. It helps people when they use the search.