Lt1 with zero spark
Thread Starter
Staging Lane
Joined: Oct 2008
Posts: 77
Likes: 0
From: Saint Charles, MO
Lt1 with zero spark Alright guys i need some help, My 93 z28 took a crap on me the other day while driving. I was just driving it normal and it died driving down the road.
I checked for spark and there is zero spark coming from the plugs. Im assuming and opti but i dont want to spend the money on one if that is not needed. Any suggestions on how or what to test to see what the problem is?
I checked for spark and there is zero spark coming from the plugs. Im assuming and opti but i dont want to spend the money on one if that is not needed. Any suggestions on how or what to test to see what the problem is? 
NO WAY!!!no spark on a lt1!!??!
start here
http://shbox.com/1/4th_gen_tech2.html#opti_test
fwiw, it might have lost a rotor screw and not need replaced entirely
start here
http://shbox.com/1/4th_gen_tech2.html#opti_test
fwiw, it might have lost a rotor screw and not need replaced entirely
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Thread Starter
Staging Lane
Joined: Oct 2008
Posts: 77
Likes: 0
From: Saint Charles, MO
Alright so i have went through the entire shbox link and everything checked out alright. What should my next step be? Any how to guides along with advice would help tremendously.
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TECH Veteran
Joined: Dec 2008
Posts: 4,147
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From: Little Rock, AR
TECH Veteran
Joined: Dec 2008
Posts: 4,147
Likes: 62
From: Little Rock, AR
Do the coil wire test, first. Pull the coil wire off the opti, position the metal end near a good ground. Crank and watch for spark to jump the gap. If no spark, check the coil wire for continuity. If no spark is coming out of the coil (you said a new one did not change anything), then the trouble could be your ICM or ICM harness connection (since you tested good opti signals and power to the ICM connector already). If you have good spark out of the opti end of the coil wire (and still no spark at any plug wire), it is time to inspect the opti cap and rotor.
TECH Veteran
Joined: Dec 2008
Posts: 4,147
Likes: 62
From: Little Rock, AR
Try check to see if its the ICM, Number 11 on the diagram.
ICM's can go bad because its mounted on the head and the heat coming off it can damage it.
ICM's can go bad because its mounted on the head and the heat coming off it can damage it.
Last edited by LT1; Aug 19, 2011 at 05:05 PM.
Al 95 Z28
Thread Starter
Staging Lane
Joined: Oct 2008
Posts: 77
Likes: 0
From: Saint Charles, MO
next test for a pulsing ground at the dark green wire(96-97) or the White/black wire (93-95) at the coil coming from the ICM. Do you have a pulsing ground?
Yes, next step
No Replace the ICM *note, I have seen a bad coil burn up an ICM. It might be a good time to replace or upgrade your coil*
So i found this didnt have pulsing ground so i am replacing the icm tonight and am going to see what happens
Yes, next step
No Replace the ICM *note, I have seen a bad coil burn up an ICM. It might be a good time to replace or upgrade your coil*
So i found this didnt have pulsing ground so i am replacing the icm tonight and am going to see what happens