93z28lt1

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?

defaultexistence

iTrader: (11)

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

whytryz28

iTrader: (28)

Same thing happened to me awhile ago, ended up being the ICM was bad. Do the free stuff first before you throw money at it.

food nd cars

check the opti wiring harness

shbox

See if there is any spark at the coil wire. If there is (and none at the plug wires), it's a cap/rotor problem.

93z28lt1

so everyones best guess is use what shbox says and then go from there?

shbox

Several suggestions made. If you don't start somewhere, you won't find the trouble.

93z28lt1

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.

shbox

See post #5.

93z28lt1

how do i test the coil wire?

whytryz28

iTrader: (28)

You could pull the coil wire and hold it near and see if spark jumps between the coil and wire.

93z28lt1

i decided to say screw it and just bought a cheap 20 dollar coil and it did not work.
So does anyone else have any suggestions before i just break down and buy the opti?

shbox

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.

whytryz28

iTrader: (28)

Make sure youre testing the harness at the opti and not at the ICM, i made that mistake my first time haha.

shbox

The test suggested in post #2 (which I believe he did) IS at the ICM-not the opti.

LT1

iTrader: (1)

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.

93z28lt1

im going to go outside later and try some of the things you guys said. Ill let u know the outcome

Big Al

iTrader: (1)

If this is true you would have found the problem. I always suggest starting at the ICM. You have lots of information available there and it's very easy to get to. Did you have power and ground? Were the pulses from the PCM on terminal "B?" What was on terminal "D?"

Al 95 Z28

93z28lt1

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

93z28lt1

put the new icm and she fired right up...thanks for all your help everyone