My '96 Z24 with 125k miles is not firing the #1 and 4 plugs and sputters. I swapped, then replaced both coils, had my ICM checked at 3 different Autozones(all ok), change the plugs, boots, MAP sensor, and fuel filter. I brought some spark plug wires to allow me to test the plugs. When I disconnect the plug wires on 1 and 4 the car starts and run with some sputtering. When I reconnect 1 and 4 and disconnect 2 and 3 the car turns but does not start. Also, when I let the car run for a while to see if the spark plugs will get the signal when the car gets warm unburned gas is heated in my converter and it glows red, so I know fuel is available.
Anyone know what could prevent 1 and 4 from firing. Looking in the book there are two signals ckt"A" for1 and 4 and ckt "B" for2 and 3 coming from the PCM.

Please Help........

 

Spark starts at the plug. I would get a multimeter & take the wire off the plug. Then have a pal crank the car & check for voltage at the plug itself. Might flicker, which means plug is good.

Now trace back from there. Hook the wire to the plug & disconnect from the pack. If flicker / voltage then good. If not try a new wire or a good wire from another plug (but put it back before you forget where it goes).

Might be a wire is crossing with another. Are all the wires running where 1 is not crossing over another?

Another thing to think of is a bad pack (yep.. had 2 bad ones in a row before)

Hope this helps
Walter

 

It was the Ignition Coil Housing. Resistance readings were good, continuitiy was good between the coil contact and spark plug boots, yet it prevented the signal from reaching 1 and 4 boots. Thanks for the suggestion waltd140.