Have just bought a 94 z28 for 300 bucks that does not have spark. The owner before me had put in a new opti, but no spark. So far this is what I have gathered:

Injectors are firing, does this mean the opti is functioning correctly?

Have tested the 4 leads to the ICM=
terminal A= 11.85 volts dc
terminal B= 1.3 volts ac (while cranking)
terminal C= ground
terminal D= 11.85 volts dc


Opti harness=

terminal A= 5 volts dc (to low resolution)
terminal B= 5 volts dc (to high resolution)
terminal C= 12 volts dc power
terminal D= continuity to ground


I just put in a new ICM because it tested bad at parts store, however still no spark.

Testing wth spark tester.
Will out of order plug wires cause this effect?


Any ideas would be greatly appreciated! New to Camaro's....

 

Even if the plug wires are crossed, they will still get spark.
Are you getting spark from the coil itself?

 

I'm somewhat in the same situation, well sort of. My 94Z was working just fine the other day. I warmed it up and just started to pull out and the car shut down. Turned it over and over...nothing. Pushed it in the garage and checked all of the tests for the bad opti.

I dont have spark at the plug wires.

I dont have spark at the coil either. Does this mean the coil is bad? or is the opti bad?

slow lx, maybe we have bad coils????

 

Could be bad coil....bad ignition control module.........bad pcm......depending on your year, bad crank sensor.

 

He already bought a new ICM. The CKP sensor does not prevent the engine from starting. It's just there for misfire detection.

 

Just checked, has spark off coil to opti. I am taking that this means the opti is bad huh. Any other way to tell?

I know the injectors are firing...

Guess that does not mean the optispark is good than.

 

Have you done a computer scan to see what codes might be stored there? If not, it's a good place to start.

Spark from the coil and the injectors firing indicates that the PCM is getting a signal from the opti. The lack of spark at the plugs could be a broken rotor, which is known to happen on these cars. It could also be a set of completely bad wires. Pull all the wires and check for spark. Spark at one is possible with a bad rotor...if it happens to be pointing to a terminal.

Good luck!

 

Its a 94 he dont have a crank sensor,as stated could be bad wires,or yes the opti itself is bad..do you know where the opti was puchased?maybe there is a warranty on it still.

 

The tip of the rotor broke off on my car about a month after I bought it back in Dec of '02. Costed me around $380 to fix. But I replaced the water pump while it was all out since the original was leaking a bit out of the weep hole.

 

looks like I am going to take it all apart to check the cap and rotor. I cannot see how it could be anything else since the spark is coming from the coil and going in the unit, but not coming out. I just put all new plugs in it, and the wires were done when the previous owner did the opti so they look good. Water pump too.

 

Rotor fell off or the contact broke off.

 

Ignition module mounted on a heat sink on the front of the head, maybe. Take it off and have Azone test it, free.

 

Spark at coil, none at spark plug wires....clearly not the iCM. If no spark, maybe.

Bad spark distribution = rotor or rotor drive failure....

 

Well I removed the opti, took it apart and did not see any reason why it would not fire.

There was continuity from the coil inlet to the center post and the rotor was totally intact. It had continuity from center to tip.

Also had continuity from the cylinder outlets to the posts inside the cap.

I really cannot see how the rotor and cap are bad, only thing I can see since there was spark from the coil to the opti.....

 

If you have spark into the opti, have an intact rotor and cap then you should have spark distribution. The only thing that can be at fault now are the wires.....