I've got no spark

[Injuneer]

Have you had it scanned?

The Opti produces two pulse patterns... high resolution (the egnine will run without it) and low resolution (no spark, shuts down fuel system when the PCM can't find it).

There are diagnostic codes for loss of pulse signals. It is not unusual to lose the signal due to a faulty/corroded connector on the Opti. Take the harness connector off and make sure it is clean. There is also a "test" connection on the bracket on the passenger side of the intake manifold... a gray 4-pin connector. Make sure that connector is not damaged.

Do you have any high voltage wires running in parallel with the Opti harness? What kind of ignition wires do you have? Do you have any mods?

[Jeff_in_Atl]

After having a brand new OPTI and wiring harness corrode in 6 months, I can vouch for the corrosion.

[N20LT4Bird]

Originally posted by Injuneer
Have you had it scanned?

The Opti produces two pulse patterns... high resolution (the egnine will run without it) and low resolution (no spark, shuts down fuel system when the PCM can't find it).

There are diagnostic codes for loss of pulse signals.

OK, gotcha. If there is a code for loss of ignition pulse, then I may have a corroded connector or broken test connector. I assume it will trip the same code if the Opti is bad and not pulsing. If I do not have any codes stored, then.........? Im goin to put the scanner on it tonight after work.

Also, if the PCM shuts down the fuel, I assume it is just killing injector pulse. The pump is indeed still running, however I have not gotten a noid light on it.

I see the wiring for the high res. and low res. signal to the PCM. What is the purpose of 2 signals?

Thanks

P.S. It a 96 WS6 LT4 w/ stock ignition, taylor wires. The rest of my mods are in my profile.

[Injuneer]

Turn the key to on. The fuel pump will start. After 2 seconds it turns off. It turns off because the PCM does not see the low res pulse from the Opti (since the engine isn't running). Turn the key and start the engine, and the fuel pump should run. If it shuts down, its the loss of low res pulse. The PCM cuts both the pump and the injectors on loss of signal.

Yes, loss of signal will set a code, whether it is lost because the optical sensor in the Opti has failed, or a wire is bad, or the harness connector corroded. The PCM only knows it doesn't see the pulse signal, not why.

If the problem is in the cap/rotor section of the Opti, rather than the optical section, you could have a situation where there is no spark, and there is no code. There are no codes for the high voltage section of the Opti.

The low res pulse is a "cam postion" signal. In effect, it tells the PCM which of the 8 cylinders is on the intake stroke, so that the PCM can fire the correct injector. You can not have "sequential" fuel injection without a "cam position" sensor. This info is also adequate to set spark timing. But the PCM also uses the high resolution pulse - 360 pulses per cam revolution - to set the spark timing with extreme accuracy.

When it works, the Opti is the ultimate "mechanical" distributor, because the extemely high precision greatly reduces "spark scatter", reducing emissions. The "world's quickest LT1" used the optical section of an Optispark to feed cam postition info to a MoTeC engine management computer, driving 8 LS1 coils in direct fire mode. Extremely accurate ignition.

[N20LT4Bird]

Thanks man. I appreciate the info.

[N20LT4Bird]

What the !&&$##! I get home and put the scanner on the thing and crank it over - it fires right up. Runs great - this makes it awful hard to track a no spark problem when the car is running. I guess I will wait till it craps out again.

Looking on the scanner, I notice there is no signal from the CPS. Weird. I am going to contact Ed Wright and see if he programmed it out for some reason.

[Joe 1320]

Originally posted by N20LT4Bird
What the !&&$##! I get home and put the scanner on the thing and crank it over - it fires right up. Runs great

That's always the way. Right now I'm gritting my teeth with the wiring on the Fiero. The Fan relay works, then it doesn't. Then it works again, then it appears to have quit for good. Of course it's the HD cooling system relay which is the only one that isn't available in the aftermarket. It's a GM only part. $50 compared to $5.99 Well..... $27 from a discount dealer. Then there's the resistor kit for the low speed portion of the fan and it's an obsolete part.

[N20LT4Bird]

Ehhh ...........toggle switch, some wire and 12 volts. Just kidding. Yea it sucks.