ScaryFast

Car's dead, no spark. Initial thought, as always, is the opti. However, this time I'm not getting spark at the secondary coil wire. However, the coil (MSD part) ohms out ok and there is voltage at the right wires.

Questions:

1) Can the coil still be bad even if it shows the normal resistance across the primary and secondary coils (~5.3 KOhm)?

2) If the optical portion of the optispark is bad will it also prevent the coil from firing? This seems to be unlikely, I've yet to see the optical portion fail.

3) I have a spare ignition module and plugged that in to eliminate the easy fix first and had no spark at the coil - however, I didn't attach it to the head. Does the ignition module need to be grounded to the vehicle to work?

TIA...

jfb

Defective spark modules and coils go from weak to no spark. Spark modules can be tested at auto parts stores. You can check the coil by disconnecting the primary wires, place a .05 Mfd to .1 Mfd capacitor across the two primary wires and pulse 12v on the primary, you should get a nice fat spark out of the secondary. You can use a capacitor out of an old points type distributor.

RetroTA

My car wouldnt run. I replaced everything includung the Opti (which it needed anyway) I was still getting spark. Finnally I changed the coil with an MSD blaster coil ($20 at local speed shop) and it fired right up!
Yes the module should be grounded also attatched for heat-sink purposes

Lichen

But, the module does not have to be grounded to work.

pcolt94

1) Yes, It can be, things are different when it fires at 25KV.
2) Yes, If no low resolution pulse, ECM will not be driven - no drive for ICM or injectors.
3) No, Does not need to be grounded for a quick test. All electrical connections are thru the wires.

You need to find out if you have output from the ECM. That is the square wave pulse that drives the ICM. You need to find out if you have lost drive from the ECM, or the problem is after.

Disconnect the ICM connector. Connect a meter using the AC scale, and connect to white wire pin “B” (ICM connector), and the other lead to engine ground. Go to a low scale, you are looking for between 1 to 4 volts AC. Crank the engine and see what you get. If you get “0”, the problem is back toward the ECM and opti. If there is drive, then look toward the ICM and coil and related items.

Also check the basics, fuse for the coil (10A) and you can measure the 12 volts on pin A (pink/bk) and D (green) of the ICM connector.

ScaryFast

Thanks guys.

I did the whole gambit of checks with the exception of the AC pulse from the ECM. It's on my trouble shooting list but for some reason I never got there.

I took the optispark apart last night and it looked fine, not that it necessarily has to look bad to be bad. It has to be the coil (or the fuse...will check that first), I'm just having trouble believing that due to the fact that the coil is fairly new...maybe three years and 5000 miles.

Now I have the same decision everyone has at this point...if it turns out to only be the coil is it worth spending the money while the car's apart and putting the MSD optispark on it?