How can you tell when the opti is bad, or if it's just the cap and rotor that need changed? I'm having a rough idle at times, especially when it's wet out. Like first thing in morning after raining all night. Also get a lil miss lately at times too. No codes yet though. Feel and hear the power loss though. Exhaust sounds like crap when it happens. I also am leaking coolant. I am only going to assume that it's from the waterpump. It's been running better for the past few days though. So how do you know if it's the opti itself which costs an arm and leg, or just needs new cap and rotor? Any help would be appreciated.

 

There's really no sure way of knowing if its your cap/rotor or the encoder. You should get under the car and verify if the water pump is leaking. How many miles are on the opti/water pump?

I know it adds up, but I would recommend swapping in an electric wp (assuming the wp is leaking) and a new ac delco opti. The vented opti isn't terribly overpriced, I think its around 250 after the core.

 

If the problem is in the optical sensor, it should set DTC's for problems with the high and/or low resolution pulse patterns. Unfortunately, there are no codes caused directly by problems with the high voltage functions, but if its not firing correctly, is should set off the blinking SES light for random misfires (you don't indicate an OBD-I conversion in your signature, so I'm assuming you still have the misfire detection features of OBD-II).

 

I know it is a lot of work to remove the opti, however, most of that work is removing the water pump (draining the coolant, Etc). And, it appears your pump is going bad, so the pump has to be pulled anyway.

Once you remove and open-up the Opti, in most instances you can see what the problem is. As pointed out above, if the optical module was bad you would get either high or low resolution pulse DTCs.

WD