Alright. This car is starting to annoy me LOL

I changed out the optispark about 3 weeks ago with a CMS unit, and everything has been fine....Until Friday evening.

I was driving around town for a bit meeting up with some friends, and noticed that the car was misfiring a little bit in low throttle/low load situations. (like rolling out from a stop light) Also, when cruising at around 65MPH at steady throttle, I could feel it misfiring. The weather was a bit chilly, and it was MISTING with fog...humid too. not sure if that has any relevance..

The SES Light came on while cruising, but went out after probably 2 minutes of driving. (this has happened before, without any change in performance or misfiring. Also when I REALLY got on it, it was very doggy and lacked the power that it should. The next morning, i got up and drove it some (nice sunny day, dry and not too humid) and it didnt seem to be running bad at all. It made decent power, and seemed alright. It may just be my parinoia kicking in, but the exhaust seemed a bit less "throaty", and it wasn't loping as much as normal (GM847Cam). I had been smelling a slight whiff of coolant once in a while since the opti replacement, and I found out why that afternoon. The upper rad hose had a pinhole leak on it, and was leaking down the face of the water pump and just barely getting the opti wet near the drivers side plug wires.

I replaced the hose today, double checked everything, and drove it to work tonight. once, and ONLY once, the car missed (kind of like it cut out for a split second) and then drove fine. The SES lit for about 5 seconds when that happened, and it drove fine afterwords (and the ses light was out again)

Things Ive replaced:

Coil (New MSD Unit)
SP Wires (Routed right... very close in some areas and touching
together, away from the longtubes and anything that rotates LOL)
Spark Plugs
Optispark
Opti Wiring Harness
Cleaned MAF


Now, this IS a vented Opti on this car, and I made my own Vac harness. Its virtually identical to the GM unit though. It IS pulling Vac too. I also sealed the cap to the body of the opti with High Temp RTV. This is probably what saved the opti when I had that hose leak.


My only thoughts are this: THe SES light (other than the cut out today on the way to work) is probably O2 sensor related, the car has thrown an O2 code in the past.... and the wires were spliced Next time they are changed, they will get proper extensions. The ICM tests out good. Is it probable that the coolant leak was causing the misfire issues? It seems fine today, other than the single cut out episode.

I'm going to get codes pulled tommorow, so we will see what it says in the computer. Any thoughts?

 

Dont want to be the first one to say it, but its probably the opti spark or something in it. If youve done all of that other stuff, the only thing that it can lead back to is the opti. Ive heard flakey things about CMS optis latly too.

 

My money is on misfire code(s) from coolant intruding into the SP boots on bank 1. 96 car/ OBDII will tell you which one(s) 95 car you'll have to figure out. But you can start with cleaning everything up, especially the boots and connectors, apply a bit of dielectric grease in the boots (don't forget to 'burp' them so they don't back off).

 

Identical in every way? If you are not restricting vacuum like the stock vacuum harness does, it can suck the opti cap in and cause it to clash on the rotor. Result = busted up opti innards.

 

Yep, different vac lines, same length, restrictor, one way check valve, even the wire loom. I think Gojira might be on to something. Even with the restrictor out.... iis wasn't pulling a lot of vac, even on a throttle snap. I put one in just as insurance.