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After doing my first repair on the new to me 94 (underhood light, needed a fuse) I decided to tackle the next issue. The car starts easy and runs great. Accelerates ok up until around 3800 RPM, at which point it stumbles and bucks. I assumed it was the Optispark and even have a Petris one all set to checkout.
Heres where it gets interesting. I read on another thread that the original GM spark,plug wires were numbered by cylinder. Well what do you know, so are mine. Beautifully routed too. The Optispark is very likely original and the spark plugs may well be too. The car has less than 51k miles.
I now plan to check the wires tonight by starting the car in the garage and spraying a little water on the wires. If they don’t light up like a Christmas tree, I might see if I can get away with just doing the plugs.
I find it pretty interesting that the wires weren’t done. The maintenance was stellar. The oil and transmission oil are new. No other way to describe it. After a 50 mile drive home, the engine oil still looks like it was poured out of the a Mobil 1 bottle. Oddly, it has been converted to R134.
Oh and the CD player doesn’t work though the stereo sounds great. A pretty neat time capsule.
Almost comical. I can’t see any fireworks, but it idles smoothly and then I hear a loud pop and it stumbles. Guessing that the 30 year old wires aren’t cutting it.
Well this is kind of fun. While waiting for the plug wires, I started replacing the spark plugs. I have no reason to believe that these are anything but stock, though I don’t know that to be true. They look pretty good for nearly 51k miles. For the purists, the gap was somewhere between 55 and 60 thou.
The General specs the gap at 50 thou. I’ve seen opinions as low as 40 thou. What says CF?
Also waiting for my service manual. I’ve found torque specs at 11 foot pounds. That isn’t very much. Again, what says CF?
OK, the first four plugs are done (passenger side). The only word I can use is absurd. I won’t say how long it took because it’s embarrassing. Schadenfreude prevents me from providing all the tricks that I needed to get it done, but one important one is to remove the rear wire loom from the block. Only two 3/8 head bolts that are completely impossible to see, but it provides you with enough access for 6 and 8.
One humorous item. For whatever reasons, Amazon only sells the plugs in packs of six. I assumed that they knew I’d break some but little did I know, the actual reason is losing them. I dropped the new plug for cylinder 8 multiple times but on one drop, it disappeared. No idea where it ended up. I’m sure it’ll fall out at some point and someone is going to find a brand new plug with anti-cease on it and wonder wtf?
I just had a similar issue with the stumble albeit at a bit lower rpms, and after replacing wires and plugs it was discovered that the entire Optispark had turned itself into a scale model of the rust belt. My mechanic said that because 60% of the car's miles were put on it in Flagstaff within its first two years of life that winter conditions very likely started the 30 year decline. Check your ignition coil terminals as well - those were rusted, too.
I just had a similar issue with the stumble albeit at a bit lower rpms, and after replacing wires and plugs it was discovered that the entire Optispark had turned itself into a scale model of the rust belt. My mechanic said that because 60% of the car's miles were put on it in Flagstaff within its first two years of life that winter conditions very likely started the 30 year decline. Check your ignition coil terminals as well - those were rusted, too.
Kind of hoping that won’t be the case for me but wouldn’t shock me. Might have to remove the coil to inspect it. Very well hidden.
Keep an eye on where that stumble / miss happens, too. It started at that 3800 range but eventually got to the point that I had to limp the poor thing at barely above idle speeds to the shop. Got a full new distributor and its never run better or smoother, at least since I've had it.
Just to close this thread out, I finished replacing the 4 plugs on the driver’s side yesterday. Not nearly as awful as the two rears on the passenger side, but not trivial either.
The best advice that I found was to remove the middle and rear fender skirts. The middle is easy. Just 5 X 10mm bolts and then pull down from the seal. The rear skirt has a good number of 10mm bolts and two different sizes of torx bolts into the fender parts behind the wheel. There is one bolt cleverly hidden on the bottom of the rear skirt.
Once the skirts are removed, you have a direct shot at each plug using a flexible joint and about two feet of extension bars. Be SUPER careful not to cross thread the plugs.
Runs very smooth and even now. The old plug from cylinder #7 showed the same color as the others but the strap looked very white. I need to keep an eye on that one to make sure that the injector isn’t acting up.
Interesting misfire problem
