94 surging/missing problem

[copper_94]

short story: bingo.

long story: i took it into the dealer after my mechanic didn't find the problem. he didn't want to start just throwing parts at it, and didn't have any onhand to do any testing with.

the dealer at first diagnosed the missing problem as a couple of bad spark plug wires, and possibly bad plugs. replaced all wires/plugs.

the surging problem he claimed was a MAS with baked on oil from the k&n air filter. solvent cleaned the MAS.

turned it back to me, and within 1/2 mile was doing the same thing. went back, took the service guy for a test drive and nearly put him through the windscreen it was missing so bad.

they kept it for a day and said they couldn't reproduce the problem. went back and took the manager for a test drive, and bucked him around some.

i don't know what they did to diagnose, but called and said the optispark was bad. took a couple of days to get one. took out the water pump and found that it was on it's way to selfdestruction, missing some bearings and a rusty optispark. replaced both. wonder where the bearings will turn up in the future?

runs like a champ now, as far as i can tell with 20 or so miles on it. lots lighter in the wallet, and i can't recommend midway chevy in phoenix for any service at all.

thanks for the help,
charlie

i finally found the problem with the erratic idle.

there is a recirculating plastic tube that comes into the throttle body just aft of the iac. that tube has a short rubber hose connector (that has different inside diameters on each end). that short hose had dried out, cracked, and leaked air. this fooled the computer into thinking that there was more air, so it added fuel. as it heated up, the idle changed amounts because the crack widened or shrunk according to the underhood temps.

regards,
charlie
cave creek, az