Changed Plugs and wires on my 1991.

Went with ACDelco Plat. Rapidfire and Duralast Wires (Nothing Special.)

Previously it ran pretty well, but had a bit of a rough Idle... But I think I was had weak/losing spark due to bad wires. (Found this when I grabbed the distributor to adjust timing... *ZAP*) I will replace Dist Cap/Rotor next week. Also found that the previous owner had EVERY wire backward... The Dist/Coil end was on the plug and the Plug end was on the dist. So they were a bit loose on the plugs and they also had no Jelly. Could have been grounding all the time.

Only 1 concern... Even though the engine runs 10X better than it did before and starts with no effort anymore. 1X while starting it... the engine just stumbled and sputtered when I started it. I shut it off and started it again, it was fine, never happened again.

Any Ideas? I'm thinking it was a fluke... Possibly since I had started it several times in a row maybe confused the computer?

I'm thinking it was a fluke too. I've had that same thing happen a time or two in the past.

Glad to hear you got it running smooth!

I'm having the exact same issue right now too (runs well enough, but a bit of a rough idle). I actually replaced my plugs last March (2010), but since then I did a lot of messing around with injectors that were running SUPER lean and I drove it like that for a full season. Now that I have a new ECM and a proper tune in it, I'm thinking I might have toasted an electrode or two last year and I need to get those plugs changed again.

Yea, probably a fluke.

Heck, I gave a 2000 Silverado that does it every other day, but only once. I was going to do massive diagnosis but haven't got around to it.

It's been doing it for the last 60,000 mi.

I am trying to figure out how the previous owner got the plug wires backwards? Wires must be different on the LT cars. No way you can mess up the L98 wires. Mmmmmm wait a minute I better go out and check........

Glad you got it smoothed out.

Glad you found a simple solution. Start with the easy fix and work backwards. Sometimes you just get lucky. I love when that happens.

Quote:

Actually, mine is an L98 as well, and the plug wire ends are slightly larger on the Coil/Dist. end of the wire(They are also labled Coil/Dist that end.) So, Since they were backward, the plug end was a bit loose. So I "could have" been losing spark from time to time.

Plugs seemed to be brand new, so the previous owner must have changed them just before I bought the car. They were nothing more than the basic Autolite plugs... No plat., nothing... I didn't check the gap on those... they might have been off a bit which would have contributed to a rougher idle. (Just out of curiosity I'll check tonight)