'98 Malibu - idling problems in wet weather

Could be ignition wire fault. With the engine running on a damp night, pop the hood and cut any illumination so that it's dark and look to see if you observe a light show under the hood. If you do, the ignition wires need to be replaced.

"S.L." wrote: '98 Malibu LS 3.1

Bought at 46K, has 90K. No tuneup since purchase, always ran fine.

But now, in RAINY WEATHER ONLY:

1.) Starts good, runs good for a few minutes, then runs rough. 2.) After full warmup, smoothes out and runs good again.

Any recommendations where to start? Steve L. ____________________________________________________

It is probably high voltage breakdown.

1.) Moisture on ignition parts (Distr cap, plug wires, plug insulators) provides easy path for firing current to go to nearby metal rather than across spark plug gap.

2.) Widened plug gap in old plugs is harder for spark to jump.

3.) Old ignition parts have deteriorated insulating abilities.

4.) Richer mixture (easier to ignite) and higher idle speed when first started permits relatively smooth running.

5.) After mixture becomes leaner and idle speed is lower, roughness intensifies.

6.) Full warmup dries moisture from ignition parts and improves insulating ability and smoothness returns.

I think it's time for that tuneup.

Good luck

Wendy & John. _____________________________________________________

One thing that I must comment on is the mileage. We bitch about how crappy cars are being built nowadays, but I don't know of any points & condensor system that would even be running at this point. I must say that I do love technology with regards to how it has helped us keep our cars longer.

PS this one probably just needs a tune up.

Give the poor thing a COMPLETE tune up. It's a wonder it runs at all.

Replace the air filter.