Rough Idle When It's Damp

[rjames]

Hello -

 

My 99 Forester runs quite well however, when it is damp the idle is very rough and the car intermitantly gets "the shakes" followed by a slight drop in the the rpm. It shakes for only a second then everything is fine until it happens again. The dampness in the air is what appears to affect it, more dampness means it's going to be bad. On nice hot summer days, this still happens but few and far between.

 

More pertanent info: I have about 140,000 km's (about 87,000 miles for the US folk) on it. About 7-months ago I had a problem with cylinder 3 misfiring. The dealer cleaned carbon of the cylinder heads, replaced an O2 sensor, changed the plugs, added a new wireset, checked filters etc, then charged me a bundle of cash and everything seemed ok after that. The rough idling became noticable in the winter. I also had a new-used transmission installed last October.

 

Any suggestions would be greatly appreciated.

[idosubaru]

problems like this when damp are typically sure signs of ignition related issues. being the wires are new i'd suspect the ignitor. be sure the wires are seated properly as well. they are new Subaru OEM wires right? (from the dealer?)

 

lots of issues for such low mileage. sorry to hear all that.

[Jerry DeMoss]

I would check the coil pack if you can.Or possibly sounds like a bad ground?

[rjames]

problems like this when damp are typically sure signs of ignition related issues. being the wires are new i'd suspect the ignitor. be sure the wires are seated properly as well. they are new Subaru OEM wires right? (from the dealer?)

 

I assume the wires are OEM - they came from the dealer.

 

How would I check the ignitor?