97 Legacy Outback runs poorly when wet

[jbmorse]

Car: 97 Legacy Outback, 5 spd, 202k miles

This problem first came up when driving through one of our many winter storms of this season. I was driving along the highway and the car suddenly began to studder and lose power. I pulled off at the next exit and took a peak under the hood for a loose plug wire or anything obvious, but saw nothing.

The temperature gauge read normal too, btw.

So for lack of a better idea I continued and the car snapped out of it. Now it seems whenever I leave on a rainy or snowy morning the car will studder and run really poorly, almost to the point of stalling completely. It seems to happen at lower RPMs but I can usually throw the clutch in and bring the revs up to redline and back. The problem seems to go away after a few miles, or when the car is warmed up (or maybe dried off).

It also seems to be generally lacking in power but I don't know if the two are related. What stumps me is that I replaced the coolant temp sensor last year with an OEM one and put in expensive Bosch plug wires using dielectric grease, so I tend to doubt it's a plug wire problem. It definitely "feels" like an electrical thing though.

I have seen posts here indicating that lack of power is often a bad knock sensor. I don't believe mine's every been replaced but it wouldn't explain the wet condition problem, would it?

And in the interest of full disclosure there is a CEL showing a bad front 02 sensor. Don't know whether that's related or not.

Any ideas would be appreciated!

Thanks

[Olnick]

Listen to what your car is trying to tell you--replace the O2 sensor! If it has never ben changed you're way past due. Check ebay or Amazon, you can get a quality Bosch sensor quite reasonably there (just make sure it's the correct one for your car.)

 

Pull your plugs and inspect them. Replace them with NGKs if needed.

 

Personally I would only use OEM plug wires--"expensive" is no indicator of proper operation.

 

Remove your knock sensor and inspect. If there are any cracks replace it.

 

Do a general "tuneup." New filters, new PCV (and clean or replace the rubber tube leading up to it--they can develop cracks & splits), clean the IACV, maybe a top end Seafoam treatment.

 

These may or may not solve the problem but to me it's a good--and necessary--starting point.

 

Good luck.

[Rooster2]

The problem seems to be electrical in nature. My first thought when reading your post, would be to replace the plug wires, but you just did that recently. I too use the Bosch plug wires with no issues. It is the cheapie wires from the auto parts stores that cause problems.

 

Suggest you pull the codes generated by the CEL. There may be more then just one for the 02 sensor.

 

Since your problem seems to be water related, suggest you wait until dark, raise your hood, and with the motor running, spray water or Windex on your plug wires, and on the spark module. If you see and hear electrical arcing, followed by poor performance, then you prolly have found the source of the problem. Use a flashlight to shine on the arcing area to identify the exact location.

[jbmorse]

Thanks fellas for the good advice. I will definitely change that 02 sensor soon.

You might be right about that PCV tube being cracked. I remember it being pretty tender when I changed the PCV valve a while back.

I will definitely go through and change the wear items that are ready. I will also inspect the knock sensor now that I know what and where it is.

And Rooster I like your idea of starting the car up in the dark to look for sparks. I will give that a shot as well.

Thanks again. I shall report back when I get to all this and let the forum know what I think the problem was.

[bizzy102]

Its going to be hard to figure out this one. i have a problem with my 97 .2.2 when its hot. I get ths stummble around 20 mph all the time!! I was told it was a ecm problem that when the car use engine inputs and burns it into the memory. Basically i was told the ecm is sending out the wrong info to the engine and gives bad performace values!!! So i guess i need a ecm. Might try to replace the coil first and see what happens....

[1-3-2-4]

why does everyone blame the ECM before fully going over everything else?