1. Tried seafoam, no difference(through PCV)

2. fuel injection cleaner in the tank, no difference

3. wipe throtle body and spray throttle body cleaner VERY heavily in the throttle body, pretty much eliminated rough idle SO this seems to be the best way to fix rough idle.

4. sprayed maf sensor with cleaner, not VERY noticeable but fuel economy seems better ill see next fill up.

 

 

Now im experimenting with the voltage im getting at idle. when i turn on my lights while im in Park, the rpms drop ever so slightly and the engine rumbles a bit, turn off lights, engine is smooth and idle came up a tiny bit. So now im going to look into new ground cables as the alternator is pushing 14.4v. AFAIK

 

I also have a cracked knock sensor no CEL though, so after i get the new sensor this week ill report on whether it makes it more smoother then it is.

 

Just thought id share. tested on my 93 legacy NON turbo Wagon L. with 190k(about 292,000KM)

Define rough idle. I'd like to know what you define as rough because the rest of us might call it normal.

Have you checked all the hoses? Could be a vaccuum leak...

 

Brian

i consider rough when i can feel idle at all :-p But after i cleaned the throttle body its pretty much can't feel idle at all. Not shaking like its going to die.

replaced the knock sensor, so far the car is amazing now. And idle is very consistant.

I have a '90 Legacy...did you have any surging in RPM? Mine does when it's started when warm - not a cold start. Goes up and down from 1200 RPM to 500-ish for about 10-15 seconds.

 

Otherwise car idles no worse than any other Sube I've had....like Manarius said, I consider it the Subie rumble.

ya, its really weird the way these cars rumble, every other car i have been in has never vibrated like these cars. When i feel like it im going to change my tranny mount, in hopes that it makes it idle even better. Now im hoping to get MUCH better fuel economy with the new knock sensor.

I have this same problem on my 91 Legacy SS

 

Can explain how you get the trottle body cleaner in the throttle body....sorry I haven't done any throttle body work at all so I'm pretty clueless (pics would be appreciated).

 

THANKS ALOT - Justin

Ill take pics of what you need to remove later. Kind of busy.

Just remove the black intake hose, so loosen the clamp with the screw very simple. Oh and there are a few hoes attached at the bottom of the intake, so just unplug them they are held on with butterfly clips. I think just 1 needed to be removed, nothing difficult. Then once you get the intake out of the way doesn't need to come out, spray ALOT of throttle body cleaner inside, i sprayed it, then wiped with a paper towel, however a lint free cloth is a better idea, then just push to open throttle and get inbetween the throttle piece, and get around the top, i just sprayed heavily and it broke away whatever was building up. If this doesn't help much, i suggest new plugs and wires.

 

 

so you don't need to take the whole throttle assembly off...you can just pop of the intake tube and work on it from that opening...I assume the cleaner doesn't matter if it gets into engine but what about all the junk that gets cleaned off?

 

Thanks a lot for the help - good pictures too ! Justin

Nope should not matter it just burns it once you start the engine you might need to give it a little bit off gas starting it after throwing all that throttle body cleaner in the engine, when i did it there was alot of gray smoke once it started. I don't think its debris building up, i think its just oil's or grease.

I still think Seafoam through the PCV and gas will work best. Then you can use throttle body cleaner if you want (don't wipe it out, it's probably just ether anyways). I did notice a small bit of overall smoothness increase when I ran Seafoam through the PCV valve last year.

 

My car's 16 years old, I don't expect it to idle extremely smooth. At the same time, I would notice if it was idling abnormally. My car doesn't shake at all when it idles, even though it idles (when warm) sub-500rpm.

Oh ya i ran the seafoam to through the PCV valve, made a difference but not a wow difference.