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Engine vibration at idle started this week shaking my 93 Legacy 5spd
130Kmiles. Has been a good performer since 24Kmiles, 1994 (except for
CV axle joint 100kmi, knock sensor 60kmi). The car has yet to stall
so its not too bad. The car was accelerating well the next two days.

I would have expected the CHECK ENGINE light to come on if it was a
sensor problem. It did with the knock sensor years ago.

The third day more vibrations at idle and some at idle with AC on,
plus engine knocking accelerating on a flat road and much worse
climbing a hill. Now its getting serious. Must park it in garage to
investigate at this point.


Testing showed:
The knock sensor CHECK ENGINE CODE: 2-2, and Starter switch (abnormal
signal emitted from ignition switch, per Trouble Code of shop manual)
ENGINE CODE: 1-2.

Code: 2-2
My Knock sensor is getting 2.0V (when connected), 2.4V
(disconnected).

If anyone could please reply indicating what voltage is at the knock
sensor connector on/off?

The Shop Manual says: 3 to 4V disconnected. The resistance of my
knock sensor is about 600Kohm (poor resolution on analog meter) the
Manual says >560Kohm

Code: 1-2

I do not know what to do about this CHECK ENGINE code. Wherev is the
source for this test point. Please reply as well.

Other problems:
The throttle body input air hose was incorrectly attached. The bottom
end was folded inside itself. This was very noticeable when removing
the air hose. The plastic end wanted to return to this abnormal
condition. Engine idle improved significantly after this correction
was made. No doubt the air/fuel mixture was improperly affected by
this travesty. Some carbon deposits in throttle body removed with
carburetor cleaner.

Couldn't say why idle problem started early this week the only two
occasions to remove the air hose was two months ago during an
inspection at the local Subaru dealer and when I replaced the air
filter for a K&N at about the same time, can't see the need to remove
the intake air, maybe loosen it to rotate the air cleaner assembly.

Test Drive:
The car is drivable. If I avoid hills there will be less engine
pinging. The car climbs OK. Pinging on fast accelerations. Idle still
a little rough, not as bad as what it was on the previous excursion.
Did not look at the air valve. I have to get on with my life.

I wonder if I should test for compression and look for a bad valve,
or test the idle air valve, timing belt replacement is overdue the
120kmi service, all of the above or JUST BLAME the ROUGH IDLE on the
KNOCK SENSOR.

Robert Illan
93 Legacy L 5spd 130kmi

It could be the knock sensor. I would check the knock sensor, the o2 sensor,
and the purge valve solenoid. They are all suspect in this situation (the
purge lesser so). If you verify all of those are good - I would look toward
a faulty injector. I'm over 180k miles and I've replaced 2 injectors in the
last 20k miles. I think I've got a third heading on its way out now... Same
problem: rough idle. That same symptom led me to replace the other two. A
leak down is advisable as well - most shops will do it for free as part of
another service or a tune up.

Good luck,

-Sambo

I'd reset the ECU, and then check codes again after driving again.

Knock sensor is fairly cheap 30-40 bucks.......it's been updated from
the original ones.

You can check out my site www.surrealmirage.com/subaru for more info on
the codes and such it's in the notes & tips section, engine related.

Josh