99 OB: Engine vibration (1800 < rpm < 2700)

H

Harman

Greetings,

I just purchased an very clean 99 Legacy OB (30K miles) two weeks ago
and I've made a couple of troubling observations. First, when it's
cold out there is a non-trival amount of valve train noise when I
start it. I changed the oil to Mobil 1 5W-30 and that really helped
but there is still too much noise. Second, the engine vibrates, in
either N or P, between 1700 < rpm < 2700. This happens when it's
either warm or cold. I put some good gas and BG supercharger fuel
injector cleaner to get rid of any gunk but it hasn't helped.

The service bulletin 11-53-98 ( knock sensor thinks valve train noise
is a knock) seems to apply to me. Here are a couple of questions, for
those who have been down this path:

a) Will the enhanced ECU fix the problem?

b) is the dealer going to install a new ECU free of charge, or am I
going to get taken to the hoop?

c) can I test the knock sensor theory by simply disconnecting the
knock sensor?

Todd
 
Harman said:
Greetings,

I just purchased an very clean 99 Legacy OB (30K miles) two weeks ago
and I've made a couple of troubling observations. First, when it's
cold out there is a non-trival amount of valve train noise when I
start it. I changed the oil to Mobil 1 5W-30 and that really helped
but there is still too much noise. Second, the engine vibrates, in
either N or P, between 1700 < rpm < 2700. This happens when it's
either warm or cold. I put some good gas and BG supercharger fuel
injector cleaner to get rid of any gunk but it hasn't helped.

The simple answer is don't rev it up. My 99 Legacy OB is
a little rough in that range too and I don't worry about
it.

If by valve train noise you mean tapping, it's normal and
nothing will fix it. Mobil 1 10W-30 worked even better for
me and you might want to change to it next time.

Some people here on the group have had piston slap and have
gotten various degrees of help from Subaru. I don't know
how to tell the difference between cold-start tapping and
piston slap, but I'm fine with what I hear in my engine.

The service bulletin 11-53-98 ( knock sensor thinks valve train noise
is a knock) seems to apply to me. Here are a couple of questions, for
those who have been down this path:

Very interesting. I don't know anything about this but
would love to hear more.
 

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