1998 manual Subaru Legacy GT stalls at stops and in neutral, and then runs terribly

Hi,

Here's the story. I bought a 98 Legacy with only 40K miles, but with
the "check engine light" on, from a dealer in New Jersey, got on the
turnpike, and it stalled at the first tollbooth. It started fine, but
the engine sounded like a lawnmower, was shaking terribly, and had a
fraction of the power it was supposed to. I brought it back to the
dealer, he started it up, and it was fine. We later figured out that if
the car is doing this, you can turn it off, let it sit 5-10 seconds,
and when you start it up, it's fine.

Sometimes, the car will start running badly, shaking etc, without
stalling first. Always, though, it's when the RPMs have gone from high
to low pretty quickly, like when stopping, or shifting into neutral
between gears. However, it doesn't always happen, so it's difficult to
replicate.

He had me bring it to a mechanic, who replaced injectors and the Idle
Air Control motor. When I picked it up, the CEL was off, I thought
everything was okay. First time I get on a highway, though, and slow
down due to traffic, it stalls, I restart, it sounds terrible and has
no power, and the CEL is back on.

The dealer had me bring it to another mechanic, who took out the EGR
valve and told me to drive it for a week or two. If the car doesn't run
badly, the EGR was the problem. It ran very good after this for several
days, but occasionally stalled. Then, one day it stalled and shook and
had no power. It did this a few times, but not near the frequency it
had been when I first bought it.

Then, I took it on a 100-mile trip, and it started stalling almost at
every stop sign, sometimes running badly afterwards, sometimes not.

As it is now, I'm taking it back to the second mechanic, who will put
in a new EGR and then do the "next thing".

What could possibly be wrong with this otherwise wonderful car?

 

Find a mechanic that knows how to pull
the trouble codes from the computer and
interpret them.

 

Both mechanics have checked, it's the interpreting that's hard.

The first one saw a code for the idle air control motor and replaced
it. That didn't work. The second one supposedly has better diagnostic
equipment, but there's still the problem of reproducing the problem to
see what codes are generated.

 

Idle air control motor? Like the mechanism that opens the air intake?

I'd suspect the O2 sensor might be bad in that case. See if they can test
that or replace if it's cheap enough.

 

Sounds more like an intermittent lose of signal to/from a
sensor/control unit. You might want to take apart all the
connectors at the engine and to the ECM, inspect, clean, tighten and
smear in some dielectric grease. The grease keeps water out of the
connections and just as importantly, acts as a shock absorber to keep
the pins tight. Look closely at all the pins. They should all be
clean and consistantly shiney.

Pete

 

Not a bad suggestion, particularly in an older car with a little
corrosion perhaps. Ground connections are also important.

As a side note, I just had a MAF behave similarly (intermittent) on my
daughter's '95 Nissan.

Is there any corelation with moisture/rain. etc.? Could be a bad coil
pack or plug wires.


Carl

 

No -- it's usually been dry when I've driven it.

I'm going to see if I can get the codes at AutoZone.

 

Here are the codes:

P0400 - EGR Flow Malfunction
The EGR valve is gone so that makes sense.

P1101 - Fuel Air Metering
This is the MAF, I think.

P1507 - Idle Speed Control