1997 Impreza Outback Sport 2.2 stalls "randomly"

[sinclair]

Hello everybody,

I'm the proud but currently sad owner of a 1997 Impreza Outback Sport, 2.2 l engine with about 150k on it and low compression in one cylinder (like me, I guess) and an automatic transmission.

I love Subarus in general, and I really like this model, but lately I've been experiencing extreme weirdness with random skips, losses of power, and stalls.

Every day, while driving to and from work, the car would run fine for about 10-15 miles at 30-40 mph, when I'd notice some hesitation or momentary loss of power. Then, it would stall, but after restarting would run just fine. I took it to my mechanic, who couldn't find anything wrong. One morning it failed opposite a Toyota dealership and wouldn't start at all. I waited a few minutes, and it took me five restarts to get it across the street, but in the time it took them to take my name and credit card number the problem was gone. They would have thought I was crazy, except that they saw me bring the car in. Two hours and three mechanics later they couldn't tell me what was wrong either, and they sent me on my way without charging me.

I then took it back to my local mechanic again, who ran it, tested it, and basically tried to get it to fail. Fuel pressure was good. The engine cranks over just fine, even when it won't start. And there are NO CELs AT ALL.

For a while I was living with the problem by just waiting and restarting after stalls. Then one day, while I was driving my wife home after dropping her car off at the shop, the car failed a half mile away, and I was able to nurse it back to the mechanic's garage while it was idling very rough. At least they don't think I'm crazy now.

My mechanic is very reputable and both he and his son are the kind who won't replace a part unless they're very sure it's the source of the problem. The IAC has been replaced, and I believe the MAF sensor was done today. When the garage owner took it for a long, moderate speed drive he thought he had it licked, but the car stalled backing into a spot in his parking lot! Now he has the same haunted look I do...

This has been going on for literally weeks, and if it weren't the holiday season I'd have heard the riot act from my boss already for absenteeism. So far, I can think of only a few things:

- The time between engine start and failure seems to be temperature dependent, but not coolant temperature dependent.

- When the car was idling roughly, it improved when the MAF sensor was disconnected.

- Although fuel pressure was good, maybe there's some floating crud that's blocking flow intermittently, or perhaps there's a pump bearing that binds when it gets hot. Will pressure dips produce a CEL?

- I'm wondering whether the coil pack could have a small crack in it somewhere, and that when it warms up, a path for arcing opens up, which closes upon cooling. But wouldn't such an event give a CEL?

- I've read along the way that a crank position sensor could be the problem. Is there anything else that I might have missed?

I apologize for the long message, and I'll confess that I'm just not sufficiently knowledgeable about cars to be of much help to others, but it would be a great relief if I could get a lead on solving this problem. This issue has been a monkey on my back throughout the holidays, and I'd like to get rid of it without getting rid of the car, if possible.

Tnx,

.dale.

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[4wdrift]

When was the last time you had your fuel filter, plugs and wires changed??

[import177]

I had this problem when I had my 97 OBS back in the day. Never did figure out what the problem was...

[69subaru360]

With odd problems like this, one of the first things that should be checked are all the ground wires.

[sinclair]

Well, a quick update:

Plugs, wires, filter are all no more than about 15k miles old. Ground connections have all been checked and OK.

Ignition module and crank and cam position sensors have been replaced.

Latest failure scenario:

Temperature is high 20s.
Drove 10 miles from garage home, waited 10 minutes.
Drove to shopping center 2 miles away, 5 minutes of shopping, 30 minutes of yakking with hobby shop owner.
Driving home, after 1 mile occasional sag in power (feels like transmission shifting), then stall while taking slow speed turn.
Car rolling, put in neutral, car cranks fine, but doesn't catch.
Car stopped, put in neutral, car catches, but dies again.
Car "cold weather" restarted, catches, and stays on.
AT OIL TEMP light flashing, then goes out.
Drive home without incident.

That AT light has come on only twice, during the most recent failures. I'm ready to believe anything now, so let your ideas fly!

[Cobb_Crazy]

quote "AT OIL TEMP light flashing, then goes out.
Drive home without incident.

That AT light has come on only twice, during the most recent failures. I'm ready to believe anything now, so let your ideas fly!"


when was the last time your transmission fluid was changed? are there any grinding or pinging noises coming from the area around the transmission when it shifts or does it shift roughly? I only bring this up because I'm wondering if theres a problem in the tranny thats causing the engine to stall just like if you were to stop a car with a MT with it in gear and not push in the clutch....car will stall, I'm wondering if that might be something like whats happening to you. I mean if your mech has been over the whole engine and found nothing it my be time to start reaching for the sky and checking the whole shabang

[sinclair]

Thanks for the replies. Yes, I have been suspecting the transmission. The shifts don't seem as smooth as when I first got the car, but things aren't nearly as rough.

That's the biggest problem: between failures, the car runs very well, so nobody could find a problem at first.

One thing I learned today is that the AT has a control module (TCM, fancy that) which also seems to have a chat with the ECU. It wouldn't surprise me one bit that an unhappy transmission was the culprit here.

Sooner or later I'm going to get very stubborn and build a datalogger for this beast and snoop everything on the ECU connector, and the TCM connector, too, if I can find it!

[69subaru360]

Originally Posted by sinclair

Thanks for the replies. Yes, I have been suspecting the transmission. The shifts don't seem as smooth as when I first got the car, but things aren't nearly as rough.

That's the biggest problem: between failures, the car runs very well, so nobody could find a problem at first.

One thing I learned today is that the AT has a control module (TCM, fancy that) which also seems to have a chat with the ECU. It wouldn't surprise me one bit that an unhappy transmission was the culprit here.

Sooner or later I'm going to get very stubborn and build a datalogger for this beast and snoop everything on the ECU connector, and the TCM connector, too, if I can find it!

You have a code set in the TCM if the light flashes on startup. There is a procedure to read it, but I can't recall right now. I'm sure you could find it with some searching on the net.

[redsport]

I hate to bump this really old thread, but I'm having exactly the same problem. I wish sinclair would have posted the resolution. It looks like he hasn't been back since this last post. Has anyone else ever figured this out?

[redsport]

Just in case anyone else runs across this problem, here's an update:

I could get the problem to repeat, seemingly at random while idling in the driveway. The car threw no codes. Everything else looked good, no wires out of place, no grounds needing cleaning. Stumped, it went into the Suby specialist. They spent 4 days troubleshooting, looking at sensors, driving the car around. First, the only thing that seemed odd is that the car would go rich just before it dies. An indication that the ecu is sensing a problem and driving rich to protect things, but none of the other inputs (MAF, TPS, Temps, ect) were unusual.

Then they decided to read the transmission control unit. It looks like the readings that are coming off the TCU aren't in line with what the ECU is reading, for throttle position, I think. So the thought is that there's an inconsistent reading coming from the TCU as compared to what the ECU is seeing directly off the sensors and the ECU is trying to go into protection mode.

So they are going to replace the TCU and see if this solves the problem. I'll update again when I know more.

[redsport]

Update - TCU replaced, car still dies. Back to the shop...

[redsport]

We changed the MAF sensor even though it wasn't throwing any codes. All seems to be well again.

[bugeyetex]

One more reason to buy a car with 3 pedals...

[tonycondon]

is it still running good after the MAF sensor replacement? Our car (exact same model, but a 5 speed) has started to act the same way.

[redsport]

Originally Posted by tonycondon

is it still running good after the MAF sensor replacement? Our car (exact same model, but a 5 speed) has started to act the same way.

I can't say for sure if this will solve the problem on a car with a manual, but it has definitely fixed the problem on my car.

[redsport]

Originally Posted by tonycondon

is it still running good after the MAF sensor replacement? Our car (exact same model, but a 5 speed) has started to act the same way.

Any update?