HELP!! 1993 Subaru Legacy AWD Stalls / Sometimes dies when traveling uphill at 40MPH or higher.?

Question

This intermittent problem is driving me nuts! I have taken this car to multiple mechanics. Each time, the problem seems fixed but then returns. Here are the repair facts... over the last 3 years (approximately 20,000 miles) I have replaced the following hoping to resolve this issue:

1. Solenoid
2. Fuel Filters (twice)
3. Fuel Pump
4. Spark Plugs and Wires
5. Alternator

The problem seems to be worse in the Winter & worse in cold, damp weather. Clears in Summer. The most common scenario is I will be traveling on the highway at speeds of 40 - 60 MPH on a straight, steep grade. Things go fine for a few seconds, then suddenly the car will shudder, the RPMs will drop, the car will start sputtering, shaking, lose power, lose speed, and sometimes die. Often times this is accompanied by a foul, odd odor from the exhaust system. If I pull over, and the engine dies (or I turn it off) I wait a few minutes and then can usually start the car and go again.

This returns each Winter. Help!

Answer 1

clogged catalytic converter

Answer 2

Is your check engine lite on ?? If so we need the codes to help diagnose the problem. If not have the codes scanned as some problems don't turn on the lite.All the parts you replaced should have been checked before replaclng them on a guess and replace basis.I don't see any thing on the list that could cause your problem. NEVER replace ANY part till you know the problem I have a hunch you have water in your fuel. No guarantees but lets pretend. You say this is mainly a winter problem so I would guess it does it now and then in the summer also. In the witer, as you go uphill, especially if you have 1/2 a tank or less of fuel, the fuel would run to the back of the tank, ok ?? Gas tends to float on top of water so if you had water it would want to run uphill and stay beneath the gas. Can you picture that ?? The water would be exposed to the fuel pump pick up tube. If it gets in the fuel system it will go to the injector or injectors depending on your system. When the water / fuel mix reaches the injector tip it is forced, at realitive high pressure, through the injector nozzle and sprayed into the engine as almost a vapor.. When a liquid at pressure is released suddenly to a lower pressure it will freeze. I believe this is what is causing your stall problem. Get some gas tank water remover from auto supply and read directions as to quantity you need. I believe this will solve your problem. Don't know if you understand my diagnosis but try it. I would buy my gas somewhere else also. This moisture usually comes from the stations tanks. If this solves your problem use some every winter. Don't forget to use injector cleaner also aboit every 3 tanks of gas. Get the cheap stuff at wal mart.. works as well as the pricy stuff.

Answer 3

If the engine MIL light does not come on when this happens, then its almost a certainty that it will be an internal ECU fault. Check with your Subara agent for any update flashes that may be around for this problem. It may just be a software problem that happens as the car experiences a change in load as it goes up a hill and alters settings in its brain to suit.

Answer 4

Sounds like an air metering issue. Air flow meter probably. Nobody knows subarus like subaru mechanics. They are funky cars.

Answer 5

sounds like the throttle position indicator

Answer 6

I answered this in detail if you go back to your original post

Answer 7

o2 sensor or catalytic converter is stopped up.