Mornings, and after driving many miles the previous day, my 95 850 (133 K) starts very roughly (sometimes not at all) at 8500 feet where I now live. At 6200 feet, no problem. Twice I have had to tow to Volvo. Their diagnosis: manifold is flooded, plugs fouled. Cleaned all, starts fine for them, but back at 8500 feet, it's like starting on 1 cylinder. Eventually it chugs away till all's fine, and continues running quite well. The car does not burn oil.

Owned the car since new, never had any problems till I moved to high altitude.

Any clues?

Thank you in advance

Do you leave the accelerator pedal alone at cold start? I believe the owners manual for the 850 advises giving 50% throttle at cold start above 6000 feet, then release at start. Give it a try.

Info for a 98 turbo indicates there is a barametric sensor for
altitude. I wonder if it has failed. You may need a dealer
to check it out:

The Atmospheric Pressure Sensor supplies the Engine Control Module (ECM ) with a signal describing air pressure. It provides the engine control module (ECM) with the car's height above sea level.

Atmospheric pressure sensor acts on the control of:



Boost pressure at high altitude
Injection time when starting at high altitude.
At heights above 2,400 meters the following are disabled:



Leak diagnostic
Pulsed Secondary Air Injection System (PAIR ) diagnostic
Mass Air Flow (MAF ) Sensor, faulty signal.
The atmospheric pressure sensor contains a piezoelectric crystal in the shape of a diaphragm. One side of this diaphragm is subject to atmospheric pressure, to other side is acted on by a contained gas. The deformation of the piezo-electric diaphragm, and therefore its resistance is proportional to air pressure.

The voltage across the sensor is a function of air pressure and, therefore, of sensor resistance.

Voltage can vary between 0 Volts and Volts .

The sensor is supplied with a stabilized voltage of 5 Volts from the engine control module (ECM).

If the signal from the atmospheric pressure sensor is faulty or missing the engine control module (ECM) adopts a substitute value.

The atmospheric pressure sensor is located by the right hood catch.

Thanks for the info.

My 850 is not a turbo. Is there a similar sensor on standard 850's?

Is it a Turbo 850 ? If it's not a Turbo I would sell it and get a Turbo anyway. At that altitude you have about 70% of the air density the car was designed to use and non-turbos suffer pretty bad performance. Call some indy shops in the area and ask them how they handle it.


Mike ......... Miami, FL