Westphalia Loss of Power; during warmup

engines

#1

I recently replaced the Air Mass Sensor on my 1987 VW Westphalia and am experiencing a loss of power. This occurs while the vehicle is warming up and suddenly loses power, though the engine will still run and rev up if you push in the clutch. My mechanic made some adjustments to the new Sensor but the problem still persists. It appears to be temperature dependent because once the vehicle warms up a bit more it suddenly ceases and then runs well. When the engine is started you can drive the vehicle and it will run fine until this temperature range is reached and the power loss occurs. It reminds me of a problem with an automatic choke on a carbureted engine. This is why I think it may be a sensor. The vehicle does not stall but if it is sitting and idling it will be erratic and acts like it is on the verge of stalling.



The original Air Mass Sensor was failing because it had the usual “los of power” intermittently while driving and this problem is corrected.



Any suggestions on what may be causing this:


#2

You need to understand how the systems, and sensors, work before you can understand when one’s not working properly. Haynes Automotive Emissions Control Systems is one source of such knowledge. The Haynes, or Chilton’s, Repair Manual for your car is another source of systems, sensors, and actuator knowledge. TEST the sensors and actuators; rather than haphazardly replacing them. The test procedures are in the repair manual.

Replacement-by-symptom is a common, but expensive and ineffective way of attempted repair by too many would-be “mechanics”. Test first.