WUR Testing Question
 

How do I test the WUR with a multi-meter?

I have very mild surging at cold start above 40 degrees OAT. And it settles down in about a minute to a perfect idle. Below 40 degrees OAT the surge is from 2500 RPM down to 0 RPM with the engine shutting down eventually. And it doesn't correct itself until the engine is fully warm, which is a challenge when it's 30 to 40 degrees outside and driving creates wind chill, or intake chill, or at least evacuates the engine compartment's effort to get warm.

I can check for a vacuum leak with some carb cleaner and I'll do that, but wouldn't I notice a vacuum problem even with "warm" idle? Because the motor seems to perform perfectly when warm. 900 to 1000 RPM idle, and good throttle response. Maybe I'm missing something that could be subtly better?

Without an exhaust gas analyzer I hesitate to mess with the mixture.

Which year SC? The meter test is to see if there is still continuity in the heater element. It's normally around 30 ohms when it's in good shape.

dont mess with the mixture.
remove the electrical connector on top of the WUR and measure the resistance across the 2 pins. should be around 30 ohms. also check for 12v to the WUR. check it pin to pin on the connector.

check warm and cold and system pressures.

what year is your car?

Sorry I forgot to add the year. It's a 1980 SC.

I have never tested fuel pressure before. I'd like to get the right set-up to do that. What do I need? Kind of thing I can get a a tool supply store?

Always nice to know the health of the fuel pump. My daughter's Camaro has a long crank interval before firing after sitting for a while - I'm suspecting fuel pressure. Maybe a dirty fuel filter. Chevy buried the fuel pump in the tank, which requires dropping the rear end out in order to drop the tank. Kind of makes you appreciate a well engineered car like the Porsche.

Hi Alan, go here it has pictures on how to check pressures

CIS Primer for the Porsche 911