peter-997

Hi.
Today I've triggered the idle control valve with my PST tester because I wanted to know how the valve is working.
When I start my cold non-Varioram engine it is non round working (sawing) for a short time.
I've posted this short clip.
Idle control valve.

Does somebody know if the swinging flap is normal?

pp000830

Hi Peter,
Looks normal to me. In regular operation, it continuously moves as a result of pulses from the ECU. The pulses can be felt as vibration as it makes humming/buzzing sounds if it is working correctly.
In test actuation mode it probably receives signal pulses in alternating sequence so the valve is proven to rock back and forth as you see it. Are you having some symptom that prompts you to think the valve is suspect?
The valve has proven to be very durable and generally just needs a cleaning every 30k miles or so and rarely needs to be replaced.
Andy

peter-997

Hi Andy.
thank you for your assessment.

I have ordered a NOS valve from a guy who is living in Czech Republik.
When I got the valve I will compare it with the old one.

pp000830

Hi Peter,
Sounds like a plan;
Be sure to seat the electrical plug into it fully. Sometimes the rubber seal in the base of the plug gets dislodged and impairs its full insertion.
Have a great day,
Andy

peter-997

This is the difference with a new valve.
NOS valve

It is also a little bit swinging but the sound of klick is more powerful and the movement of the flap in the valve is more tight.

The cold idle revs of the car is better than before.

911F1

Quote from a Pelican DIY. Any truth to the cleaning potentially hurting the valve? And when did these valves get so pricey.


https://www.pelicanparts.com/techart...eplacement.htm
"While lots of people will tell you that you can simply clean the heck out of the valve with carb clean and reinstall it; this is not a good long term solution. If you clean the valve and it helps fix the problem then you know that the valve is at fault and it should be replaced. Putting a valve that has been soaked in cleaner back into the vehicle may save you a few dollars upfront but the cleaner will eventually eat through to the coil wraps in the valve and lead to failure, and can on occasion lead to an electrical spike getting back to the DME. If cleaning the valve solves the problem that is a good diagnosis that it needs to be replaced."

Marvin the alien

New Idle control valves are available Ex-Germany for Euro 56.00... Happy to post a link if permitted..

pp000830

Hi 911F1,
I have to respectfully disagree, my 993 with well over 100K miles on the odometer, and the original valve has been cleaned five or six times with spray carb and choke cleaner to remove the carbon deposits and allow the rocker butterfly to flop freely. I do agree the valve should not be emersed in solvent as this will probably cause the solvent to work its way into the electromagnet side of the valve and potentially damage the internal insulation.
It continues to work perfectly. If one has a concern about the insulation of the electromagnet's winding one can always use CRC QD spray electronic cleaner or similar that does not attack delicate wiring.
A new valve purchased in a BOSCH box is a $260 part
https://993servicerepair.blogspot.co...r-robbing.html
Andy