martyp

So I'm going through the maintenance history paper I have on the '90 and summarizing it in a spreadsheet. One invoice from a dealer includes a "Change-over valve" (PN 99660512301), which I can't find in the 928 diagrams. I appears to be an air injection part for the newer cars, and doesn't seem to have any application on the 928.

Anyone have ideas here? Maybe it's a typo, or it's used in place of an NLA part, or?

Thanks in advance

Mrmerlin

if you google the PN you will see a picture of the Flappy control valve.

In the 928 its mounted on the front of the left cylinder head on the S4 and later engines

martyp

Stan your google must be better than mine - all I see are non-928 applications

So it's OK?

Thanks!
M

Mrmerlin

this looks like a flappy control valve to me

http://www.google.com/url?sa=t&rct=j...z9sZMJOKTwwIDQ


BUT to be safe Check PET and verify that part number for the Flappy valve ,
this may be a newer version and or since the 928 isnt made anymore it may be made for a slightly different application

Bill Ball

It sure does look like the vacuum switch for the flappy actuator. PET only shows applications in 911, Boxster but not 928 and the 928 intake part page diagram shows it but w/o a PN.

martyp

Stan and Bill thanks for the help. Bill you hit my confusion on the head - I couldn't find a 928 reference for the part anywhere. You both think it's a flappy, and therefore it is, I'm satisfied.

Bill Ball

It looks like it, but it is odd that the application is not shown in PET. I looked elsewhere to find a PN for the flappy switch and came up empty handed.

Z

#14 - "vacuum valve"

Bill Ball

Thanks Z. I knew if I said I couldn't find it, someone would post it within an hour.

martyp

Hmmm . . . now I'm concerned again. The part Z posted shows 928/964/993 application but no correlation (replacement for, etc.) to the part I'm asking about. The 928 part is also 4x the 996 part price, per autoatlanta.com.

As an aside, would this part play any role in idle speed? Mine is consistently a tad high (~950 to 1K). If so, maybe I'll take a look at the switch that's installed and replace with the 928 part.

So as a general rule of thumb are the last 5 digits of a PN the discriminator? I understand that the first 3 correspond to the application (e.g. 996, 993, 911, etc.), and that many parts are used for multiple applications (so it's common to have 964 application parts on a 993 for example), and further that some parts are replaced by newer ones with different application digits.

As always, thanks to all who graciously share their knowledge and experience - as has been said many times before, is this a great place or what?

Alan

I have a stock flappy solenoid valve here - that version might be an equivalent to it...but its not the same as the original one on my car (or the spare I have in hand).

The stock part is made by Pierburg (W. Germany) 7.21339.13

Alan

martyp

Thanks Alan for the info. I think I'll remove the switch next week when I'm off work and check the (hopefully labeled) part against the invoice number. If it is not correct per Z's info I'll probably replace it.

My search on flappy and high idle leads me to believe I might have a vacuum leak or maybe my tach is not reporting truth, as opposed to this part contributing to the idle. More fun in store!

Thanks to all.

Bill Ball

Although this is not the right part, it would not contribute to you high idle. If this switch works like the stock part, and it look like it does, it opens a conduit for vacuum to the flappy actuator at about 3500 RPM based on an electrical signal. So, even if the flappy actuator itself is leaking, that would not effect idle.

Anyway, you can check that the switch is keeping the conduit closed at idle. Also, you can pull the line off that goes under the intake to the flappy actuator and test that with a vacuum gun, like a Mitivac, to confirm that the flappy actuator is not leaky and the flappy moves - be careful not to pull the line off the actuator. Note this will not affect idle regardless.

If you have a high idle you need to check a lot of different places for potential vacuum leaks. There are 3 small lines and several large ones that go to the throttle housing. If any of are disconnected, they can contribute to a high idle.

Rob Edwards

Here's a pic of the flappy solenoid valve for 928's, for posterity:

Bill Ball

Hmmm...even though it may have similar function, the plug sure looks different.

Marty can you take a picture of your "switch" installed on the car?