Adamred1908SC

Can someone please tell me what the name of the valve is that holds the RPMs up for 2 or 3 seconds after push in the clutch? How does one go about adjusting it?

My RPMs dive when I push in the clutch and was told that this valve needs adjusting? Is it a DIY job?

Thanks.
Adam

Alan Herod

Who told you about this valve? It's a mystery to me, and I have never adjusted mine; but, I never knew I had one. The clutch cable goes from the pedal and there is no sensor anywhere near it, and the cable connects on the bottom of the bell housing. Automatics have some kind of throttle interface.

Charlie Stylianos

Adam,

I would check the following:

- How does the car idle after warm up? If its around 900-1000 RPM thats about right. If it any less than 900, I would adjust the idle set screw behind the air filter cover to get it to spec. before going any further.

- I've read that if the pedal cluster has had work done to it, it's common to get the clutch and throttle cables wrapped around each other. So when you press the clutch in it could raise or lower the engine RPM depending on how the cables are situated. I'd check that these cables are not interferring with eachother.

- If the previous two items seem OK, I would start checking various engine systems and make sure they are up to snuff. Warm Up Regulator, Decell valve, O2 sensor and mixture settings, etc.

BTW: There is no valve that will adjust engine speed when the clutch is depressed. Your frined may have been referring to hte Decell valve that is supposed to suppress backfiring on decelleration by blocking ports/airways, etc.

Hope this helps.

-Charlie
82 SC Targa

emcon5

There is no throttle cable, it is metal linkage, and the clutch cable has a channel it rides in. Not saying it isn't possible, but if someone got them tangled, they really worked at it

The RPM's should drop when you push in the clutch. The CIS system has a decelleration valve that slows how fast the RPM's drops, but it shouldn't "hold the RPMs up for 2 or 3 seconds"

I don't remember any threads on adjusting it here, but it has come up on <a href="http://forums.pelicanparts.com/forumdisplay.php?forumid=8" target="_blank">The Pelican 911 board</a> a few times. Do a search of the archives, you should find adjustment instructions. A lot of folks think a non-functioning decelleration valve is a good thing.

Tom

Speedraser

No such valve as far as I know. My revs drop immediately when I depress the clutch - I think this is correct. Several excellent Porsche service people have driven my car -- I'm sure they would've mentioned this if it were a problem. BTW, I dislike engine management systems (which an SC doesn't have, of course) that hold the revs up when the throttle is released -- it makes it harder to upshift quickly and smoothly because you have to sit and wait for the revs to fall in order to match revs.

Adamred1908SC

My wrench pointed it out to me when I had it in for a quick look the other day. He pulled on the throttle cable and released and turned to me and said it should be holding the RPMs up longer, and pointed to a silver bell shaped unit near the top of the engine compartment on the left side sort of deep into the comparment, this must be the decel valve? He said it needs adjustment next time I'm in for a real service.

To me its kindof annoying that the RPMs drop so fast I always feel like I'm chasing the engine, hard to describe I guess. I'm a good boy about shifting with a tranny of this vintage, nice deliberate shifts, no speed shifting, with a brief pause between disengaging the gear and selecting the next (not like a slug but not like a drag racer either) so I feel like all my power's gone before I'm in the next gear, especially of course up shifting. I'm not a DE guy yet, the car needs a bit of work (see previous posts) before I start that phase of its life...

Adam

emcon5

I just give the throttle a blip while between gears.

Tom