Hey, could anyone explain the purpose of the Pneumatic Deceleration Valve on a D-jet?
Haynes says its "USA only" so I'm assuming its smog related. (I also notice its missing in any pictures of the engine)
Does anyone have experience running without it?
My plastic "T" piece between the Aux Air Reg and Manifold has long since rotted away and I'm finding it a tough piece to come by.

(the previous owners solution to *any* pneumatic-line problem seemed to be electrical tape )

Can it (or just disconnect it and plug the uneeded lines)

Is this Russ from Atherton ? Young guy ? Dad works at HP ?

B

Brad, does removing the decel valve have any benefit? Why do people remove it?

Yup (or yep, depend'n where yer from) I took mine off and plugged the hole in the intake plennum. This pic shows the little plug where the hose went. Can you find it?
bruce

Chris, its another vaccuum leak waiting to happen.

Bruce.. its right here:

Man.. I havent even seen a complete 1.7 in a car in 8 or 9 months.
B

It could be here also:


LOL



B

Yupper! you got it Brad... You win a Fat Tire the next time I see ya
Geeze! you got eagle eyes. I had the little "Y" in there when I got the car but found it to be very cracked and causing a vacuum leak. I did a much needed re-plumbing job. Other than that, most everything else is still there.
bruce

Bruce,


I see this shit in my sleep. Its a sickness that I cant recover from.

Why is your computer mounted where it is ?? battery tray gone ?


B

Thats how they do it Oregon

All I know is it's a California (EB) 1.7. There are no signs of it ever being on the firewall. It sure is easy to get to when tracing the wires & doing checks and it's easy to remove to allow easy access to the injector, Head temp sensor & spark plug.
bruce

Ummm Bruce,

They didnt mount to the firewall. They mounted to the battery tray. They hung between the tray and the firewall.


B

Chris.
Watch yer mouth sucka
I'll hav'ta come up there & have breakfast wit'cha!!!
bruce

I'll have to take a gander at that area & see if there's any leftovers!
bruce

Now that I think about it I'm kinda glad it is where it is for all the messing around I've had to do with it!

Have breakfast, check out the town, and for lunch walk two shops west from where you had breakfast, and Ill make you the best caesar salad and "gourmet" pizza you've ever had. :cursor:

You worked at a food place while I was up there... and we hung out at Barnes&Noble ???


B

Jeez.. i walk away from my computer for a couple hours (to work on my 914, of course) and look what i miss out on.
Thanks...that sucker is history. I didnt buy a '73 because i wanted to save the environment!

..no not the russ form atherton... foster city actually. Bought my 914 a little over a year ago and i'm just now in the final stages of reassembly. Been ghostin' the bbs a long time but finally decided i needed to speek up.

Russ,

Let this be a lesson to you... LOL

When you ask a question around here... your standing a 98% chance it will be answered in less the 10 minutes. Of course I waited 2 hours.


B

I love Seattle, especially the waterfront. Used to live in Port Townsend. Made many a trip over the water in the super ferry. Had one job with a const. Co. that had me doing backhoe & dump truck work in downtown. My sister still lives there so I'll be up soon and, hopefully for the breakfast.
bruce

Twice the question was asked "What is the benefit of removing it", and nobody's responded to that. Come on slackers. Answer the man's question before starting the goof-off fest. (just kidding)

Decel valve - bleeds air into the intake on overrun (when you snap the throttle shut) to slow deceleration of the engine for emission purposes. Benefits of disabling - engine will spin-down more quickly making shifts quicker. Possible disadvantages - engine may spool-down so quickly when throttle is closed that engine speed may drop below idle speed momentarily causing stumbling or stalling. I say possible, because it's possible, but my experience is that the car runs great without it. I prefer to disable it. The efect on shifting is kind of like a fresh set of synchros.

-Ben M.

So, when you remove the decel valve, you just plug up the hole going into the intake and the one coming from the air box?

You got it! Actually, on mine, there was a small hose from the decel going into a "Y" just afer the AAR. It was that little skinny branch off the "Y" that was cracked and caused the vacuum leak. I tried some AB epoxy to close it up but that didn't work. I tried a new plumbing creation but that didn't work so I just took it out & no problems.
bruce

Hey thanks for the description ben. that helps.. i'll have this d-jet thang figured out soon enough!

I just noticed plugging the plennem-end is cool and easy.. but whats with VW designing a y-tube with each of the 3 tubes being a different size!?!? I'm guessing the only way of getting rid of that y-piece all-together is to use the bigger sized tube and hose-clamp it to the AAR?

Brad, when I was changing the oil I remembered your question about the ECU being where it is so I started looking for any tell tale signs of it ever being connected to the battery tray. My car has an air cond. compressor located in such a way that there is no room for the ECU where you described. It must have been done at the dealership???
bruce

They moved it because of the AC install.


B

I fully agree with airsix. The decel valve is only needed to reduce emission in the case of overun (e.g. driving down a hill). The valve is mounted in european cars as well, but i removed it due to two reasons:

1. number of potential air leaks is -1 ;-)
2. engine compartment looks better ;-).

The car runs great, even without the valve ...

benno