Deceleration Valve Options

[GregAmy]

OK, so if it's an L-Jet like Mark says, and the L-Jet doesn't have one per Bruce above...what are we walking about?

If you're looking for a D-Jet decel valve, I likely have an extra in my parts stash.

First, you should verify what you have.

[Mark Henry]

Ian has a '74 Ljet, complete system and dizzy known at the time to have no issues. The system is from my 1.8 914 that I converted to a /6, about 80k miles on the system. The engine is a 2056cc with a #73 Web camshaft, KB pistons and 2.0 heads, the rest is stock.
I'd have to check but IIRC it was 4 years ago.

At that time it ran perfectly, but IIRC the best it would do was 800rpm at hot idle. Only odd thing was it needed 2-3 pumps on the gas to start, with my stock 1.8 it didn't need this. Power I couldn't tell any difference between it and a stock Djet.
Ian drove it home, an 18 hour trip, if Ian lived closer I'd likely be the one trouble shooting this.

[Ian Stott]

I appreciate all who chimed in, would like to know what kind of success anyone has with soaking the valve in WD 40 or kerosene.

Thanks

Ian Stott
Moncton
Canada

[cary]

I have 2 soaking in kerosene right now. I'll drain, dry and let you know the outcome.

One freed up. $$$$. One didn't.
The didn't went back in the sauce.

[Rand]

It's like an appendix. You could just remove it and not care.

[GregAmy]

I don't know the L-Jet system...but Bruce says above that L-Jet does not have a decel valve. I Google "Bosch 022133551" I see "Decel Valve 1.7 1.8 914" and "914-4/1,7. 914-1,8/2,0."

http://www.autoatlanta.com/Porsche-022133551-srch.html
https://www.porscheatlantaperimeterparts.co.../022133551.html

Anders states, "1970 -1971 1.7L 914's didn't have a decel valve, because their ECU cut off the fuel flow on overrun."
https://members.rennlist.com/pbanders/DJetParts.htm

So does L-Jet have one? Looks like it's the same for all engines.

I found it interesting that some listings described it as a "Vacuum Limiter Valve". And I guess that's true, in a circuitous sort of way; by bypassing the throttle plate to add intake air, you are increasing manifold pressure/"limiting vacuum"...

Ian, I suggest asking the tech to test your decel valve as I described above. I'll rummage my parts stash tonight for a spare and if the tech finds yours is not properly functioning then let me know.

[porschetub]

OK, so if it's an L-Jet like Mark says, and the L-Jet doesn't have one per Bruce above...what are we walking about?

If you're looking for a D-Jet decel valve, I likely have an extra in my parts stash.

First, you should verify what you have.

The decal valve is a different beast for the L-jet,I have one and it looks like this;

The same unit is used on 1.8/2.0 bus and I think aircooled T25.

[rjames]

If the car is backfiring it’s not the decel valve’s fault. Your mixture is too rich, too lean, or you’ve got a leak in your exhaust system.

Lots of people ditch the decel valve. But people with way more knowledge than I have stated that doing so may result in putting more stress on the MPS, which is an expensive part to replace. There are rebuild kits for the MPS, but either replacing or repairing will require an AFR meter and specific tools to correctly calibrate it for your engine.

[Bleyseng]

My 77 Baywindow Westy has the Ljet with that Decel valve and it still has the fuel cutoff on over run in the ECU. The Decel valve must be a emission device to add extra air when the throttle is closed on over run.

[porschetub]

OK, so if it's an L-Jet like Mark says, and the L-Jet doesn't have one per Bruce above...what are we walking about?

Decal valve is featured on page 53 of the Haynes manual,shows a pic and explains how to test it (IMG:style_emoticons/default/confused24.gif) .

[JawjaPorsche]

One for sale on eBay

https://www.ebay.com/itm/Porsche-912-914-1-...moAAOSw7vBdo-St

[porschetub]

Classic bad ebay listing ,not the unit we are talking about here.

[ClayPerrine]

It's like an appendix. You could just remove it and not care.

Bad move. The decel valve opens when you close the throttle at high RPMs. It leans the mixture, and also it acts as a dashpot, keeping the RPMs up so the engine doesnt die under decel.

And all of the 1.8L engines had them. Brad is an expert on the D-Jet system, and I will always defer to him on it. He has studied it extensively. I don't believe he has studied the L-Jet system as extensively. I have worked on them for 34 years, and every one I have worked on, as well as the PET parts manual, lists a decel valve for both years of the L-Jet system. And the only difference between the ones for D-Jet and L-Jet is the adjustment setting.

[porschetub]

It's like an appendix. You could just remove it and not care.

Bad move. The decel valve opens when you close the throttle at high RPMs. It leans the mixture, and also it acts as a dashpot, keeping the RPMs up so the engine doesnt die under decal.

(IMG:style_emoticons/default/agree.gif) good description,my understanding is the L-jet TB's that have only one vacuum port (retard) so that valve would be essential to stop stalling when the throttle is fully closed after acceleration ,right ?
So it serves the above function and also helps to reduce emissions when the throttle is closed @ the same time ?.
Cheers.

[rjames]

Reviving a bit of an old thread and maybe this is well-known already, but the Porsche 911 1978-83 decel valve seems to be identical except for the way the mount is attached to it.

The 911 part can still be mounted, but you have to angle the end of it up for the hose to the air cleaner box to clear the MPS because the way the mounting bracket is connected to it puts the side port pointing down directly towards the MPS.

Maybe I got lucky, but I found a NOS one on ebay for $40.

[RandyE]

This is a very difficult to get item to get! Many have said soaking the existing one in kerosene for a few days will do the trick, have not done that yet as I am still trying to track down a new one. Wondering what the success rate has been with soaking it in kerosene, also wondering would WD 40 do the same thing. Would hate to ruin the one I have, which is original to the car!

Ian Stott
Moncton
Canada

Hey I'm new here and stumbled across this forum and topic. Also a new 914 and air cooled beginer! So i registered and wanted to share my fix. I was amazed i couldnt find much info on this topic so wanted to share what i came up with. I used a faucet handle /compression sleeve puller inserted into the large diameter end port to gently work the piston and spring free (after letting some wd-40 soak that port for a few minutes). I could then pull a vacuum on the small port and push compressed air through the other ports. I hope this helps anyone else with a stuck decel valve! Just for reference the ports begin to equalize at 15 in/merc and fully open at about 18in/merc. I dont know what they are susposed to be, but thats where i am at! Car sat for about 30years and im the second owner. Hope this helps! Randy

[Van B]

Randy, I posted about this in a different thread regarding a high idle problem I was having. I found that adjustment of the screw (in) so that opening begins at 20” solved my idle hang issue.

Also, (IMG:style_emoticons/default/welcome.png)

[StarBear]

@Van @ClayPerrine Looking to get a backup/spare for my 1.8 and came across this oddity: the part number I have is 022133551 (via sources and the original that's on my car now), but a) every source I've seen shows its for a 1.7 and b) one source indicates a "B" version for the 1.8L. Never seen/heard of the "B" version before. (IMG:style_emoticons/default/dry.gif)
Wondering if they're really all the same just maybe different vac settings? Cleaned and lubed mine and reset to 19.5" (all the way in as probably by now a really weak spring).
Your braintrust thoughts? (IMG:style_emoticons/default/smile.gif)

[Van B]

The parts manual can be a little weird on our cars due to the change in ‘75 that introduced the extra emissions junk.

But the one you have is the correct original as you know.

I had success finding a replacement by searching the Bosch number vs the VW number.

The B version is for ‘75 and it’s larger for egr purposes I assume.

[StarBear]

Thanks, @Van B!