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

@Ian Stott

For L jet or D jet ?
Can you post the number on yours?
Bruce

Bosch 022 133551

I thought I would bring this back to the top, as I have not had any response to the soaking the valve in kerosene or WD 40 suggestions. Maybe my title was misleading in that many saw it as looking for a deceleration valve, of course I am looking for one but just as important is the question has anyone does this and what were the results?

Thanks!

Ian Stott
Moncton
Canada

I was alittle confused reading what you were doing with the decel valve. I haven't heard of people soaking a decel valve before, maybe soaking a aux air valve. I wouldn't think there's much inside a decel valve other than a large rubber diaphragm.

Have you tried turning the adjustment screw to loosen things up then readjusting the decel valve to open at the vacuum setting you want? Maybe blow some air in there to clean out any debris.

we try the wd40 first then buy a used one

Click to view attachment

Do you have one I could purchase?

Ian Stott
Moncton
Canada

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

I’ll be interested in your results.
I’ve got one that leaks but only after driving the car for 15-20 minutes or so. I’d like to keep mine connected as I’ve read they help reduce strain on the MPS but mine is disconnected for now.

Thanks, I will wait to hear from you!

Ian Stott
Moncton
Canada

I'm curios if you understand why you need it? Why do you think you do?

According to the mechanic working on my car it controls the vacuum, so when not working you can have backfiring on deceleration, which I have. Also it is not possible to set the idle correctly with it being plugged. I am sure more knowledgeable people can explain the need for it better than me! I am also pretty confident it is there for a reason or Porsche would have not put it in the car.
My mechanic is an ASE from Belgium, has worked on these cars before emigrating to Canada; until I found him I was on the verge of switching to aftermarket fuel injection.

Ian Stott
Moncton
Canada

It doesn't "control the vacuum" (if I understand you correctly); it uses manifold vacuum to open itself, to add un-throttled air to the intake to lean it the mixture on decel to reduce backfire (and excessive emissions) due to a rich mixture.

Modern EFI simply backs off the injector pulse (or shuts off the injectors entirely) when the throttle is closed (as indicated by the TPS) and on engine over-run to lean out the mixture. For whatever reason, D-Jet was not able to do that back then (or maybe they didn't think of it?)

Testing the decel valve is fairly straightforward. With no vacuum on the port, the valve should be closed and you can't blow through it. Adding a vacuum via a Mity-Vac and the valve should open and you can blow through it. As I recall the desired setting for that cutover is 17mmHg?

If you can blow through it when it's off the car, and/or cannot blow through it with vacuum on it, then it's bad and/or out of adjustment. I wouln'dt be surprised if a prior owner danked around with the adjustment...

If it works fine but the cutover vacuum is either too high or too low, then it can be adjusted via that locknut and screw to ~17mmHg.

What are your current symptoms when testing in this manner?

Ljet on a 2056 engine with a #73 WEB cam.

Ian did you get your starting issue sorted out?

I checked but did not find that I have any decel valves.
Found this on Brad Anders site

Porsche number 022 133 551 Bosch 0 280 160 102 1.7L 1972 - 1973

1970 -1971 1.7L 914's didn't have a decel valve, because their ECU cut off the fuel flow on overrun.

Bruce

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.

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.

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

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

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

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.

The decal valve is a different beast for the L-jet,I have one and it looks like this;
Click to view attachment
The same unit is used on 1.8/2.0 bus and I think aircooled T25.

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.

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.

Decal valve is featured on page 53 of the Haynes manual,shows a pic and explains how to test it .

One for sale on eBay

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

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

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.

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.

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.

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 Click to view attachment Click to view attachment

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,

@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.
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?

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.

Thanks, @Van B!

@Van B

the EGR on the 75 (calif) works off the vac port before the throttle plate on the throttle body when its all hosed up proper stock.

one of those weird things i discovered on the EC-A, EC-B research.

same port worked advance on the distributor of the EC-B 74 engines.

the decel on the 75s still works the same way as it did on the 74s.
off manifold vac.
but its a beefier unit for sure.
maybe letting in even more air on decel than the 74s?

Yeah I saw the T on the parts diagram and rather than try and figure out what was going on there, I was just glad I got a ‘74. I’ll be honest, I knew I wanted a 1.8L L-Jet when I was shopping, but I had no idea how much junk was on a ‘75 model.
I learned to drive in a ‘75 1.8, but all the 75’s I ran across in my search were either 2.0, carb’d, or both.

Egr is actually a really cool (literally) addition to engines. My 302 runs so much better with the egr working (correctly). For a hot little beast like these flat 4s egr could really help keep them cooler while cruising.

as it turns out we know we got the best one. the EC-B. least crippled.

maybe you learned on a 49 state 75. nearly as pure as an EC-B. just didn't have the advance on the distributor connected.

i'd like to have sympathy for californians. they get experimented on.
but its their own fault?

you know your stuff emery.
EGR was a kind of substitute for the advance hose hook up on the EC-B of 74.
i believe the EGR also enhanced fuel economy slightly at cruise as well as the cooler running, restoring some of the benefit of the EC-B vac advance operation from distributor.

as far as i can tell the EGR on the 75 californians only kicked in really at cruise, steady part throttle. rest of the time it was out of the equation.

there were a variety of throttle bodies on the L jets.

we got the research done on them.

EC-B (49 state) 74 had both ports and both vac lines (adv + retard) connected to dist.
EC-A 74 (cal) had no connection of advance vac line to throttle body and port capped in throttle body in front of throttle plate. only retard connected.
75 EC (49 state) had only one port in throttle body. connected to vac retard on dist.
75 EC (calif) had both ports on throttle body. had retard connected on dist.
and had same port as EC-B in front of throttle plate connected to EGR.

finally got to the bottom of it all.

and all the different stories about them being two ports or one port, advance + retard,
or only retard.

folks saying one or the other were right (and wrong) in the past.
only had part of the story.

jeff bowlsby opened up the question recently and we cracked the mystery.

which means yeah.
a californian EC L jet coming down off throttle closure with or without a decel might behave slightly differently to a 49 state EC coming down off throttle with or without a decel? ??

i have a 74 EC-B. no decel. has had no decel for 33 years at least. no problems.
except when cold. rest of time i must admit i really like how it comes down when i back off the gas. no backfires either. which aren't backfires anyway. its fuel dumping in the hot exhaust and detonating. never get that. sometimes can hear a slightly burble.
but its pretty mild. keep it well tuned which might help.

yes i know there are some say you have to have them.
and i don't disagree. might even reinstall a decel just to see what its like as i have found one and have it racked and stacked. but for now. all is fine.

you certainly do need them for D jet.


EDIT.

here is stuff i pulled off an old 911 intake system.
think its for a K jet?
salvaged a decel valve and probably only have to adjust spring pressure for the 914.
bracket is wrong orientation but probably adaptable.

Click to view attachment

also have an aux air valve, which looks almost like a 75 decel valve. (almost but not quite)
the aux air valve is hooked up to an aux air regulator, which is what we would call an aux air valve on the 914. they seemed to need to use the two to do cold start extra air for warm up.

they just made these kind of standard parts and they had a nipple closed or open, or a diapram maybe stiffer or a spring adjustment different and used them on anything and everywhere.

in australia there is a mob in queensland who can rebuild these things.
they open them up and recrimp them, so long as they are made of metal.
so if your WD 40 trick doesn't work and you can't get hold of one down here, they are a good way to go here if you have a core you can send them.