Vacuum connection on WUR

[carrera73rs]

Hello

I was doing a heat backdate on my 81 911sc, I believe I broke the plastic nipple off the top of the WUR which runs to the thermo valve, now the vacuum line isn't connected.
After doing the backdate I started it to take it for a drive, started no problem, but as it warmed and RPM's came down it stalled. Fired back up easily, and as long as I have it above 1500RPM with foot on the pedal it runs fine, if not it stalls immediately.
Any ideas if this could be related, if not, any other ideas it could be?
Up until this it ran flawlessly.

Thanks

[SkiVT]

What are the last 3 digits from the part number on your WUR. (089, 090, etc)?

[carrera73rs]

I am now hoping that I used the correct terminology and right part.
I could not find a number other than the ones in the picture, it has not been removed from car yet.

[boyt911sc]

Stubby,

Right below where the white plastic nipple broke is the Bosch ID number. It should read like this: 0 438 140 xxx. The last 3 digits will identify your WUR. If you have a USA/CAN spec., the WUR should have -090. This is a non-vacuum assisted type WUR and that hose is connected to a vent at the throttle body.

What happened after you broke the plastic nipple was allowing unmetered air get into the system. And will cause havoc to your mixture. Keep us posted.

Tony

[carrera73rs]

Thanks

From what I can see it looks like 090.
What can be done to fix this, can I just plug the hose and/or nipple, or if it just runs to a vent does it matter?
Could this unmetered air cause the issues I am having?

[LM3929]

I have an extra one you can have for the postage cost.

Lorne M.

[carrera73rs]

email sent

[carrera73rs]

All

I tried a quick fix this morning, hoping it would fix the problem so that I don't have to look any further.
Engine started up no issues, it was cool this morning 32 F, quickly settled into an idle at 1800 RPM, as engine warmed RPM dropped as usual, just above 1000 RPM engine started to sputter and then died.
Would not keep the idle.
What else can I look at?
Nothing but the cooling tin was changed out.
Ideas?
Thanks.

[pmax]

What's the quick fix that you tried ?

[LM3929]

Try and turn the idle adjustment screw out about 1/2 to 1 turn and see if your car will idle, if it does. remove the oil fill cap and see id the idle goes up and let us know wht happens.

Lorne M.

Ps the fitting probably will be off tomorrow

[carrera73rs]

Quick fix was to tape the broken plastic fitting together, remove any unmetered air

[carrera73rs]

Lorne - adjusted idle, same issue

[Brian Cameron]

That may not be not a vacuum line, but rather, vent to atmosphere.

Trace hose 16 in the diagram below and you’ll see the restrictor 17, the thing that broke, for some reason the diagram shows it being a long way from the WUR but like yours, mine is an inch or two away because hose 16 is very short. After 17 it changes to hose 13B, follow the dotted line and you’ll see it enters the throttle body on UPPER port. That is above the throttle butterfly valve and is not vacuum, but “atmosphere” for venting.

Does your detached hose follow the same path as the diagram, ie to the upper nipple on the throttle body? If so, it’s not vacuum, but open air. If so, don’t plug the broken restrictor 17; in a pinch you could temporarily leave it open to the air if taping it back to the detached hose doesn’t work. But don’t leave like that for too long as dirt & wet could get into the WUR

[carrera73rs]

Brian

The diagram you attached shows a WUR, but not the one that is installed in my 81, the picture in PET may be from an 1983 model.
The attached picture shows mine with the green circle around my broken part which runs to the throttle housing, the yellow circle around an electrical connection and the blue circle around a fuel connection which runs to the center of the fuel distributor.
Could this be as simple as a mixture issue, not that mixture issues are simple.

Thanks

[Brian Cameron]

I have a 79 and my WUR (045 version) plumbing is identical to the PET diagram, except the PET diagram is missing the electrical connector that we both have.

Looking closer, your WUR 090 version appears to be missing the nipple off the side of the WUR, which on mine is connected to vacuum via the Thermo Valve (17A) although mine no longer has the decel valve (7).

You don’t have an open hole on the side of the WUR any chance? When i pulled that vacuum hose off my WUR the nipple fitting came with it. If yours became detached that might explain why it’s missing. Or yours may not have the vacuum connection at that location because it is a different design... unfortunately I’m only familiar with my own WUR but i know there are variants out there.

The hose out the top on mine is vented to air, ie at the upper nipple on the throttle body. Where on the TB does your broken hose connect? If it connects to the TB above the butterfly, presumably it’s air. If it connects below the butterfly valve in the TB, it’s vacuum and it probably connects through the decel valve (7) if yours is still installed. In which case your broken hose is a vacuum leak that could be causing your running problem, further compounded by the WUR not getting vacuum.

[boyt911sc]

Brian,

You have a WUR-045 which is a vacuum assisted type (vacuum port at the side and vent on top). While the OP (Stubby) has a WUR-090 a non-vacuum assisted type. They are totally different WUR both in configuration and operation.

This is another reason why people get confused about CIS because people don’t understand or realize which component they have on their system. Yours is a non-lambda system (OXS) compared to Stubby’s. Two different CIS systems.

Tony

[Brian Cameron]

Tony, glad you chimed in, somehow i missed your earlier post. I did suspect there was a difference between the 045 and 090 WUR but unsure what.

I now see the flaw in my logic, even if his broken hose is not vacuum, it’s letting air sneak in after the air flow meter and that puts mix out of whack.

So could OP do a temporary fix by plugging the hose? That would stop the unmetered air leak and the WUR shouldn’t care, since it doesn’t need vacuum? Or am I missing something else in the equation?