Confused : Double Vacuum on WUR 77 2.7 Weird Warm Control Pressure at Idle

strictly · 01:22 PM

First of all a big thanks to everyone who has helped so far.

Steep learning curve,i bought a real POS. My WUR was broken, and the injection wiring was cut and hacked, ive fixed all of that and set the WUR up for warm and cold.

Pics below :

Specs :

1977 911 2.7S
911/85 Engine
033 WUR
EGR, Therm Reactors, all removed (previously)
Cold Control Pressure (WUR unpluggeed, FP Running, Engine not, stone cold) 1.8 Bar CCP
WARM Control Pressure (WUR plugged heater in, FP Running, no vac on either line (engine not running ) 3.0 Bar WCP
WARM Control Pressure (WUR plugged heater in, FP Running, vac applied to top line (suck on it) 3.8 bar WCP

Im very confused by the double vacuum on my WUR because both pipes HAVE vacuum (engine running at idle). With both attached, my WCP goes richer to 2.4 Bar.

Maybe the clue is the Decel line to WUR? Should that not be TB to WUR??? See photos below. Also top hose of TB is blocked. Normal?

Ive read as many previous threads as i can, but i cant figure it out, as i thought only one hose on the WUR actually had vacuum, the other was a fresh air feed.

Its like my two vacuum hoses are fighting each other in side the WUR (by both pulling vacuum), and instead i get a richer mixture (2.4 bar warm).

strictly · 09-02-2015, 08:40 AM

bump?

Any ideas? If i disconnect the vaccuum line to the decel the one that goes to the wur, so its got a vacuum leak, the engine starts better

boyt911sc · boyt911sc's Garage

Strictly,

Where did you get those images (pictures)? They show the an incorrect routing of the vacuum lines from the decel valve. The vacuum line to the WUR should be coming from the top of the decel valve that comes from the vacuum line from the throttle body below the butterfly valve. And your WUR-033 should have the vacuum port on top of the WUR and not on the side. Keep us posted.

Tony

Targalid · 09-02-2015, 03:38 PM

Like Tony says, the vacuum line from the top of the WUR goes to the back of the airbox behind the throttle. The hose from the top of the decel valve goes to a T in the WUR vacuum line next to the decel valve.

strictly · 09-08-2015, 01:06 AM

Hi Guys thanks, for the replies.

Apologies to be delayed in replying busy with family life. I really appreciate the help. Ive got the engine into a drivable condition =) starting to enjoy it finally =))

Tony the pics are off my engine! My 033 WUR has two vac lines, one at the top and one on the bottom on the side. Currently the bottom one goes to the side of the decel valve as pictured and the top goes through the TTV/Dizzy/TB and fighting the vac on top very strange.

-----

Ok so i need to re route.

What confuses me is i have also found this information for a 77 from here, which has different vac routing. I'll try both (yours and diagram), although neither show the side decel routing, i cant find any info on that.

2.7 CIS WUR and Dizzy vacuum lines routing.

apparently for a 77

and slightly different

T77911S · 09-08-2015, 02:18 AM

you need to go read my post #9 on that thread. just because someone has posted pics does not mean they are correct. the top pic is WRONG and the bottom does not show enough to be right or wrong, but it can lead you more wrong than right.

the vacuum line for the 77 is on the top. the vac pulls the diaphragm up to increase CP. the port on bottom is just a vent to atmosphere.

the 2 big ports on the decel valve (DV) just bypass the thorttle plate. neither one should be Teed. the port on top of the DV is Teed. one line goes to the TTV then to the top of the WUR. the other goes to a port on the TB BELOW the throttle plate.

the vac retard on the dist runs directly to the TB. it goes to a port that is below the plate when it is closed but as soon as the throttle is opened that port is above the plate. just look down in the TB and you will see some tiny holes. just follow them back to ports on the outside of the TB.

you can run the bottom port of the WUR to something that is very hi on the TB. it is really there so that if gas leaks into the body it will go back into the intake.

there should be about a .8bar drop in pressure with the loss of vacuum to the WUR. make sure the TTV works. it should stay closed for about 20sec. its a really great device for added cold starting.

you can remove the DV if you want. its nto needed.

find a 3.0 TB. its a little bigger diameter. should give a little more on top end.

strictly · 09-08-2015, 02:23 AM

Tony, Targalid,

Is your routing based on the TOP wur connection being the vaccuum connection or the bottom/side being the VAC for the WUR?

When I had my WUR apart, the TOP connection is just a hole into the chamber. If i suck on it, when doing my warm control pressure test, it the WCCP goes leaner to 3.8, it pullss the valve at the bottom up/open, putting more pressure (compressing the springs) on the plunger.

When I had my WUR apart i noted that the side connection, If i suck on it, it cant do anything as the valve was fully seated - but if i blew through it, it pushed the valve open (up). I think this is the same thing as sucking on the top hose, it pulled the valve open.

Does this conclude that my top connection is my vaccum connection, and my side WUR connection is a "fresh air feed"?

I think i need to understand that first, before i can re-route my hoses, as it seems the 77 is a little peculiar.

Im not ignoring your advice, just working from the 77 diagrams/thread.

Part of the problem is i dont really understand the system, but im doing some back ground reading on this. So bare with me.

strictly · 09-08-2015, 02:25 AM

T77911S

Thanks ive just seen your post. We must have posted at exactly the same time. Im going to have a good read know. Thanks.

L

strictly · 09-08-2015, 02:37 AM

Quote:

Originally Posted by T77911S

you need to go read my post #9 on that thread. just because someone has posted pics does not mean they are correct. the top pic is WRONG and the bottom does not show enough to be right or wrong, but it can lead you more wrong than right.

the vacuum line for the 77 is on the top. the vac pulls the diaphragm up to increase CP. the port on bottom is just a vent to atmosphere.

the 2 big ports on the decel valve (DV) just bypass the thorttle plate. neither one should be Teed. the port on top of the DV is Teed. one line goes to the TTV then to the top of the WUR. the other goes to a port on the TB BELOW the throttle plate.

the vac retard on the dist runs directly to the TB. it goes to a port that is below the plate when it is closed but as soon as the throttle is opened that port is above the plate. just look down in the TB and you will see some tiny holes. just follow them back to ports on the outside of the TB.

you can run the bottom port of the WUR to something that is very hi on the TB. it is really there so that if gas leaks into the body it will go back into the intake.

there should be about a .8bar drop in pressure with the loss of vacuum to the WUR. make sure the TTV works. it should stay closed for about 20sec. its a really great device for added cold starting.

you can remove the DV if you want. its nto needed.

find a 3.0 TB. its a little bigger diameter. should give a little more on top end.

Ok. So that confirms my WUR TOP hose is my VAC as it does pull the valve up when I suck on it.

Ok moving to the next bit :

Ok i'll try that, this is in line with tony, and targa lid - sorry guys i really wasent ignoring you, just trying to get my head round it!! its easy to be mislead by other posts sometimes!

Ok starting with the decel valve. I move the T to the Top, where one bit goes to the back of the TB, and the other into the TTV, then out of the TTV and into the TOP of the WUR.

I now run the dizzy vacuum with no T, and run it straight to the bottom of the TB (on the front). Ive noticed this has port some vacuum at idle? Is that correct, it means the dizzy will be advancing ignition at idle?

Then i take the bottom/side connection for the WUR and run it to the top of the TB on the front (high) like you said

Ok i'll try that now.

strictly · 09-08-2015, 02:54 AM

Ok ive done it, i'll see how that drives. So to undertand the system a little better (for me). The WUR vac only works when the TTV is open. And the TTV valve only opens after about 20 seconds after starting?

Once the TTV is open, the WUR will have VAC on it, which will alter the Warm Control pressure, making it leaner.

Next step is im going to set the CO mixture, as i havent had this checked adjusted since before resetting my WUR for cold and warm pressures..