Which WUR is better or preferred? 089, 033, 045, others

[PeteKz]

WUR 089: SP= 4.8bar (70 psi)
CCP at 65F=2.0bar (30psi),
WCP without vacuum =3.7bar (54psi), with vacuum=4.2bar (62psi). This is above the spec.

WUR 033:
CCP at 60F=1.8bar (26psi)
WCP without vacuum =3.5bar (52psi), with vacuum =4.2bar (62psi). This is above the spec.

Although I measured the WCP as the same for both WURs, the 033 caused the engine to run one full AFR point leaner at all conditions, showing AFRs in the mid 15 range at cruise at from 60-80MPH, and the low 14 range at idle. See my post above for the AFRs on the 089. Both WURs displayed the same behavior during acceleration and deceleration, that is, the mixture initially went lean during acceleration (high 15 to 16 range), then dropped about 1 to 1.5 AFR point to a richer AFR (in the mid 14 range). And when I took my foot off the gas pedal, the opposite happened: First the AFR went rich, then leaned back to the upper 15 to upper 16 range. As noted above, this is intuitively opposite to what I expect and want.

I did not change the CO screw between changing the WURs, so I would expect that if the WURs have the same warm control pressure, that the AFRs should be the same. But as noted, they were not.

I noticed a very curious measurement when testing with and without vacuum. With a vacuum of only 0.1bar, the WCP went up about 12 psi, but as I increased vacuum to the Bosch specified measuring value of about 0.5 bar, WCP dropped back 2psi. That is, with the higher vacuum applied, the CP reduced a little! That is the opposite behavior of what I expect (more vacuum should push harder against the pressure regulator in the WUR and cause higher CP), so I checked it several times to be sure. Strange.

I'm also contemplating whether the M1 cam I have in my engine is sufficiently different than the SC cam that it affects WUR behavior. I may have to hook up a manifold pressure gauge in the cabin to see what that does as I accelerate and decelerate.

[boyt911sc]

Originally Posted by PeteKz

WUR 089: SP= 4.8bar (70 psi)
CCP at 65F=2.0bar (30psi),
WCP without vacuum =3.7bar (54psi), with vacuum=4.2bar (62psi). This is above the spec.

WUR 033:
CCP at 60F=1.8bar (26psi)
WCP without vacuum =3.5bar (52psi), with vacuum =4.2bar (62psi). This is above the spec.

Peter,

Both your WUR’s are no good. You should know by now that these WUR’s will only give you VERY LEAN condition. And make a bad situation worse by adjusting your fuel mixture to get a good AFR reading.

Calibrate your -089 and save your -033. Install a good working -089. This is a better mouse trap than -033.

Tony

[PeteKz]

Tony, now we are getting somewhere! You are starting to answer the original question I asked--which WUR is better to start with?

I already know these two WURs are out of spec--I said that several times. But the 089 does not run lean, it runs rich. And the warmer it gets, the richer it runs. I measured that with my AFR gauge. I know that doesn't make sense, but that is what I measured. I know that I did not do these tests back to back on the same day and same temperature, so maybe something else is causing this strange behavior. I will continue to investigate it.

Now, please go the next step: Is there a better WUR version than the 089 for a normally aspirated 3.0 or larger size engine? And what makes the 089 a better mousetrap than the 033? Please tell me how they are different.

In order to expand my knowledge, I will run the 033 for a few more days and make adjustments.

Thanks in advance, PK

[Mtsurfposse]

Pete
Did you ever find resolution to these inappropriate AFR values under load? I have the same 089 in a 3.0 ROW. I experience the lean you described in first posts here. I suspect the vacuum routing is wrong.

I’ve searched an and found many different potential diagrams but not one that says Yes! This is 089 vacuum routing for non lambda
It was routed top of WUR to upper throttle body nipple on drivers side (1)
Lower chamber to thermotime and from there to T at decel valve to front of car nipple(3)
(1) has no vacuum appears to be atmospheric
(2) nipple, just below 1 on the drivers appears to be true manifold vacuum as it pulls vacuum at idle and drops with throttle
(3) pulls vacuum at idle and under throttle
(4) goes to my distrib and I’m guessing is doing fine
As the car generally runs great

Do you have a diagram that worked for you and gave you STRONG enrichment at WOT. The best for me is shutting off the vacuum to the lower port of the WUR which gives me rock steady AFR At whatever I set enrichment to

[PeteKz]

Sort of.

After messing with both WURs, pulling off the throttle body several times to trace where those nipples actually go, and experimenting with different locations for vacuum signal, I settled on using vacuum directly from the intake manifold, rather than the throttle body. I currently have the 089 WUR installed, and it provides enrichment at high throttle (low vacuum) and high RPM. It behaves about like what I expect. Not perfectly, but close enough.

I don't have a diagram, and I'm not in my shop now, so I'll describe where I take vacuum to the TV and to the WUR. On my CIS, there is a fitting on the left side of the air box, just above and forward of the left intake runners. It goes directly into the intake manifold of the air box. I had a fitting that screwed in there, that has a 1/4" nipple. So I connected the vacuum line to the TV and WUR there. That way I KNOW I'm getting load-related intake vacuum signal to the WUR. And the AFRs seem to work better that way. Try it.

(1) Yes, the cast nipple on the top of the WUR goes to that nipple on the top drivers side of the TB, and it is just an atmospheric vent. It goes there becuase at that point, the air has been filtered, so the WUR won't get dirt inside of it. A slight amount of vacuum is present at that vent nipple, but it's better than unfiltered air.

(2). The nipple below #1, is not vacuum, it's "ported vacuum" intended for the retard side of the distributor can. It should provide a vacuum signal at idle and low throttle settings, and reduce as RPM and load increase.

(3) also is ported vacuum, but different than #2.

(4) Supposed to be manifold vacuum, but from my fiddling, it doesn't quite act like it. This nipple goes to the advance side of the dizzy can. I have my dizzy connected there too.

[Mtsurfposse]

Thanks, The plot thickens

I tried using 2 isolated and that didn’t work.

I do have a few related posts going that ive just realized are related. You commented on my “easiest warm WUR adj in the road” and thought that a simple on off valve shouldn’t work with modifying pressures. But what I’m thinking is that it SHOULD,… EXCEPT the vacuum once applied to the WUR cannot release. It should, through the top port and the number 1 nipple.

Maybe your WUR experiences what mine does so that if you apply test vacuum to the lower WUR it will hold vacuum indefinitely until the seal is broken. I’m thinking this X manifold valve you found reaches tru atmospheric at some point allowing the diaphragm to fall and control pressure to fall.

I will hunt for your nipple X, but try testing your WUR and keep an eye on my 089 WUR vacuum testing pst. I’m hoping Tony chimes in soon, as he rebuilt my WUR and he should know how these should be tested and behave related to the vacuum

[Mtsurfposse]

Nipple X? This one? X

I think this heads to the AAR or AAV

[boyt911sc]

MT,

There are numerous vacuum diagrams for ‘78~’79 posted in this forum that people had been using. It would be helpful to post some pictures for references during discussions. One good example is that front of the engine could be the rear or vice versa. When I look at the engine orientation after opening the engine lid, I refer to the section closer to the rear bumper as the front side others call it differently.

My next question just to be clear we are on the same page, which is the front side of the throttle body in your car (911)? The section closer to the rear or front bumper? Thanks.

Tony

[Mtsurfposse]

Tony,
I agree about the lack clarity, a worldwide convention would be great. I refer to front as towards driver, rear towards rear bumper.

The issue Petekz and I have had is lean mix with engine load… so reduced intake vacuum not having an effect on WUR/control pressure

I was thinking it was an improper routing of vacuum lines BUT I’ve tried to different (appropriate) routing of lines and they act as they should. Higher vacuum at idle, reduced vacuum with throttle increase.

Regarding vacuum diagrams, I’ve tried two ways of common orientations. From port at front of engine to T at decel to TV to WUR

From drivers side of engine lower port to TV to WUR this one seems to pull a lower volume of air

So my WUR gets vacuum at idle, and the vacuum decreases at idle but the WUR doesn’t respond unless I disconnect the vacuum hose, at that point control pressure will drop.

You performed some work on this WUR while the car was with the previous owner SkiVT
But I’m not if it was a rebuild or just a tune. I was thinking I would pull it apart to see if the vacuum pin is hanging up or the diaphragm was inhibited

[boyt911sc]

Originally Posted by Mtsurfposse

Tony,
I agree about the lack clarity, a worldwide convention would be great. I refer to front as towards driver, rear towards rear bumper.

The issue Petekz and I have had is lean mix with engine load… so reduced intake vacuum not having an effect on WUR/control pressure

I was thinking it was an improper routing of vacuum lines BUT I’ve tried to different (appropriate) routing of lines and they act as they should. Higher vacuum at idle, reduced vacuum with throttle increase.

Regarding vacuum diagrams, I’ve tried two ways of common orientations. From port at front of engine to T at decel to TV to WUR

From drivers side of engine lower port to TV to WUR this one seems to pull a lower volume of air

So my WUR gets vacuum at idle, and the vacuum decreases at idle but the WUR doesn’t respond unless I disconnect the vacuum hose, at that point control pressure will drop.

You performed some work on this WUR while the car was with the previous owner SkiVT
But I’m not if it was a rebuild or just a tune. I was thinking I would pull it apart to see if the vacuum pin is hanging up or the diaphragm was inhibited

Mtsurfposse,

No wonder I could not find your name in my logbook. And your screen name did not ring a bell at all. Now that you mentioned SkiVT, I did rebuild his WUR. The previous owner is an excellent CIS troubleshooter and could help you a lot.

You mentioned about your vacuum connections for the WUR-089 is questionable. If you could post picture/s of the routing of the vacuum hose for the WUR, I could tell if they are correct or not.

Second, why were you putting pressurize air (low) to the vent port on top of the WUR for your test? It does not makes sense. Plus installing a shut-off valve to the vacuum line to WUR? I read that post the first day you posted it and had to control myself from getting involved.

What are your WCP (warm control pressure) with and without vacuum? Thanks.

Tony

[Mtsurfposse]

warm pressure/ no vac. 2.8
Warm pressure with vac 3.75

My issue is lean running under WOT. The vacuum pressure that creates the higher control pressure does not bleed off. So there is no connection between the upper WUR port (atmospheric air) and the lower port. So once vacuum is applied to the WUR, it remains at the high control pressure and so a lean condition arises.

With the shut off valve I can artificially keep the mix rich. As to blowing air into the WUR top port, similarly I’m trying to figure out why the WUR holds a vacuum indefinitely instead of temporarily.


I’ll post pics of the vacuum lines later, but they are run in the stock manner AND the ports are functioning as they should. Higher vacuuum pressure at idle, lower with throttle.

As to the previous owner. He’s great, and he spoke super highly of you too! I do call on him when I have questions but this LEAN issue was one he said he never sorted out, he had tried but never found an answer and I’m hoping to get to the bottom of it

[PeteKz]

MT: Yes, that's the place where I have a nipple. It's for the vacuum for the power brakes. My 1973 car does not have power brakes, so was capped off, and I used it for a true manifold vacuum signal. As I said, it seems to make the WUR work better.