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Want to raise boost AFR - I have a WUR adjustment question

Hey there Pelicans,

I would like to raise my boost AFR. I've got my CCP and WCP right where I want them however the engine is running too rich in boost. Right now my AFR goes into the low 10s or sometimes even high 9s under full boost. I'd like to get the AFR into the 11s or low 12s.

I think I can raise my boost AFR by pushing the plug in on the bottom of my stock '87 WUR. Is this correct?

I've already been adjusting the CCP and WCP plugs on the top of the WUR. I've got that figured out no problem. However before I move the plug on the bottom I want to verify with the Pelican braintrust that indeed by pushing in the plug on the bottom of my WUR my in-boost AFR should start to raise.

Here is a picture of the bottom of a WUR. Mine is similar except mine does not have the hole in the middle of the brass plug. The brass plug is what I'm thinking I can push in to raise boost AFR (adjusting boost control pressure).

Thanks for any help you can provide!

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'87 911 turbo, '10 Cayman S
In the past - '71 T, '77 S 3.6, '80 SC, '88 3.6 cab
Old 12-16-2013, 07:20 AM
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Yes this will be the way.

Small movements make a big difference so do it in small steps.

Let me ask, at 10 to 1 AF ratio under boost, does the car feel sluggish or miss at all?

I am trying to establish a minimum AF ratio value where the combustion process starts failing.....as my car starts to miss at those levels. I was wondering if others see the same levels.
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, B&B intercooler, Snow Perf water/meth injection, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.7bar max
---"When you're racing it's life! Anything else either before or after, is just waiting"
Old 12-16-2013, 08:53 AM
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Maybe you have already thought of this, but a tip I read about here, posted by JFairman, is to use a large c-clamp to push the plug inward (most suggestions you read will say to punch the plug inward with a drift and hammer, but I found it is much easier to move it, in a controlled manner, using the c-clamp method).
Old 12-16-2013, 09:19 AM
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Quote:
Originally Posted by fredmeister View Post
Let me ask, at 10 to 1 AF ratio under boost, does the car feel sluggish or miss at all?

I am trying to establish a minimum AF ratio value where the combustion process starts failing.....as my car starts to miss at those levels. I was wondering if others see the same levels.
At anything below 10, on full boost, mine starts to misfire/bog down, and at 9.5-9 it misfires so terribly that it stops accelerating entirely.
Old 12-16-2013, 09:21 AM
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Quote:
Originally Posted by fredmeister View Post
Yes this will be the way.

Small movements make a big difference so do it in small steps.
Thanks fredmeister for confirmation of the boost control pressure adjustment.

Quote:
Originally Posted by Ronnie's.930 View Post
Maybe you have already thought of this, but a tip I read about here, posted by JFairman, is to use a large c-clamp to push the plug inward (most suggestions you read will say to punch the plug inward with a drift and hammer, but I found it is much easier to move it, in a controlled manner, using the c-clamp method).
Yep that's what I'll do.

Quote:
Originally Posted by Ronnie's.930 View Post
At anything below 10, on full boost, mine starts to misfire/bog down, and at 9.5-9 it misfires so terribly that it stops accelerating entirely.
This is exactly my experience as well.
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'87 911 turbo, '10 Cayman S
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Old 12-16-2013, 10:05 AM
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I have another question about adjusting the boost control (enrichment) pressure. If I push in the brass plug on the underside of the WUR (as described by Ronnie's.930 above) does this adjustment have any affect on the warm control pressure?

Based on JFairman's post #4 in the link below I do believe adjusting the boost enrichment pressure will affect the warm control pressure:
What's your difference between Enrichment and Warm Control Pressure?

So if I raise the boost enrichment pressure (raising boost AFR) by pushing the brass plug in on the bottom of the WUR will this adjustment also raise or lower the warm control pressure?

Thanks again for the help!
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'87 911 turbo, '10 Cayman S
In the past - '71 T, '77 S 3.6, '80 SC, '88 3.6 cab
Old 12-16-2013, 10:20 AM
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Quote:
Originally Posted by Ronnie's.930 View Post
At anything below 10, on full boost, mine starts to misfire/bog down, and at 9.5-9 it misfires so terribly that it stops accelerating entirely.
That's how I remember it as well.
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Old 12-16-2013, 11:02 AM
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Quote:
Originally Posted by Kaefer View Post
I have another question about adjusting the boost control (enrichment) pressure. If I push in the brass plug on the underside of the WUR (as described by Ronnie's.930 above) does this adjustment have any affect on the warm control pressure?

Based on JFairman's post #4 in the link below I do believe adjusting the boost enrichment pressure will affect the warm control pressure:
What's your difference between Enrichment and Warm Control Pressure?

So if I raise the boost enrichment pressure (raising boost AFR) by pushing the brass plug in on the bottom of the WUR will this adjustment also raise or lower the warm control pressure?

Thanks again for the help!
No it wont.
This plug just acts as a hard stop to limit the travel of the diapragm for the boost enrichment circuit. This limits the final boost control pressure value that can be reached.
Turning the 4mm allen head screw which is accessed thru the hole in this plug is how warm control pressure is adjusted mainly. Unfortunately when adjusting the warm control pressure you will effect the boost control and will have to go back and adjust the plug again.
Who modified your WUR like this? Thats not the "standard adjustable WUR" that most others are using. Its good to see different ideas to the same problem.
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, B&B intercooler, Snow Perf water/meth injection, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.7bar max
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Old 12-16-2013, 11:26 AM
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Quote:
Originally Posted by fredmeister View Post
Who modified your WUR like this? Thats not the "standard adjustable WUR" that most others are using. Its good to see different ideas to the same problem.
fredmeister the pic above is not my WUR. I just used it to show a pic of the plug I wanted to move to adjust boost enrichment.

Based on what you are saying I'm thinking I'm in good shape with leaning the boost AFR without the adjustment affecting warm control pressure. I'll push the boost enrichment plug in tiny increments then verify how the adjustment affected boost AFR. I'm sure like all these adjustments a little goes a long way.

I've been adjusting pressures with my stock '87 WUR. Leask was closing up shop when I wanted to start making adjustments so I decided to start adjusting my "stock" WUR. There is lots of info on the web regarding adjusting cold pressures on unmodified WURs but not so much on warm and boost pressures adjustments. So I've been learning as I go and making adjustments on my "stock" WUR.

My method of adjusting warm control pressures has been to move the big plug on the top of the WUR. My stock WUR does not have a hole in the bottom brass plug (boost enrichment). Of course now I'm wondering if that 4mm allen screw is under the boost enrichment plug (it's probably there) and if so now I'm considering drilling a hole in the plug to allow that warm control pressure adjustment using the allen screw. Adjusting WCP with that allen screw would be MUCH easier than adjusting the position of the big plug on the top of the WUR.

Below is another pic I posted awhile back (also not my WUR). As I said above adjusting WCP via the allen screw would be MUCH easier than adjusting WCP with the big top plug.

Thanks again for the help. I've got cold and warm pressures where I want them with my "stock" WUR. Now I want to get my boost enrichment AFR a little leaner. I'll be happy with mid 11s vs. the 10s and 9s I experience now.

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'87 911 turbo, '10 Cayman S
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Old 12-16-2013, 12:42 PM
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Tapping in the top plug for warm control must be a *****. Mine is tight.

Definitely the way to go is turn the allen screw thru the hole in the brass plug. You have much finer control over warm and boost pressure this way.

So I guess Leask is in retirement now.
Hats off to him for designing a system that allows us CIS diehards to tune our cars.

I am looking for the next great entrepenaur to redesign the air metering cone shape in the interest of giving us more ability to tailor the AF ratio for our modded engines.

later,
Fred
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, B&B intercooler, Snow Perf water/meth injection, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.7bar max
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Old 12-16-2013, 01:04 PM
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Quote:
Originally Posted by fredmeister View Post
Tapping in the top plug for warm control must be a *****. Mine is tight.

Definitely the way to go is turn the allen screw thru the hole in the brass plug. You have much finer control over warm and boost pressure this way.
After getting the hang of adjusting the small top plug for cold pressure adjusting the big plug isn't too bad.

One more question - if I drill a hole in the bottom plug (boost enrichment) to be able to adjust the warm pressure via allen screw --- do I need to then plug the hole I just created or just leave it open? My guess is I can leave it open.

Also to summarize - I can adjust boost enrichment by tapping in the lower plug (raising boost pressure/AFR) and this adjustment does not affect warm control pressure/AFR. However adjusting warm control pressure affects both warm AFRs AND boost enrichment pressure/AFR.

This is good info. Thanks.
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'87 911 turbo, '10 Cayman S
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Old 12-16-2013, 01:16 PM
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Quote:
Originally Posted by Kaefer View Post
After getting the hang of adjusting the small top plug for cold pressure adjusting the big plug isn't too bad.

One more question - if I drill a hole in the bottom plug (boost enrichment) to be able to adjust the warm pressure via allen screw --- do I need to then plug the hole I just created or just leave it open? My guess is I can leave it open.

Also to summarize - I can adjust boost enrichment by tapping in the lower plug (raising boost pressure/AFR) and this adjustment does not affect warm control pressure/AFR. However adjusting warm control pressure affects both warm AFRs AND boost enrichment pressure/AFR.

This is good info. Thanks.
Nope you can leave the plug hole open. it does not need to seal to atmosphere.

You summarized correctly. It sounds wierd but the two adjustments are not mutually inclusive.

You should try to look at a crossectional view of the internals to see how the whole mechanism works to get a better understanding of the engineering behind it.
It really is a clever device Bosch put out there.

Fred
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---"When you're racing it's life! Anything else either before or after, is just waiting"
Old 12-16-2013, 05:42 PM
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Good info on this thread thank you very much. Now that i have mounted my WUR in an easily accessible spot i can get to know these WUR's much more easily. Pushing in bottom plug with clamp slightly raises AFR's on a stock WUR ? Just making sure as i have read in other threads just the opposite.

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Old 05-07-2014, 12:31 PM
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Quote:
Originally Posted by oilonly View Post
Good info on this thread thank you very much. Now that i have mounted my WUR in an easily accessible spot i can get to know these WUR's much more easily. Pushing in bottom plug with clamp slightly raises AFR's on a stock WUR ? Just making sure as i have read in other threads just the opposite.
I haven't had a chance to adjust my boost AFR yet but I do plan on pushing in that lower plug to raise the boost AFR. I'm estimating moving the plug ~1mm to raise the AFR by 1 point or so.

Quote:
Originally Posted by Kaefer View Post

On a somewhat related note it is much MUCH easier to adjust WCP with that allen screw than it is by adjusting the plug on the top of the WUR! Live and learn...
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Old 05-07-2014, 12:42 PM
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Quote:
On a somewhat related note it is much MUCH easier to adjust WCP with that allen screw than it is by adjusting the plug on the top of the WUR! Live and learn...
Yes thank you for saving me the trouble with this thread Kaefer. I was reading other material and some people said to push the black top valve in and out to adjust WCP. Glad i spent the hours searching last night getting all the info i can. Well i don't want too much info cause then i will be wanting an adjustable WUR so i can adjust threshold AFR's also. I'll stick with 3 adjustments for now then take the next step.
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Old 05-07-2014, 12:56 PM
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Originally Posted by oilonly View Post
Yes thank you for saving me the trouble with this thread Kaefer. I was reading other material and some people said to push the black top valve in and out to adjust WCP. Glad i spent the hours searching last night getting all the info i can. Well i don't want too much info cause then i will be wanting an adjustable WUR so i can adjust threshold AFR's also. I'll stick with 3 adjustments for now then take the next step.
If you have a bone stock WUR you'll probably need to drill a hole to gain access to that allen screw to adjust WCP.

You mention wanting an adjustable WUR to adjust threshold AFRs. What do you mean by this?
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Old 05-07-2014, 01:02 PM
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Quote:
You mention wanting an adjustable WUR to adjust threshold AFRs. What do you mean by this?
A thread to read on it Kaefer.


A WUR tuning mod


Quote:
If you have a bone stock WUR you'll probably need to drill a hole to gain access to that allen screw to adjust WCP.

Yes I took apart the whole WUR to see what it is all about. Drilled a hole in the bottom brass plug plus pushed it in a bit.
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Old 05-07-2014, 03:59 PM
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great info. How do you pull the bottom brass plug back out after pushing it in? Just in case you've gone too far and need to lower afr again
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Old 05-07-2014, 05:00 PM
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Originally Posted by b5aar View Post
great info. How do you pull the bottom brass plug back out after pushing it in? Just in case you've gone too far and need to lower afr again

I'm going to have to take it apart again and send it back out a little. If i had a real adjustable WUR instead of the stock WUR that i am working with i'm sure it would be easier. I still can't figure what this poster AlanL did to his WUR to adjust it back out, picture is too fuzzy.
A WUR tuning mod
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Old 05-07-2014, 05:17 PM
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Quote:
Originally Posted by Kaefer View Post
You mention wanting an adjustable WUR to adjust threshold AFRs. What do you mean by this?
Quote:
Originally Posted by oilonly View Post
A thread to read on it Kaefer.

A WUR tuning mod
Good thread.

I guess 'threshold AFRs' is about adjusting at what boost level fuel enrichment starts?

If that is correct then I'm content with the stock threshold setting of my '87 WUR so I'll leave that alone for now. My understanding is adjusting threshold AFR is probably more critical with the early 930 WURs. The difference being fuel enrichment at boost onset (early WUR) vs. ~5 PSI or so (late WUR).
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Old 05-08-2014, 11:28 AM
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