911 2

Has anyone rebuilt their WUR (Warm Up Regulator) and added a bolt to adjust the mixture, im assuming once rebuilt the pressures are set at idle only
Does the WUR just control the idle fuel mixture or does IT also it control the fuel mixtures when driving and on boost, I ask, as when rebuilding, the pressures are set by the screw in the WUR, not a problem on idle as the worst case scenario is the car stalls if the adjustment is slightly out, but do not want a weak mixture on boost as thats a recipe to melted pistons.

Black_Hat

Don't experiment and grenade your engine

the WUR controls all , Cold pressure, warm pressure , boost enrichment

send the WUR to https://www.rarelyl8.com

Stefan

911 2

yes definitely will not experiment, you are correct, incorrect fuel pressures and goodbye to the engine.
I have the cis gauges and the manual settings to adjust the wur, just not sure if the settings are done per manual and therefore will the on boost settings automatically be correct or is further adjustment needed on the dyno, they are not difficult to rebuild at all

peterpullin

there is a smal risk to change settings. i did some times. the mean problem is not changing mixture (without wanting to do so).
you can not make our wur fully adjustable without damage one of the funktions for ever. one of the setting points is reachable from below. you have to drill through the altitute correction to reach it from outside.

so better let it do a specialist...

fritz k.

The designation WUR is misleading because the mixture is not only regulated directly after the cold start (warming up) but also over the entire operating range including boost. For the boost range from 0.3 bar on control pressure will be reduced up to 1.1 bar. Therefor the wur has a second membrane that can be adjusted within limits.

When the control pressure of the WUR is out of specification, the cause is almost always the spring that pushes the plunger against the stainless steel diaphragm at the fuel inlet. The decreasing spring pressure can be compensated by placing 0.1 -0.4 mm washers underneath.

I don't think the solution with the adjusting bolt makes sense because it only has an effect on the warm-up control. Once the bimetal is completly regulated its position has no longer any influence on the spring pressure/control pressure.

If the system and control pressure are within specification you can be relatively sure that the mixture is ok. when experimenting at least an afr logger should be in the game.

There are repair kits available for overhauling the WUR, e.g. from
https://www.tstechnik-shop.de/shop/k...paratursaetze/

911 2

I opened my WUR today, it is a little more complex than your standard wur as it has a second metallic strip at the bottom, the bottom section of the wur already has a threaded section where an adjustment can be made
My control pres was 34psi at ambient it should have been between 46 to 50.7 psi control pressure hot was 58psi manual states it should be 65psi
Are you saying best not put in a bolt for adjusting the pressure

911 2

bottom of wur with adjustment port

peterpullin

onnyour last picture you see the brass bellow. this is the altitute correction. the last but one picture shows the hex screw you need to adjust if you want to make it full adjustable. so you had to drill through bellows. not an goodd idea!

fritz k.

Yes, your WUR is customized, it has a second bimetal and an adjustment option in the lower part. I can't judge whether that makes sense because it's not exactly clear how it works.

The values ​​​​of your WUR tend towards a rich mixture, which is better than a mixture that is too lean if there are at least small deviations.

And yes, I don't believe in the method of moving the abutment of the bimetal with a bolt. I would put a 0.2 or 0.3 mm thick washer under the upper small spring, which presses the stamp against the stainless steel membrane, so that the original spring force should be restored. This changes the control pressure over the entire effective range.

The lower membrane is responsible for the full load enrichment. The allen grub screw in the middle changes the preload of the large spring and the control pressure reduction at boost can be adjusted.

Fritz

911 2

is my WUR not a standard 964 turbo item
just waiting on some instructions and will finally rebuild and see how it goes
if it is running rich then this probably explains why it would stall and then not restart unless I waited a few minutes
On striping down all seems fine but the metal thin circular disc found in the top section of the wur had surface rust on it, peculiar as the item is made from stainless steel

peterpullin

this is a standard unit for our cars. no modified unit. this last single turbos (from 1988 on apx) had this or similar mounted.
i repaired some so i know this is factory.

if your car does not start in warm condition it is NOT the wur. accumulator or weak pump (one of two) is the first route.

911 2

it starts fine but it sometimes will not hold the revs when it gets warm and if it stalls when warm i twill struggle to start unless I wait approx 30 seconds, accumulator is a new bosch item, when this was replaced the car started much better

peterpullin

try the valve at the fuelpump (front). may be it holds not the backflow as it should.

911 2

where exactly is the valve located, are you referring to the one way valve on the pump outlet, if so how do I test it

peterpullin

hello back,
yes at the fuel pump. front one. no test i know. it is not expensive.

you should follow diagnostics step by step.

first step is testing pressure. cold, warm, how long does your fuel pressure hold a rest.
then (if faults are found) you have to start one step by the other.

in your case i would look at the injectors. how do they flow and do they dripp after shut down.
for me your problem is more fuel head than other issues.