wur 0438140089

[log40]

Hello, excuse my English , I'm French. I'm looking for a wur 089 internal schematic where i could see the way and the action of the vacuum on the regulator.I have one schematic of the wur model before the 089 which have only one vacuum outlet linked to the thermo valve, i understood the vacuum lean the mixture at idle and part load and enrich the mixture at full load by lower the regulator membrane. In this case the vacuum outlet is on the top of the wur and the lower chamber is linked to the atmosphere , so the vacuum in the upper chamber tend to lift the regulator membrane and lean the mixture. In the case of the 089, the vacuum from air intake is linked to the wur bottom outlet and the air filter vacuum is linked to the top of the wur. If the internal schematic is the same, the action should be reverse and i should not understand this logic. The trouble is that i have note during the tuning of my AFR the mixture was richer with the vacuum hose from thermo valve (air intake) connected and leaner when disconnected (conditions idle and warm engine). If someone can help me about that, thank for advance.

[boyt911sc]

Originally Posted by log40

Hello, excuse my English , I'm French. I'm looking for a wur 089 internal schematic where i could see the way and the action of the vacuum on the regulator.I have one schematic of the wur model before the 089 which have only one vacuum outlet linked to the thermo valve, i understood the vacuum lean the mixture at idle and part load and enrich the mixture at full load by lower the regulator membrane. In this case the vacuum outlet is on the top of the wur and the lower chamber is linked to the atmosphere , so the vacuum in the upper chamber tend to lift the regulator membrane and lean the mixture. In the case of the 089, the vacuum from air intake is linked to the wur bottom outlet and the air filter vacuum is linked to the top of the wur. If the internal schematic is the same, the action should be reverse and i should not understand this logic. The trouble is that i have note during the tuning of my AFR the mixture was richer with the vacuum hose from thermo valve (air intake) connected and leaner when disconnected (conditions idle and warm engine). If someone can help me about that, thank for advance.

Log40,

WUR-045 / 069 / 089 all have similar configuration except for the values of the heating element (Ohms). The top is connected to atmosphere and the side port is connected to vacuum via the thermo valve. What is year is your car/engine? US or RoW?

Tony

[Vereeken]

I am no sketch artist but I am sure it will do. 089 is the number of the beast WUR wise ;o)

Do not forget the vac when adjusting cold control pressure....

The key to good vac connection is to make sure you do not swap around the connections front/back and/or below/above throttle house.

[Vereeken]

Oh btw the above only applies with ROW non US car with a 089 WUR.
I have seen my drawing popping up on other SC sites so there must be some truth in it

But since you are French fat chance it is ROW.

If I read your last sentence you have most likely swapped around 1 and 2.

Also possible is that you have connected 4 to a vac source and now 2 and 4 act against each other.
4 is nothing more than a vent to atmosphere. Some say it is to compensate for high altitude driving but I ain't that schmart to understand that.

2 leans out the mixture. If you disconnect 2 and plug the line your mixture should shoot up (and your AFR should go to the 12.X)

I also believe (but not tested) that at WOT the vac falls away on 2 thus further enrichening the mixture. Makes sense but never measured it.

[log40]

Hello, thank you for your quick responses. My car is sc 1981 ROW.
All my vacuum connections are same as your drawing which is same as the drawing from Porsche manual I use. No doubt I have checked and rechecked. I have vacuum on 2, Atmo on 4 and Atmo on 1 (idle).
Today I have checked the air additional valve and the deceleration valve, i had already checked the thermo valve and air additional regulator, all are OK.
i made these other tests today:
disconnect 2 --> idle increase 300rpm
disconnect 4 --> no change idle
disconnect 1 --> no change idle

last time I did the test with my Guson gastester, (pretested on my twingo co 0.5).
First i tuned my engine to 1,5-1,7 co and when i tested the car i realize it was too lean.
I disconnected 2 and i realize the co drop. So i decide to retune whith 2 disconnected (when connected i had 1 co point more).After that i reconnected 2 and tested the car. it was running very well.Only the idle is not perfect.
So i don't understand why i 'm richer when connected to vac.
I do not have the pressure tester, so I can't investigate further. But there something no clear with the shematic of the wur i have and the 089 characteristics. Let me find this schematic i will explain.

[log40]

This is from Bosch K-jetronic book 1. They don't mention the ref of the wur, only is Wur with vacuum commande.

[log40]

If the wur089 has the same schematic, it should have a reverse action (but non sense cause no enrichment by thermo valve). See the corrections in red. For me the wur 089 is different inside.

[Reiver]

the 089 is different as the wur controls enrichment thru vacuum as a function.
US cars use the lambda.