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Should the WUR and the cold start valve have 12v with ignition on
from my previous post you will know I am having problems with my idling.
The fuel pressure gauge kit arrived todyay, removed intercooler, checked resistance on wur and cold start valve and it was 20 and 21 respectively.
Turned on ignition and measure voltage at the WUR and Cold start valve pl,ugs and both had nothing, pushed the plate down on the cis fuelling plate, ie where the air filter sits and did not hear the pumps buzzing, I assume they should buzz
Should 12v be present at the plugs and when i pushed the plate down should the pumps not have activated.
The car starts, but struggles to hold idle after a min or two, hold it for a fee mins and its then fine, until you then switch of a restart, at this point you will see the same symptoms return
What I did notice was the cis fuel head plate, when pushed goes down slowly and returns slowly, should it not return quickly like a snapping type of action
The power supply for the WUR and fuel pumps is provided by the turbo control unit or the starter (cold start valve). The supply requires a signal from the TDC sensor or a turning starter motor.
So just switching on the ignition will provide no power, I watched a video on youtube on testing the cis system and he seemed to have power at the wur plug when switching on the ignition
The cold start valve plug also has no power to it
Where exactly is the tdc sensor located
Get yourself a workshop manual for the 911 turbo (965), chapter 25 describes the test procedure for CIS and there you will also find the target values.
thanks got it, it says to jump the relay pins 87 and 30 but also switch on the ignition, my pumps run without the ignition when i jump the relay pins 87 and 30
Meta Guru does the jumping of pins 9 and 11 send power to the wur
Managed to take a few readings today
System pressure was 91psi (6.27 bar) manual says test value should be 88.4- 98psi (6.1-6.8 bar)
Control pressure cold was 34psi (2.34 bar) manual says to check ambient temp at WUR, which was 26.5c at this temp the control pressure should be between 46- 50.7 psi (3.2-3.5 bar), so I am down 12psi on cold control pressure, what effect would this have on the running of the car and what controls the cold control pressure, is the WUR faulty.
Control pressure hot after 10 mins of running was 58psi (3.9bar) according to the manual it should be 65psi (4.5bar) so I am down 7psi.
On switching everything off the control pressure drops from 34 psi to 24 psi after 10 mins, should I be measuring the drop in the control pressure or system pressure
The only reading I have left to measure is the boost enrichment using a vacum gauge, is this done with WUR plugged in, so WUR is warm or let the WUR completely cool down and disconnected and then take the reading.
The enrichment at boost pressure is made at warm WUR, the control pressure starts to drop from of 0.3 - 0.5 bar.
At the accumulator, the drop of the control pressure is measured.
The values of the WUR deviate with my car similarly and there are no problems with it. Tendentiell runs the somewhat too rich, but this is not tragic. Anyway, I do not think that replacing the WUR will solve your problems.
Try tightening the intake manifold nuts. There are 12 in total and with the air mass sensor installed not all are accessible but the point is to get a feeling for whether some are loosend or not.
I will have a look at boost enrichment and check both pumps are running and have 12v
I seem t have some saying its the WUR others saying not, what else could it be if not WUR or intake manifold nuts.
If it was intake surely it would not drive fine as after a few mins of starting all seems well, until i switch off again, regardless of warm or cold, the idle is low again for a few mins, need to hold it a few mins with the throttle, the co was also slightly hi on idle
Control pressure cold was 34psi (2.34 bar) manual says to check ambient temp at WUR, which was 26.5c at this temp the control pressure should be between 46- 50.7 psi (3.2-3.5 bar), so I am down 12psi on cold control pressure, what effect would this have on the running of the car and what controls the cold control pressure, is the WUR faulty.
Control pressure hot after 10 mins of running was 58psi (3.9bar) according to the manual it should be 65psi (4.5bar) so I am down 7psi..
So, your wur is out of spec, biased to rich. You can get your wur fixed. I recommend you do that as you don't need to check boost control pressure.
I took my car on a trip yesterday and was reminded of the fact that the wur is a imperfect, imprecise device. In hot weather, the wur will get heat soaked if you shut the car off and let it sit a while. The bi-metallic spring inside the wur gets affected just like the cold to hot cycle, except it's from it's hot position and therefore will lean out the idle mixture. AFR climbs from 14.7 to as high as 16.0, which drops your idle speed. Fortunately, the engine won't be damaged when this happens because it's running at no load (this is a emissions and economy strategy on all modern engines;run lean under idle/no load conditions). The minute you press the throttle, afr's return to normal and cool fuel going through the wur returns it's performance to near normal.
The solution is getting the wur rebuilt including a new bi-metallic spring.
My other question is are you able to adjust idle speed with the idle speed screw? If you can then I don't think you have an air leak.
Last edited by Metal Guru; 07-17-2022 at 08:48 AM.
If its defintiely the WUR then I can buy a new one, I have also emailed Brian regarding the adjustable WUR and his rpm csv kit, Has anyone fitted this to their 964 turbo, Is the rpm csv kit difficult to fit
When the WUR is rebuilt is a new bi metallic spring fitted
Not sure if Brian would be willing to send to the uk
I have not attempted to adjust the idle could give it a go, if a recall it is the large screw on the side of the throttle body
Checking boost enrichment, can someone please confirm I am doing this correctly dont want to damage the WUR diaphragm
I have a vacum gauge, is it vacum I am pulling as mannual says 0.5 bar positive pressure, if so is 0.5 bar 15 inHg mm on my gauge from pic below.
If its defintiely the WUR then I can buy a new one, I have also emailed Brian regarding the adjustable WUR and his rpm csv kit, Has anyone fitted this to their 964 turbo, Is the rpm csv kit difficult to fit
When the WUR is rebuilt is a new bi metallic spring fitted
Not sure if Brian would be willing to send to the uk
I have not attempted to adjust the idle could give it a go, if a recall it is the large screw on the side of the throttle body
Dude, the data is screaming at you that the wur is an issue.
You don't need to buy a new wur.
Check out these guys www.cisflowtech.com
This is who Brian (Rarlyl8) and a lot of other people use for CIS service. You could work through Brian or Larry at Flowtech.
If you intend to keep your engine stock, stay with a stock wur.
Last edited by Metal Guru; 07-17-2022 at 12:39 PM.
07-15-2022, 08:59 AM
Should the WUR and the cold start valve have 12v with ignition on
