# 4759 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)



## 2006b5 (Jul 27, 2010)

Hello. I am trying out my new VAG-COM on my 2006 Passat 2.0T and I am looking for guidance. The car has developed a rough idle, like surging. It is somewhat smooth for the first minute after cold start-up but then gets really rough. I installed a new "D" style diverter valve but that made no difference. Here is the fault display from the VAG-COM:


VCDS Version: Release 10.6.0

Address 01: Engine Labels: 06F-907-115-AXX.lbl
Control Module Part Number: 3C0 907 115 F HW: 3C0 907 115 F
Component and/or Version: 2.0l R4/4V TFSI 0030
Software Coding: 0404010A19070160
Work Shop Code: WSC 24219 444 84580
VCID: 234F001C9BBD
1 Fault Found:

004759 - Pressure Drop between Turbo and Throttle Valve (check D.V.!) 
P1297 - 001 - Upper Limit Exceeded
Freeze Frame:
Fault Status: 01100001
Fault Priority: 0
Fault Frequency: 1
Mileage: 124343 km
Time Indication: 0
Date: 2010.08.11
Time: 18:40:45

Freeze Frame:
RPM: 2172 /min
Load: 20.4 %
Speed: 0.0 km/h
Temperature: 57.0°C
Temperature: 27.0°C
Absolute Pres.: 980.0 mbar
Voltage: 14.224 V


Readiness: 0110 0101

Does anybody know how to check for pressures at turbo and throttle body? Or how to test if DV is being opened by the ECU? Any tips would be appreciated. Thanks.


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## [email protected] (Jul 19, 2010)

http://wiki.ross-tech.com/wiki/index.php/17705/P1297/004759

Double check your pressure pipes (boost hoses) and be sure there is no place for leaks to happen. 

I think an output test would operate the D.V., but not 100% sure.

Also take a look at 01-08-115 when you have a helper watching the computer, see if the actual boost is pretty much the same as the specified. Using the graphing feature of VCDS makes this easier to check. If the actual boost reading is not closely following the specified, it would imply a boost leak.


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## Dana @ Ross-Tech (Sep 15, 2009)

In addition to Jef's suggestions, also see the TSB reference here: 17705/P1297/004759 - Pressure Drop between Turbo and Throttle Valve

Pull the oil cap off at idle and see if it's sucked on. You might want to call the local VW dealer to see if this breather valve was a recall on your car.


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## 2006b5 (Jul 27, 2010)

*Pressure drop update*

Wow, two good tips already. They both have merit, yet I am still digging. I wanted to get this post out before the end of the work day. I checked the pressure pipes and the intercooler and it all looks good. When I monitored 1-08-115 I found the boost pressure specified started at about 850 mBar while boost pressure actual was at about 1070 mBar. After running for about a minute the BPS started dropping and was down to 450 mBar and the BPA stayed up in the 1000 mBar range. The more the BPS dropped the worse it ran. I need to learn how to capture this measuing block pane and graph so I can put it in my post. I'll work on that but I wanted to get this update back out right away.

The other tip about the pcv issue and vacuum through the filler cap. I pulled the filler cap off while it was rough idling and there is distinct vacuum, pulsating. You can feel the pull and hear it, but unfortunately I am not familiar with this on a properly running engine. This car is new to me. I am going back out to the car to see if I can get this data logged, I'm sure you would like to see the graph. Thanks again...


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## 2006b5 (Jul 27, 2010)

Dana,
I have a question in regards to the TSB link shown here. The second and third line under possible causes mention a Boost Pressure Control Valve (N249) and a diverter valve. Aren't these both the same valve that is located on the side of the turbo body? P/N 06F 145 710 G. I have a diagram of it where it is also called a turbocharger recirculating valve. Is there another valve that I am missing other than N249?


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## 2006b5 (Jul 27, 2010)

It was the breather valve (PCV). I took the line off between the pcv and the intake and plugged the intake and now it idles smooth again. Now I just need to fix/replace the PCV. Thanks Jef and Dana.


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