20V TURBO LACK OF POWER

[eyanjohnson]

Hi I have a 2003 mk4 golf gti 1.8t 20v and have lost power. Can anyone help me?? I have no warning lights on the dash. The car runs ok but doesnt pick up like it used to (feels like a natrualy aspirated 2.0l woulf feel like) Turbo feels ok. Can hear whistle and actuator seems to move. Has anyone had the same problem?? possible air mass problem?? Thanks.

[RTechUK]

LOL.

Welcome to the club m8,

You need vagcom to log the requested and actual boost to see whats going on.
Here is a fault guide http://www.r-techpower.co.uk/forum/viewtopic.php?f=38&t=47

Channel 115: Requested Boost and Actual Boost

This is a very helpful channel for diagnosing boost leaks, trying to figure out why your car went into limp mode, and seeing if the software or hardware (electronic or manual boost controllers) are doing what they should be. This channel displays the boost requested by the computer (requested boost) in the first column and the boost actually made by the turbo (actual boost) in the second column. The readings you will see here can be misleading. First, you should know that the numbers you will see are not yet corrected for atmospheric pressure (about 1040mbar at sea level). The atmospheric pressure seen at the boost sensor is tough to estimate with complete precision, but I have found that subtracting 1000mbar from the numbers gets you close enough to actual boost unless you are living at 20,000 feet above sea level. The next thing you have probably noticed about these numbers are that they are displayed in mbar instead of psi like we are all used to. Well, this won't be a problem thanks to the metric system. 1000mbar = 1 bar and 1 bar = 14.5psi. There you have it.

So, can we all figure out what boost level in psi this car is requesting and making at 3000rpm?

RPM Requested Boost Actual Boost
2500...2100...1800
2750...2200...1950
3000...2200...2250
3250...2200...2200
3500...2200...2100

The correct answer is:

The computer is requesting 1.2 bar of boost at 3000rpm. This can also be expressed as 17.4psi.

The turbo is boosting 1.25 bar of boost at 3000rpm. This can also be expressed as 18.1psi.

[ToddyGTi]

sounds like your Air Mass Sensor has died mate. They don't throw warning lights up when they die either.

[eyanjohnson]

cheers for the advice chaps ill tet you know how it goes. Was on my way for a ECU re-map when it happened... how ironic :-)

[turbomike]

hi mate does ur car boost of is it totally flat iv fitted fmic and lost all power since