Hissing, low power

Shizzell

Veteran Member
Joined
Aug 15, 2010
Location
US
TDI
2000 Golf 1.9L GL 2dr
Hello,

I have been investigating this hissing, or whining that occurs when accelerating. I have been noticing that I don't have as much power as I should. I collected some information regarding VCDS that may help in diagnosing:

In Engine Measuring blocks, 010: Actual MAP:
Idle: 958 mbar
2000 rpm: 989
2600 rpm: 1000

I've noticed that the Specified Map is typically 50-70mbar higher than the actual.

Are these numbers correct? I searched under the car and can't see any hoses that aren't connected or broken. Can intercoolers break in the inside where it is not observable? Any test to confirm this?

Thanks
 
Last edited:

greengeeker

Vendor
Joined
Feb 8, 2006
Location
Cambridge, MN
TDI
2002 Jetta GLS
If you had a break in your intercooler it would mark it's location with a ton of oil. Look for a split hose somewhere...again, start where you see an oily mess.
 

Shizzell

Veteran Member
Joined
Aug 15, 2010
Location
US
TDI
2000 Golf 1.9L GL 2dr
Not really any oil coming from the intercooler. All of the hoses seem in tact and tight...
 

greengeeker

Vendor
Joined
Feb 8, 2006
Location
Cambridge, MN
TDI
2002 Jetta GLS
Can you localize the hissing noise? Coming from back of engine or up by the intercooler? Maybe check your egr pipes for cracks?
 

Mavrick

Veteran Member
Joined
Feb 16, 2012
Location
Ontario
TDI
2003 VW Jetta TDI
You need to look at specified and actual boost in 3rd gear at WOT (wide open throttle). Here, you will see the computer asking for close to 2000mbar, and here you can judge if your boost is there or not. Actual boos should be within 20-30mbar of specified.

Otherwise, you need to narrow down your hissing/whining noise.. whether it is a boost leak or not.
 

Shizzell

Veteran Member
Joined
Aug 15, 2010
Location
US
TDI
2000 Golf 1.9L GL 2dr
So after I got 2 fresh tanks of diesel, performance started coming back just as I drove it. Here are the results of what it is doing right now via VCDS:





Is boost pushing more than it should? Its reaching pretty high. I should make a video of the whistling that occurs when its idling from a cold start.
 

andrewspearns

Veteran Member
Joined
Apr 1, 2008
Location
St. John's, NL
TDI
2013 Golf TDi Highline
What's the value of actual boost (in mbar) at the peak in 3rd gear? These VNT15's can handle 2440 mbar for about a second as the peak from what I've been told.
 
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