Installed yesterday a sunpro vacuum/boost gauge and the readings seems to be way different than some documention specifies. I am not sure if the gauge is faulty, or the readings are normal?? or I really do have a problem???

A4 1.8T 1997 (AEB)

At idle, the lowest value for vacuum I read with the gauge is 10 inHg. Very steady. It does not fluctuate at all. It never goes under 10inHg. Press and depress accelerator, vacuum will vary fast between 0 to 10inHg. When it returns to 10 inHg vacuum remains at 10 steady. In driving mode, it stays steady vacuum 10inHg vor regular driving.

Now the boost. 3000 rpm in 3rd gear, then accelerator fully pressed - 7psi.
2000rpm in 5th gear then accelerator fully pressed - 10 psi.

Whatever I do, boost never goes above 10 psi.

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Is it normal? Looked at some youtube videos and to what I see, they get different pattern. Is this sunpro showing different measurement scales?

According the Haynes, My vaccum is very bad. According to Bentley, I should have 1.35 to 1.75 bars at 2000 rpm => that would be out of scale of the sunpro gauge at the sunpro goes only to 20 psi boost. I believe something with bentley, since I think sunpro could not have overlook something like that..


Please, can you help with what you see in your cars?
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I have the same gauge in my 99.0 1.8tqm. Im reading about 18inHg idle when cold and 20inHg when warm. AFAIK those are the correct readings. I am only boosting to about 6-7 psi depending on what gear I am in. Idk if thats the gauge or if i have a leak.

 

You most likely have boost leak somewhere. The same happened to me, altought I haven't installed the gauge, I did my vacuum test with idle engine and realized that I had leaky hoses.

 

What happens if your turbo whistles? Is it going bad? I have a 97 A4 1.8 turbo. The part on the side of the turbo (accuator?) was bad. Ordered just that part. Mechanic installed and it was great for 3 days. Then this whistling started and it has gotten progressively louder. However, after around 60mph it stops. Any ideas?

 

QUOTE:According the Haynes, My vaccum is very bad. According to Bentley, I should have 1.35 to 1.75 bars at 2000 rpm => that would be out of scale of the sunpro gauge at the sunpro goes only to 20 psi boost. I believe something with bentley, since I think sunpro could not have overlook something like that..:QUOTE

I would pressure check the system for boost leaks. There is a procedure how to do it in the Forum tech section.

Also 1.35 bar on a stock audi? I doubt that. Also do you have the audi chipped? if chipped it would most likely be 1-1.1 bar at upper end.

On stock audi Aeb if I recall would be 6-8 psi later on the 2001 they had close to 10 psi

1.35-1.7 bar is a lot of boost for a ko3.