svenson69

how do I know that? Please advise.

What else do you need? Can you give me your email so that I can send you the entire excel files?

Thanks

RolledMySTi

Do you have a boost gauge?

Also, while you can do logs with vag com they are very basic and should only be done monitoring one or two things at a time. For the big detailed logs you see people use ecux. You can get ecux from ecstuning.com. I am waiting to get mine currently so I can learn how to make proper logs.

svenson69

i will check my boost gauge and get back to you

svenson69

my vacuum at idle is at 15 or (-15)

What does this mean anyway?

donromani

Vacuum is measured in In Hg as opposed to PSI for positive boost. The vacuum reading indicates the relative pressure difference between the pressurized (turbo) side of the engine and the non pressurized side. At idle your throttle is fully closed, so pressurized air is not allowed into the combustion chamber. The turbos are still spinning and making a marginal amount of boost, causing pressure to build up on one side of the throttle.

The s4 engine is configured to create a certain amount of vacuum at idle - if your car is unable to hold a vacuum then the system is improperly sealed somewhere, allowing pressurized air to escape.

RolledMySTi

Was that reading at start up or once the car is warmed up? You should check the reading when the car is fully warmed up. If that is what you did it means you have a boost leak. You should be between 20-22hg at idle when the car is warm.

The first thing I would is take out your throttle body boot and check it for any damage. If you have an 00 or 01 check your f-hose as well. If those are both ok you need to pressure test. If you are not sure what that is or how to make it check this page out.

http://www.awe-tuning.com/pages/shar...ssure%20tester

svenson69

Thanks, I checked the vacuum after about 15 minutes of driving. At idle it is between 22 and 23 hg.

My throttle body boot is new OEM one and my f-hose the same. I changed them because of a leak. I have tested the car up to 25PSI with an air compressor and no leaks. I had a leak in the TBB, but that is fixed now.

Whats next?

Thanks to all

RolledMySTi

If the car pressure tests ok and the vacuum is in the 20's I would say you don't have a vacuum leak. This is where having a vag com to pull codes would really help. Is there an Audi dealer or any shop that can pull codes for you?

svenson69

Thanks, can you give me your email so that I can send you the logs that I made?