Hello i need some help with my A4 B7 2006 Elite.


This is a weird Failure since the car Works Wonderful as it is Cold.

Acceleration is Awesome and power kicks your head back as you step on it.


But as the car warms up, power goes away...

Engine is 2.0T FSI 200 HP With 31,500 miles on it

Diverter Valve has already been replaced with the new upgraded one even the old one is in perfect shape (it only feels like the spring is old and lost hardness), no holes on the red latex. It had a related code aiming to the diverter valve already erased and not returning.

I had a coil pack replaced and switched positions of them already
Spark Plugs Replaced
Oil also Changed 100 miles ago
Air Filter replaced New
Gas Filter replaced New
Egine is in perfect IDLE and only seems to fail as you remove the oil filler cap or dip stick

No signs of PCV failure (no oil on coil packs or spark plugs)
No TCM Codes

Same failure prevales, reading this codes on the Scanner

00665/ 16683 /P0299 Boost Pressure Regulation: Control Range Not Reached

01287/P0507/16891 Idle Control System RPM: Higher Than Expected

I noticed this like dust and oil in one of the Hoses going from the Engine to the intercooler passing under the Right Head Light.

The car feels like some valve is fixed on one position and all power is going thru there, the car sitll accelerate, but really slower than when it is cold.

Other thing i noticed is that all hoses feel like weak and lose whe the car is hot

Should i Replace all hoses i order to make shure they can take the heat and high pressure?

Or Where should i look for this leak?

This turbo has some kind of spring actuated valve on it that could remain open leaving boost to escape?

Or is there a known valve that gets stuck or blocked that should be replaced?


I did the leaking test by removing the hose that ends up in the maf sensor and injecting air in to it.

No leak apparently found, but if the valve works fine when cold it should fail under boost and remain open only until it cools down again.

I really need help since this has become a pain, a real pain, because there is no power when needed.....

 

To me it sounds like a leak. ANy time we had boost issues on cars, 90% time of the time it was a leak in the system.

Aluminum parts under heat expand. I'm sure your aware of this. It seems you have been trying to diagnose this and have done leak tests. Did some research and couldn't find too much, but many have said that o rings need to be replaced from the stock ones and silicone to be added.

A wonder if the heat is faulting the blow off valve that recirulates the pressure back into the system. It is stock correct and you havn't put any after market parts on?

Another thing to do is make sure your using a good oil that can handle the heat of a turbo. Types of oil is crucial and using a thinner oil can cause the turbo under heavy load to stop performing correctly.

Looking around, I found that someone was having a boost issue with a quick drop under load, this was a result in the plumbing having a leak on the intercooler. Fix was removing o ring, siliconing and replacing with a new o ring..

I'll let ya know if I find anything else.

 

Welcome to the pains of turbocharged cars

Did the car do this with the old DV? Have you replaced anything else in the vacuum/pressure system recently? If you want to diagnose this yourself, you're going to need some tools: vacuum tester, pressure tester, and preferably VAG-COM. Do the following:

- Test your vacuum system and your charge-air system and see if it's leaking.
- N75 test via VAG-COM
- Use VAG-COM to run logs - N75 duty vs requested boost and engine load; MAF vs RPM and requested boost; etc.
- Try unplugging your MAF and see if the problem goes away.

 

Thank you

But not exactly a newbie to turbo issues ahd yes, headaches..


I had this 2004 A4 1.8T with similar problem 6 months ago.

The vacuum system in 1.8T engine seems a bit simpler and easier to fix these problems since check valves where every where and also hoses easier to locate.

In ths one the turbo is like hiden and lots of tiny hoses everywhere, not counting the Diverter valve integrated to the turbo.

This is making a nightmare to find this weird leak.

Im pointing to a valve failure because of the hot-cold behavior and it is an internal i guess..

Any one has a diagram i could use of this turbo, to have an idea for finding this leak?

Any thoughts?

 

Good to hear that you have experience - as you know, tackling vacuum/boost issues can be very frustrating! There's been more than a few times, when I almost swore off turbo cars and bought an N/A one

Google will turn up the vacuum/charge-air diagrams. If you run the VAG-COM logs, they can help guide you to the source of the problems, failing that it's just legwork. Do you know anyone that you can swap N75/N249/etc. with? That would be a big help!