fambino

So i got my ECU reflashed and my car tuned last week...

There is no check engine light and the Audi computer is reporting no codes. Everything was fine until a few days ago... Whenever I press very lightly on the gas pedal when accelerating, there is no problem... but as soon as I try to giv'er, it feels like I don't have much power and whenever my car typically kicks in, instead, I hear a shitload of air escaping but I have no idea what it may be.

My mechanic suggested the Mass Air Flow, while a buddy of mine that's a mechanic at Audi said to check the intake valves.

HELP, anyone ??

fambino

So i got my ECU reflashed and my car tuned last week... (as per the post 2001 S4 CHIPPING - thanks to those who helped).

There is no check engine light and the Audi computer is reporting no codes. Everything was fine until a few days ago... Whenever I press very lightly on the gas pedal when accelerating, there is no problem... but as soon as I try to giv'er, it feels like I don't have much power and whenever my car typically kicks in, instead, I hear a shitload of air escaping but I have no idea what it may be.

My mechanic suggested the Mass Air Flow, while a buddy of mine that's a mechanic at Audi said to check the intake valves.

HELP, anyone ??

mikeh

The problem sounds like the throttle body boot may have a leak. My son's car had the same problem and it is easy to find and fix.

Remove the air cleaner assembly. Go to Home debot and get a 3" ABS 90 Elbow and a 3" Fernco fitting, and a 3" end cap. ON one end of the 90 elbow put on the fernco fitting and end cap. On the end cap drill and tap two fittings one for a gauge and one for a Schrader valve.

Attatch this new tool to your intake. Using an air compressor pump up no more than 15 PSI and run it through your new tool. Then listen for where the air is leaking and in most cases it will be the throttle body boot.

You are suffering from turbo leak and this will find where the leak is coming from. Then replace the appropriate hose.

If you are having trouble understanding or following this PM and I will take pictures of the tool my son made to find the problem.

K04-S4

Fully Agree with Mikeh

The description suggests an intake boost pressure leak. The most common issue is the stock Throttle Body Boot develops a tear. The TBB likes to tear under the clamps making it difficult to visually find without performing a pressure test. More rare but a hose may pop off a connection point for example at an intercooler. A pressure test usually reveals a large leak easily with as little as 5psi applied, small leaks may need a bit more pressure to find but personally I've never had to go past 10psi to find any leaks.

mikeh

We have PMed each other several times now to the following conclusion. I don't know for sure if its the throttle body boot or something else, I have not seen, heard or experienced the car. I agree with KO4 that a visual will most likely not find the leak which in my son's case was under the clamp and your mechanic should have known this before making a positive conclusion ruling out the TBB. Since I am not a mechanic I am suggesting that it really is a process of elimination and checking for leaks in the TBB or other hoses is a cheap elimination process before going to the next step.

I hope this helps!! I will post up the pics of the specialty tool my son made up to find the leaks in the system. This will be posted up along with some description in the DIY section (if its not already there) for everyones benefit.

K04-S4

http://www.awe-tuning.com/media/pdf/...ure_tester.pdf

Instead of a straight through air coupler, I put a valve on the one I made to permit gentle application of air pressure. Recommend start with regulated 5 psi. If you accidently connect full line pressure you will likely damage Turbo oil seals etc.

This test needs to be completed to find and confirm location of intake leak(s) for the 2.7T.

mikeh

KO4-S4.....thanks!!

This is almost exactly what my son made up except we used a 90 deg angle for better access and attached a valve and gauge to positively see the pressures. Totally agree with starting off in 5 psi increments.

fambino

thanks gents, i appreciate your help and effort.

my mechanic was aware that a visual inspection wasn't 'enough' we just didn't have time for more. he did say that although it could be the TBB, it sounds like the mass air flow but he wasn't sure... I'm going to see him Thursday to check both the TBB and diverter valves.

i'll def try to do the TBB at home tonight by replicating the contraption posted.

thanks again ! can't wait to rip it up in my S4.

sakimano

weird. could be a vacuum leak, but for it to be loud like that...may be an exhaust leak. Both can cause a strange hesitation. Your MAF should be pretty easy to check...but you'd have all kinds of codes for any of the problems mentioned by the experts you spoke to. Any of them check the car out?

p.s. who tuned the car???

fambino

thanks to those who replied, i do appreciate it.

here is the update:

turns out that both my bypass valves and my TBB were ****ed. One valve was leaking, the other was completely blown, and my TBB had a few rips in her... All were changed, i put in some 710N valves and she's driving great again. Perhaps garages should sell these as a combo pack, it would be a smart marketing move from what I hear.

I did have one turbo slightly surging due to the leaky valve. It soundes like that got fixed but, at cold startup (or at least until my car is compeltely warmed up), i still hear something weird going on with my turbo... i'll just deal with it when it blows, i think, considering a turbo job is 17 hours (as quoted by Tapp Auto).