Performance problem, like it has 200hp under the hood...

[C-24]

Everybody says my S4 is fast, I laugh at them because being powerful in acceleration and entering fast in corners is not the same. I am getting p*ssed off with my S4 (I also love it).

I don't know how you call this part in english, but the "hose" that comes after one of the turbos was broken, so all the pressure of the turbo was coming out of the car and therefore power was miserable.
I replaced it with a new one and the car is going only slightly better (and I don't hear the turbos as much as before now that the air is kept inside of the hoses).
But... this is not how it used to be! I remember the car had excellent acceleration, loads of torque (on paper it has 320hp and 500nm), but now it's SLOW after 60mph or 100kph... I thought that maybe I'm used to the car so it feels slower, so I tried it on a german autobahn, the top speed was 230kph at about 5k rpms or 5'200rpm. I had the feeling that if I'd put 80% of the gas pedal the car would go a little faster than 230kph, like if something is obstructing the performance while doing WOT.

Is it in limp mode ? Why ? I disconnected the MAF to see if it would improve anything, but it didn't.

Please help, I have this car for 4years and managed to enjoy it during only one year.

[Blue_Thunder]

Sounds like you have another boost leak. I would check the TBB.

Where you have mentioned it feels quicker on part throttle, this could be because at part throttle the car can hold a little boost, but once you request full boost the extra pressure is escaping out a hole.

Do you have access to a pressure testing kit?

[C-24]

First, thank you for your reply!

My friend mechanic did only notice that hose, I don't know to which turbo it is related, the left one I think. Maybe he thought that it's the only broken part.

About the pressure testing kit, I don't know, my friend should have one, I guess...
TBB ? Is it something about the throttle body ?
I can connect my notebook to the car via the obd, maybe I can see some results frome there ?

[Blue_Thunder]

Yes, the TBB is the rubber pipe which connects the charge pipes to the throttle body.

Vagcom will most likely have some fault codes stored.

[C-24]

Since I hear no air going "out" of the hoses I'm not sure if there's still a problem with the TBB or an other hose. I will check it tomorrow. Thanks you!

[bobbler]

Could also have EGT faults logged that need fixing/clearing, that can reduce power considerably I found.
The TBB broken also it is hard to hear it with doing a pressure test, certainly nothing I heard when mine had a very small tear in it but again affected the power output noticeably.

[Dippy]

VAGCOM & boost guage are 2 essential tools for every S4 owner...

[C-24]

I did a diagnose today, the car has a fault that I can not reset.
It's in german : "Fehlerlampe für elektr. gasbetätigung-K132 elektr. fehler im stromkreis"
This has something to do with the gas-pedal electrical signal. I searched on the net and I'm not sure but it may be related to the EPC, electronic power control.
Do you know which fault is this ? What may I do to reset/repair it ?

edit : in english it is "Drive by Wire-MIL (K132), Circuit Electrical Malfunction"

[MilkybarKid]

throttle body wiring? would explain the crap power?

[Dippy]

That DTC does not give much idea of the failure mode. The DBW system has 2 potentiometers on the accelarator pedal and the ECU uses the signals from both of these to determine it's exact position. Then it can control the throttle flap using a servo after deciding what air flow rate should be controlled.

So there are two parts to the DBW circuit (as opposed to the ECU itself which has to be considered a black box): The input from the two pedal pots; and the output to the throttle servo.

The throttle servo has a self-calibration mode process called Throttle Body Adation. You can invoke it from VAG-COM, but the car also does it itself. If you turn on the power but do NOT start the engine and do NOT touch the accelerator pedal for about 2 minutes, it will do a TBA (you will hear the servo operating).

If that does not help then it should be a problem on the input side. It would be good to monitor the pot readings as the pedal is depressed.

[C-24]

Hey Dippy thank you!

To start a TBA I should just turn the key "on" but not that far to turn the engine on ?

I bought another pedal, new one, because the mechanic thought that maybe the electronic was damaged due to humidity. I think the car is going better but really not that much.
I looked for S4 stage 1 on youtube, and it seems mine has same acceleration, but the top speed is really slow... still 240kph (150mph). To attain 180kph (110mph) in 6th is quick but more than 200kph (120mph) becomes hard for the car. I noticed that when I press 80% of the gas pedal at 220kph (135mph) the car accelerates quicker to 240 than with wide open throttle. I think it is the same for the acceleration in 2nd or 3rd.

It's such a nice car, but I am going to sell it soon and I need to fix all those things, so all the help I get can is really handy. thanks!