Hi guys
i have 02 b5 s4 with automatic transmission, which i tunned with giac chip incl DVs..
some time ago i decided to open the engine since i had some problem with the piston(which was changed), and at the same time i changed my turbos, cause old ones was burn and was leakin.. so after the engine was back again in car, i started to have different problems like:
1. at morning start-ups tachometer starts to go down(dragin between 700-400) with engine makin pow- pow noises.. when it warms a bit.. everything goes back to normal..
2. car has no torgue as it used to be it can start as a rocket on cold engine, but after 4.000(on first transmition) on tachometr it slows the acceleration.. and overall acceleration is not stable at all.. and u can feel collapses in acceleration ..

i was tryin all my best to find out what is goin wrong, but i dont have S cars service in my country.. i brought it from nyc..
it also feels like it pumps much more fuel into engine that it can burn ..
if u have some advises for me, it would be very much appreciated.. what i can start with checkin .. i think ill order intake pressure tester to check the air system.. is there any other way to check where the air is leakin from? maybe it has to do with some sensors?
thanks in advace
sorry for my bad english, not my mother tongue

 

forgot to mention about some mistakes showin on VAG.. - missfire in left or right banks .. check engine is always ON..

 

check spark plug gapping first, then move on to coilpaks, then to o2 sensors. you seem like you know cars so its plain to see its something stupid killing you. oh yeah also check maf, the o2 sensors and the maf you will need a multimeter or vag com and will have to read the voltage levels to see if there in spec. also it might not hurt to reset the tb.

 

If you don't have one, purchase a VAG-Com.
Then read all the codes & let us know what they say.

misfires are usually plug related, or fuel.
The coil amps might not be connected, or working properly. These are the plugs on top
of the airbox. Also you might have a bad coil, or plug.

The fuel could be due to the FPR not working, or a bad vacuum line.

There can also be a problem with you turbo wastegates. They may need to be adjusted.

Since this is all speculation, get the vag, read the coeds, then do some logging. With Vag logs, we can
track down at least what system is causing most of the problems, and work from there.

 

Hello guys, Thank you very much for such kind interest in helping me get my babe back on road! As u told me to get the vag check, I went straight to audi service and got 6 mistakes shown on the monitor.. here they are:
16805 warm up catalyst efficiency (bank 1) below limit (P0421)
16815 warm up catalyst efficiency (bank 2) below limit (P0431)
This has to do with my catalysts.. well basically, I don’t have them at all.. I cut them of, putting inside some resonator to have more power.. since emission is not a big deal in my country.. so don’t take these mistakes into account, since car performance did not change at all when I cut them. The reason I did cut them: cause some jerk technician told me that my problem was in cats.. and cutting will get my car back to normal.
Other mistakes:
17539 P1131 - Oxygen (Lambda) Sensor; B2 S1: Internal Resistance too High
16538 P0154 - O2 Sensor Circuit - No Activity Detected (Bank 2 Sensor 1) A
16826 P0442 - Evaporative Emission Control System - Leak Detected (small leak) B
17965 P1557 - Charge Pressure Contr. Positive Deviation

So here they are.. if there is problem with this O2 sensor.. can u tell me where should I look for it? Where is it located? Is it possible that car lost so much torque because of this sensor? Maybe technicians didn’t connect it.. maybe its not working at all…. Any other suggestions on those mistakes? What do u guys think of Giac software? Maybe I have to reprogram the ECU again? Can software change itself, or be corrupted after sometime? thanks for helpin guys!

 

Judging from the codes, I'd say that the o2 sensor needs replaced to start with. Probably most of the rough running problem. After fixing that I'd check for boost leaks with a evap smoke machine or homemade boost leak tester.

 

As devil said it looks like you have a bad o2 on the driver side primary o2. Change that first
Second is the EVAP is leaking or not hooked up right look into that
Third the charge pressure. You either have a boost leak or the car is over boosting

I would get some new 02's and a pressure tester and look over the car. These codes will set a CEL and make the car run poorly. Due to the positive charge the car can go into limp mode