Hello Everyone,
First post and I come seeking help on my tuning journey.
Background up front. I'll try to be brief but also informative. I have tuned one other car before, a chevy blazer (turbocharged by me) not using HP tuners.
current vehicle is a 09 Audi A4 2.0T QUATTRO. 250K miles. (Yup, that's right) had new turbo, pistons and rings (among other things from Audi at 80k due to buring oil and the class action lawsuit on that topic)
Major maintenance within the last 5k miles:
New timing chain and guides (febi)
New spark plugs NGK iridium (1 heat range colder)
New low pressure fuel pump (Bosch)
Upgraded high pressure fuel pump (034)
Cam follower
Motor mounts
Serpentine belt
Tensioner
Idler pulley
Maf (Hitachi)
New map
High pressure fuel sensor (bosch)
Pcv / oil separator and all new lines (Uro)
K04 turbo (brand new turbo)
Every single line, seal and gasket going to the turbo is brand new
New seals
valve cover
Vacuum pump
Upper/lower timing chain cover
Intake manifold
Throttle body
Injectors
I am leaving some things off but I think that is most of the major things. The coil packs are also upgraded R8 coils and relatively new, as are the injectors.
Sorry for the long history, but I am trying to give anyone willing to share some advice at least some of the story to work with.
I got a custom tune, but I have been having issues and the guy who tuned it has become unresponsive. I am having a significant drivability problem with what feels like a hesitation, stumble. This usually happens around 4k RPM and can be quite severe. Feels like the engine is going to drop out of the car or I slammed the breaks all of the sudden. It is also brief. So, it happens fast most times and then it's gone, making it extremely difficult to capture on a log. Rarely it will result in a few rapid ? spasms for lack of a better term, with the same behavior. I have a log file and the thing that I have notice consistently is an overboost condition whenever these events take place. I have checked the wastegate preload (it was off on the new turbo from the factory) I have set it correctly and it did help the issue. I also replaced the n75 valve with a new OE unit as the new one on the new turbo was also defective. That also helped, but it has not solved the issue completely. I think the rest of the issue lies with the tune. I have been trying to read other posts and get an idea what is going on but I would love to get some input from people on here that know more than me.
Sorry for the novel and thanks up front for any help you guys can offer.