Hi. I got a little issue on my S4 b5. Its Stage II+ with an APR tune.

Since a few days my car boosts only 8 - 11 psi and i donīt know why, there are no codes, cels, boost leaks, vag says nothing is wrong. Turbos sound good. I have new plugs, egtīs, maf and all of them work well. I checked nearly everything, o2īs are allright so the coils are. I am running out of ideas.

So WTF is going on?
Anyone has an idea?

 

hey buddy, check my thread for EGT sensors... it sounds exactly like what mine was doing..
if you have vagcom, go to measuring blocks 112, 114 and 115. when you just fire your car up the temps for both banks should read 945 degrees celsius. if one or both of them is glitching back and forth between that temp and 1035 degrees, you have a bad egt.. then if you get on it and demand full boost when the temps are glitching, your wastegate duty cycle percentage will go up and limit your boost to around 10 psi.. and your probably dumping fuel out the tail pipe.. so see if its black back there and your running rich...

 

and i saw your egt's are new.. but check their numbers just to be sure...

 

Hey, thanks for your reply, but i checked the egtīs with vag and they are allright and there is no black smoke coming out of the exhaust, so the arenīt the issue.
Andyid on s4froum had the idea to check my dvīs, i havenīt done that yet, iīll check out tomorow, but i hope they arenīt the issue, because i have the apr r1īs. What do you think?

 

Yah, I agree with ern, EGTs can be pretty elusive. Mine looked perfect on the VAG, but would cripple my boost around 4k rpm when hammered. Replaced EGTs...everything ran perfect...it may not be your problem, but even if you're not throwing codes and your temps look normal, they can definitely still be bad.

 

I have no plan anymore, today the car drove like a rocket again, i was totaly happy, but as i started it again for another drive later it drove only with low boost again, i am running out of ideas.
WTF

Iīll try to change my egtīs once again. I hate all this electronic stuff, but on the other side its for the performance too. The dvīs are allright woooohooooo.

Are there any upgraded egtīs or can use some rs4 egtīs?
Anyone has some other advices for me? Is there something else except the egtīs what can be broken and cause my problem?

 

man, sounds like classic EGT glitches.. you can get them tested good guaranteed from shokan for like 125 a piece.. but id leave vagcom hooked up at all times, then just look at those measuring blocks 112, and see if you see any slight glitches. go to advanced measuring blocks and graph it that way if it glitches really quick and you miss it, itll still be showing on the graph.

 

Allright, iīll check the egtīs again.
Another idea, do you think that the N249 can cause such problems?

 

i wouldnt think so, but if it did i think it would set a definite code. a solenoid shows up as a malfunction pretty easily on vagcom, sometimes sensors, like a maf , o2 or EGT can become degraded and still somewhat work and not set a fault code.. so the ecu believes it to be true.. an ecu picks up on a three wire solenoid with some sort of duty cycle signal that is to be returned to the ecu..

 

n249 works good. iīll check the car with vag today again and weīll se what the egtīs say.
Iīll let you know.

Thanks so far.