I purchased an APR Chip for my 2002 Audi TT 225 and for the exception of a downpipe and 2.5" exhaust it is completely stock. My car runs perfectly fine in stock mode but when I switch to the high boost mode in the higher gears I have had a proble. When at full throttle around 5k rpm the boost will spike to about 20 psi. An audible stutter then occurs almost as if there is either an airflow restriction or a compressor surge and the boost will plummet to about 5psi.
I replaced my stock Bosch diverter valve with the forge diverter valve. It ran great but then after a few minutes the problems returned and still with no fault codes. What should be next plan of attack?
I am thinking that the Turbo Inlet pipe may be collapsing due to the high pressure as it collapses the boost gauge then reads a higher value as the area of the pipe is reduced.(Bernoulli's Equation) and the ECU simultaneously reads a spike and limp modes the car.

Does this seem plausible? I am opposed to the concept of a damaged compressor blade as the car runs fabulously in stock mode. Also, my forge diverter valve came with 3 springs and 2 shims but no instructions, what dv setup do you run?

 

I am having the same problem,but mine started happening after i installed the mbc. It puts the car in limp mode and i am only getting like 5psi. i had it set to 15psi (if i went any higher it would fail for some reason) and it worked fine yesterday, but on the way home just now it spluttered and lost all the air then boom, couldnt get the boost past 5!

Majorly pissed and tempted to just take the damn mbc off.

 

It seems as if we have the same problem. I called ecs tuning and they had recomended a diverter valve replacement (I should upgrade anyway so it wasn't really a big deal)in case of compressor surge, but that does not seem to be the problem.

 

stock diverter? try reversing its direction, might hold a little better. Sounds like it might be lifting.

Forge DV, chipped, try green spring, 2 shims.

BTW, if you're passing 15psi stock (with a MBC) you're definately putting your car into limp. Back it down 1-2 psi and you should be ok, and have enough buffer for the occasional spike that could put you into limp again. (happened to me on the highway w/ cruise on on the way back from H2O, scared the crap out of me)

TTooCool, you might be on to something with the turbo inlet collapse. Usually not a problem unless you're still using the stock airbox, just too much restriction.

 

these Are the reasons why I'm not going MBC.

 

im not stock bro, i have the apr stage 1, forge dv, 3" dp! I should be killing 15psi and going higher! no? without the mbc i was peaking at 19psi

 

AchTTung. I actually mean more of the inlet pipe leading into the manifold from the driver side side mount intercooler that is directly prior to where almost everyone (including myself) connects their gauge. If that pipe were to collapse it would show a massive spike in boost pressure even if a smaller massof air was being injected and then choke the engine out of fuel and cause a large pressure differential within the manifold. Thus triggering the limp mode. The stock airbox does not seem to be too restrictive and I think if that were the issue I would have noticed immediately after chipping not months later. I notice a lot of companies offer this hose and claim that it prevents the loss of boost at high rpm but no mention of spiking or studdering is mentioned.

 

hows a pressurized hose going to collapse? Only hose on these cars known/prone to collapse is the turbo inlet hose, and usually with the stock airbox still in use. I'd consider that before I thought about anything post-turbo.

Only other thing I'd think was maybe a hose seperating/cracked, but only noticeable at higher boost. Had that issue when I still had my 180 TT. Pressure test at 8psi revealed nothing, pressure did leak at 15psi though.

 

i dont know about all of you....but if im reading correctly the first guy is trying to run 20 psi through stock airbox....most definitely turbo intake pipe colapse....your trying to suck alot of air through a pretty restrictive factory airbox which is causing a big vacuum to be pulled in the turbo intake pipe which is rubber = colapse....get a shroom filter and call it a day haha. I mean you have spent 1000 bucks on making sure air gets out of your engine efficiently ....how bout some love for the intake side?

 

I purchased the Inlet Pipe today with a foam filter and it should be here in a couple of days. Until then it's just good old stock mode. I'll update you and let you know how it goes.