I' ve got an X50 with Cargraphic/Rs tuning exhaust and flash to 1.1 bar.
Car runs great in all conditions but i've a strange problem: When i push at WOT in 6th gear and when the car hits 6400 rpms and 190 Mph boost drops from 1.1 bar to 0.6/0.7...This is limp mode because when this happen the car only boost 0.6/0.7 in all gears until i stop the engineand turn the key off.
My tuner has replace N75 valve and set wastegate actuators properly but the problem is NOT resolve ?!?
The strange thing is that the car goes in LIMP mode always when it's at WOT at 6400 rpms /190 mph in 6th gear ..
NO CEL and NO codes...?!?

 

Can you data log it? You can do 200mph on a dyno . Have your tuner try that. Safety first.

 

Most likely a tuning problem ...the limits in the ecu have to be raised

 

Joe is probably right... absolute boost map... not to mention Mass air flow maps that actually control the boost as well .. if these values are not not raised enough it will cut the boost... etc...
why dont you lower manually the boost via Wg actuators so you only run .9 bar max.. see if that does the job.. if so then its in the ecu... did you put on after market WG actuators?

 

HI,Just curious,,Could you tell me what you cars MPH is at redline in 5th gear? Mine Redlines at 181mph in 5th......I have not had the room to get it over 190 yet....Thanks...

 

Mines now recently done the same. How do I get it out limp mode? because there are no codes stored my car is stuck boosting to just 0.4 bar now

 

Marksky that's my idea also..

I'll try to do this... Thanks

 

John my "redline" / rev limiter is at 7150...so theorically i can do 173 mph.
Usually i shift at 7K so in 5th gearis 168 mph.

 

Hi,Thanks....My rev limiter is set at 7400 RPM...I have hit that in 5th gear several times and my speedo reads 181mph then....I can not wait to find a open stretch of road and safe to hit the rev limiter in 6th.........i have to do that before you beat me in breaking more then 190mph..lol...

 

maybe it's a simple as your boost recirculation valve has failed or is failing. per that other thread, and similar symptoms. they go bad, and cause these cars not to fully boost.. no? ( although i have NO business talking parts here...)

 

What is this valve that you have mention ? Maybe N75 valve solenoid ? If so i have replace N75 but the problem still continue..

 

I' ve hit my 7150 rpm rev limiter in 6th one time before this boost problem on GERMAN Autobahn and the speedo shows 212 Mph (341 Km/h) / REAL speed of 206 Mph (331 Km(h).
Looking this thread https://www.6speedonline.com/forums/...modded-tt.html
with your 7400 rpms rev limiter if you hit it in 6th gear (with 626 rwhp you do NOT have problem to do this) your REAL speed shoul be 213 mph ( 342 Km/h) but speedo only shows MAX 212 Mph ...
But I shoul never do this in USA road..
NOT after looking this video clip

 

i believe they ( the valve(s) n75 ) are one and the same and it may be a different terminology from US to UK/europe?. but this thread has experts contributing, so i'll leave that for them to clarify.

 

Disconnect the battery for 15-20 minutes

BUT - Make sure you have the ignition on when you disconnect it, otherwise the back-up alarm will go off and pierce your eardrums!!

 

Your car continue in LIMP MODE also after you have turn off the key and stop the engine ?
this is STRANGE....Mine retun to run well after i turn off the key.