ecu restricting boost??

[malcolm30029085]

hi i have started many threads about this ongoing issue with my apy s3.

basicly the car will only boost to 10psi exactly!!
checked for leaks
changed maf
changed dv valve
changed n75 valve
checked turbo and wastgate!!!!!!!
i disconnected the acutator pipe and drove it (unlimmited boost) and it was fine drove perfectly and boosted well past 10psi!!
yhe only thing not standard is a de-cat it has not been mapped would this be the cause of it????????
cheers

 

[Welly]

Hmmmm, hard to say. The N249 valve also deals with boost control, so may be worth bypassing as a test.

Have you scanned it for fault codes?

 

[Welly]

Have a look at this for the N249 bypass: http://www.audi-sport.net/vb/showthread.php?84402-N249-Bypass-How-To-(2000-S3-but-same-for-many

 

[badger5]

bring it down and I can take a look

 

[Welly]

^^ I'd go with that personally....

 

[malcolm30029085]

bring it down and I can take a look

Ok mate where abouts are you??
Forgot to mention that I have done the bypass and also have a brand new map sensor on there aswell!!

 

[malcolm30029085]

just a quick update i have the car booked in at mrc tunning in banbury next week so hopefully they can she some light on it, also just thought id mention that the car actually struggles to do 80 on the motorway let alone put you back in your seat!!!

 

[Boggle]

i had trouble going over 60 and got it fix was told it had a hole in a pipe going to the turbo hope this helps

 

[Welly]

i had trouble going over 60 and got it fix was told it had a hole in a pipe going to the turbo hope this helps

****** hell, that must of been some serious kind of hole....

 

[Welly]

just a quick update i have the car booked in at mrc tunning in banbury next week so hopefully they can she some light on it, also just thought id mention that the car actually struggles to do 80 on the motorway let alone put you back in your seat!!!

Yeah, hopefully they can tell you. Sounds like it's going in to limp mode to me to be honest, but they will be able to tell you more.

 

[malcolm30029085]

Yeah, hopefully they can tell you. Sounds like it's going in to limp mode to me to be honest, but they will be able to tell you more.

yhe thats what i thought but dont understand whats setting it off???

 

[Welly]

yhe thats what i thought but dont understand whats setting it off???

Could be a million things. OK, not a million, but plenty of things can cause it.

Overboost being one of them.

May not be a faulty N75 valve on your motor, may be the ECU keeing the N75 valve open to invoke limp mode, landing you with your problem.

10 PSI is a lot for limp mode - but maybe someone has 'fixed' the actuator to make it open at higher boost pressure.

This would account for your overboost, as well as 10 PSI in limp mode....

Just my thoughts.

The other, and most obvious possibility is that the ECU is giving you limp mode as it things the cat is shagged...

 

[malcolm30029085]

Could be a million things. OK, not a million, but plenty of things can cause it.

Overboost being one of them.

May not be a faulty N75 valve on your motor, may be the ECU keeing the N75 valve open to invoke limp mode, landing you with your problem.

10 PSI is a lot for limp mode - but maybe someone has 'fixed' the actuator to make it open at higher boost pressure.

This would account for your overboost, as well as 10 PSI in limp mode....

Just my thoughts.

The other, and most obvious possibility is that the ECU is giving you limp mode as it things the cat is shagged...

yhe that would make sense, well see what mrc has to say on sat i will let you no what is was when i do!! cheers

 

[mark_sarah]

Any news on this?