S3 Under Boosting, Changed MAF, no improvement :(

[SamiG]

Okay so some of you may know i took my S3 up to leicester at RTech for a Stage 1 remap a couple weeks back.

Couple long stories short it didn't end up getting mapped because they found that the car was down on power (only producing 198hp) and was significantly under boosting.

A few things were ruled out (N75, actuator etc) and i was sent away with the advice of changing the MAF sensor and possibly the MAP sesnor.

I'm no mechanic and only have basic knowledge of engines so this was all new to me but i ordered a new genuine MAF and fitted today in hope of a power improvement.... There was none

Has anyone had this problem and may have and suggestions for me as i need this sorted before i can get it mapped

RTech is a good 3hours each way for me and i don't know anyone with VAGcom to log requested boost vs actual boost to check if it's boosting correctly.

Any help guys??

 

[Fahim]

It could be a boost leak?

Have you tried making a DIY boost leak tester and using a compressor to pump your system in with 10-15 psi and listening to leaks?

I made one myself last week using a 3inch to 2inch rubber coupler, a PCV cap (both from plumbing shops £7 in total) and a free tire valve from my local tire shop.

Bish bash bosh, and you can check boost leaks in a jiffy.

 

[karbonk]

MAF is definitely the first thing to rule out and does it a world of good to change anyway and cheap to replace. Making any noises, hissing? Could be loosing boost. Split hose, turbo?
When did it have a Service. Plugs, oil, filter etc?

 

[SamiG]

It was tested at RTech with a smoke test for leaks which gave no leaks at all :-|

A mate of mine that works at VW seems to think a split vac hose could cause this issue? Is that right??

 

[Sandip]

Have you got a boost gauge on it bud? What is it boosting?

 

[s3dave]

Really needs data logging to find the issue have youlooked on the vcds user map?

 

[Welly]

It was tested at RTech with a smoke test for leaks which gave no leaks at all :-|

A mate of mine that works at VW seems to think a split vac hose could cause this issue? Is that right??

Split hoses can cause issues, but it would be very unusual for it to cause under boosting of the turbo. Split in the actuator piping/N75 piping/DV piping would generally cause it to overboost.

 

[SamiG]

It was serviced 3 weeks ago with oil/filters/plugs/fuel filter etc

I don't know anyone with VAGCOM to do the datalogging

MAF has made no difference at all :-|

And no, i do not have a boost guage on it either...

 

[s3dave]

http://www.audi-sport.net/vb/vcds-formerly-vag-com-forum/84603-%2A%2A%2Avcds-users-map%2A%2A%2A.html

 

[SamiG]

:thumbsup:

Thanks dude!

I PM's a couple of people

 

[[Dave B]]

Could be electricaly related i.e. coilpacks. VCDS will show you the way though.