Specified v Actual boost v N75 help reading logs

[Phillyf21]

I'm experiencing a weird boosting issue with my Shark Stage 1 2007 TFSI. It started a few months ago with an intermittent issue when on the odd occasion I wouldn't get full boost at WOT. It went away but then came back a few months later but this time I wouldn't get full boost if going WOT over 3k RPM, under 3k it was fine. Now I can only get full boost if I dip my clutch and blip the revs a few times past 5k RPM then if going WOT under 3k RPM I'd get full boost for a few blasts then its gone again. Only stored code is a P0101 MAF sensor (G70) Implausible Signal.

Managed to log specified v actual boost v boost pressure (waste gate duty N75). You can see in green (from 2k RPM) a good pull, bit of a delay hitting actual but gets there and pulls hard. In red (from 3k rpm) never hits the actual and the N75 readings are lower at the beginning of the pull. I also think 2300mbar (33 PSI) is way to high for a K03 stage 1 remap?

  Anyone make anything of this? Bad turbo? Faulty N75 valve etc?

[pudding]

I think the MAF fault needs investigating before going any further.  It's either faulty or there's a wiring issue.  You won't get full power with a bad MAF.

The actual boost is 1.3 bar, or a shade under 19psi.  VW ECUs measure in absolute pressure, so you have to deduct 1 bar to get your gauge pressure.

It is indeed a little sluggish to hit the midrange targets for a K03.  You might want to see if there's oil leaking out of the intercooler connections, which indicates a boost leak. 

[Phillyf21]

I think the MAF fault needs investigating before going any further.  It's either faulty or there's a wiring issue.  You won't get full power with a bad MAF.

The actual boost is 1.3 bar, or a shade under 19psi.  VW ECUs measure in absolute pressure, so you have to deduct 1 bar to get your gauge pressure.

It is indeed a little sluggish to hit the midrange targets for a K03.  You might want to see if there's oil leaking out of the intercooler connections, which indicates a boost leak.

Thanks for the reply. I'll log the MAF and take it from there. I did notice a bit of oil in the IC pipes when I pulled them to check for tears.

[Phillyf21]

Just been out and unplugged the MAF and the car ran no different. I still had to free rev up past 5k then I got full boost again at WOT. Don't think its a boost leak then. More than likely a sticking actuator I think. Is there anyway to run VCDS on the actuator itself to see if its getting its full travel?

[pudding]

Clear the fault codes and see if the MAF fault comes back.  If it doesn't, it might be OK.  Could be a historical fault.

Oil in the boost pipes is normal but if it's weeping out of the connection, that needs fixing.

You can only monitor the N75, but that doesn't necessarily mean the actuator is moving as commanded.  That can only be checked physically unfortunately.  You can drop the  downpipe and connect up a miti-vac type hand pump to the wastegate diaphragm and check the penny valve opens and closes as expected.  A good excuse to knock out the precat whilst you're there!

[AdamGwynne]

Just been out and unplugged the MAF and the car ran no different. I still had to free rev up past 5k then I got full boost again at WOT. Don't think its a boost leak then. More than likely a sticking actuator I think. Is there anyway to run VCDS on the actuator itself to see if its getting its full travel?

Hi Philly, tried messaging you on your breaking sale post but couldn’t get anywhere. If you’re interested in selling your BBS wheels and Revo intake please reply here or message me on Facebook which is Adam Gwynne (Coventry).

Cheers.

[Phillyf21]

Hi Philly, tried messaging you on your breaking sale post but couldn’t get anywhere. If you’re interested in selling your BBS wheels and Revo intake please reply here or message me on Facebook which is Adam Gwynne (Coventry).

Cheers.

@AdamGwynne yeah no problem on wheels and intake. Drop me a text 07740177403.