Boost not levelling off???

[bakersdelight]

I did a few runs today using the OBD2 bluetooth dongle and Torque app on my android phone, I used Torque to plot my boost level against time, and this is what I got:



Instead of reaching a certain level and then levelling off, it appears that my boost would just keep climbing up until I let go of the accelerator... is this normal? Is my wastegate not doing its job? I got APR Stage 1 tune...

I also recorded a peak boost of 28.2PSI!!! that is like 2 bars!!! I hope that was just a false reading.... or over-boosting??

[noone]

The wastegate is controlled from the N75. I would be surprised if you were able to generate that much boost.

I dont know the device youre using, so it could be something to do with that, dodgy sensor (although if it was you'd probably end up in limp pretty quick).

Assuming its using the MAP sensor, it wont show below ambient pressure, so the info above would indicate 30 units. As it does not say PSI, might want to confirm that. The K03s would struggle to produce more than 22 psi near the redline.

Can the device be calibrated to different vehicles? I believe that the block 115 is right for our vehicle. Boost generally comes on close to 2k rpm.

[bakersdelight]

The wastegate is controlled from the N75. I would be surprised if you were able to generate that much boost.

I dont know the device youre using, so it could be something to do with that, dodgy sensor (although if it was you'd probably end up in limp pretty quick).

Assuming its using the MAP sensor, it wont show below ambient pressure, so the info above would indicate 30 units. As it does not say PSI, might want to confirm that. The K03s would struggle to produce more than 22 psi near the redline.

Can the device be calibrated to different vehicles? I believe that the block 115 is right for our vehicle. Boost generally comes on close to 2k rpm.

I set my Torque app to calculate boost level using ALT method, the other two options are MAP(default) and MAF, however, only ALT can produce a reading, the other two give no boost reading at all...

the ALT boost reading also gives negative pressure, when the car is idling, it is normally around -12 to -13 PSI... so the 28.2PSI I recorded would be absolute positive pressure, not relative pressure to the idling baseline...

[noone]

I'd try and find out what the ALT method is, sounds like its seeing the vacuum in the manifold.

[bakersdelight]

I'd try and find out what the ALT method is, sounds like its seeing the vacuum in the manifold.

thx... but in theory, boost should level off after a certain point when the wastegate kicks in, right? It just doesn't look right that it keeps building up until throttle is released...

[h100vw]

thx... but in theory, boost should level off after a certain point when the wastegate kicks in, right? It just doesn't look right that it keeps building up until throttle is released...

Unless your wastegate is set wrong, I doubt you are making 28 PSI. It would be horrible to drive too.

There's always a problem when you have too much information to look at, you start analysing it too deeply. If you want to see what's going on, use a VCDS lead and log it.

Log blocks 020 031 and 115 together with the lead for some meaningful information.

Gavin

[bakersdelight]

I am using the OBD2 bluetooth dongle with the Torque app to monitor my boost... I managed to get it to read boost using the MAF method... and now the readout shows boost peaks out around 18.2 PSI...

With an APR Stage 1 ECU tune, is 18 PSI a reasonable max pressure? so should I start looking for boost leak?

[VWindahouse]

Funny you should ask

http://www.vwwatercooled.org.au/foru...a-75730-3.html

I would say that's about spot on

[noone]

Sounds about right. The MAF uses a combination of the MAF air flow and something else (like fuel injector cycles) to estimate.
Have you upgraded your intake at all?

APR tunes for the Polo have been known to be a little more conservative, by a KW or 2, in this case maybe a PSI or 2...

[bakersdelight]

Thanks guys for your responses...

As for my intake, I got PD160 and K&N drop-in....

However, the car feels less powerful on APR's full tune compared to the 6 hour trial tune... Please see this thread:
http://www.vwwatercooled.org.au/foru...ial-75820.html