What triggers overboost?

[AndyP]

Not overboost protection, but the overboost function on the ABY engine?

When I was driving back from the garage meet on sunday I noticed that the overboost was not working, even with my foot to the floor it was only showing 0.8bar boost, whereas with the over boost it should go to 1.1bar I believe.

Is this triggered purely by the TPS hitting 100% or are there other variables involved?

[Jamo]

what gear were you in? you only get overboost in higher gears 4,5,6 (can't remember if you get it in 3)

[Greg_S]

i think it is when the ECU senses a high load and WOT, but dont quote me on that one

[AndyP]

Couldn't get it to work in any gear. I know the throttle is physically opening 100% but I don't know if the TPS is telling the ECU that.

[S4-Sleden]

I think it depends on how quick you floor it too...........

[Jamo]

No it's defo load related, S2entral.net test for it is to floor it up a hill in 4th gear and you should see 1.1 boost

[Jamo]

See here for a test: http://www.s2central.net/motronic_boost.html

[Olle]

WG solenoid valve?

[Jamo]

WG solenoid valve?

waste gate frequency valve, search for wgfv on the forum

[Olle]

yep, you are correct, i meant WGFV. it also does trigger overboost, right?

[slow2]

Not overboost protection, but the overboost function on the ABY engine?

When I was driving back from the garage meet on sunday I noticed that the overboost was not working, even with my foot to the floor it was only showing 0.8bar boost, whereas with the over boost it should go to 1.1bar I believe.

Is this triggered purely by the TPS hitting 100% or are there other variables involved?

Hi Andy
along my way to me becoming motronic guru i have discoverd that the altitude sensor readings affects overboost function on the ABY
i have just removed mine in order to do resistance check will let you know what i find out

[S2central.net]

More correctly the altitude sensor can affect all boost values because the ECUs pressure sensor works off absolute pressure... so if the alt sensor is giving a false high reading then the ECU will not allow as much boost to hit a target absolute value. Thats roughly as I understand it...

I also understand that rapid opening of the throttle in high gears is needed to engage the overboost mode - which lasts about 15 seconds on factory chips.

With VAGCOM you can check to see if the throttle positions are being correctly registered by the ECU.

IDLE = 0001
PART = 0010
WOT = 0100

Those are from memory - check s2 central tech areas for info I compiled years ago... which probably needs a tidy up but such is life !

[Ski]

Normally the right pedal =p

[Jamo]

Funny that i mentioned to another forum member to check the altitude sensor the other day!

[slow2]

Funny that i mentioned to another forum member to check the altitude sensor the other day!

And i did, although Paul N had already advised this as possible cause for my boost problem earlyer in the day