Boost reading on idle? - Update

[TIGER-UPPERCUT]

Hi,

Ive got a boost gauge fitted, on idle when the car is warm Im sure it used to read -20psi however over past few days Ive noticed its now reading -23psi.

Would be helpful if people can see what their GTI is reading when on idle as I think I may have a boost leak.  Strange as Ive just had the divertor valve replaced for a 'G' type.

Thanks

[scopes]

On tick over when 1st starting up it would sit around 20 then drop when the auto choke goes off...

if that helps!

[john_o]

-20-22 normal for me
higher neg value = more vacuum
if you had a vac leak it would be a lower value not greater, greater is better

[TIGER-UPPERCUT]

Hi John_O thanks for the reply.

Funny thing is that the car used to hit peak boost of around 12-13psi (Stock 06 GTI no mods)...now it only hits 10psi max in any gear .  Cant get it to go any higher.

Im sure this has been after I had my 'G' type divertor valve fitted.....might get it checked to see if its been fitted correctly.

[M5 London]

I have a feeling that these variances in your idle (Vacuum readings) and max boost readings are also correlated to the weather and mainly atmospheric pressure.

Try to see what Atmospheric Pressure has been over those days by going to the Met Office site or similar.

Also if you suddenly find yourself in high altitude areas you will see a similar situation, i.e lower atmospheric pressure.

Just a thought .....Your new diverter valve has given you slightly better vacuum readings (In.Hg) which is understandable.  But recently we may have had lower atmospheric pressure (mBar) which will lower peak boost readings.

[TIGER-UPPERCUT]

I have a feeling that these variances in your idle (Vacuum readings) and max boost readings are also correlated to the weather and mainly atmospheric pressure.

Try to see what Atmospheric Pressure has been over those days by going to the Met Office site or similar.

Also if you suddenly find yourself in high altitude areas you will see a similar situation, i.e lower atmospheric pressure.

Just a thought .....Your new diverter valve has given you slightly better vacuum readings (In.Hg) which is understandable.  But recently we may have had lower atmospheric pressure (mBar) which will lower peak boost readings.

Hi M5,

I had no idea that atmospheric pressure affected maximum boost or the car in any way.

Think I am going to record some runs on VCDS and see what that shows...

[M5 London]

I have a feeling that these variances in your idle (Vacuum readings) and max boost readings are also correlated to the weather and mainly atmospheric pressure.

Try to see what Atmospheric Pressure has been over those days by going to the Met Office site or similar.

Also if you suddenly find yourself in high altitude areas you will see a similar situation, i.e lower atmospheric pressure.

Just a thought .....Your new diverter valve has given you slightly better vacuum readings (In.Hg) which is understandable.  But recently we may have had lower atmospheric pressure (mBar) which will lower peak boost readings.

Hi M5,

I had no idea that atmospheric pressure affected maximum boost or the car in any way.

Think I am going to record some runs on VCDS and see what that shows...

I may be wrong, but I see it as :

Lower Atmospheric pressure, less air per unit volume, thus the result after your Charger compressing the said, less air per unit volume, would result in less peak boost pressure   

[TIGER-UPPERCUT]

Had a closer look today the problem looks to be my boost gauge itself. On the opening sequence when you turn to ignition before starting the car it's supposed to sweep from max to min then settle at 0. It doesn't settle at 0 it stays at -4. It looks like it maintains this even when the car is started and running.

Seems to add up as even though the boost gauge is reading lower boost the cars performance seems the same as before.

Going to check the wiring, not had it long so Shud be under warranty.