Lower than expected boost on a cold day.

[Wobbly Dave]

I took Justin out in Betsy just after we finished at the WM Xmas meeting. Betsy did OK but I was showing J the TORQUE Android App. I have recently fitted a new MAP sensor (manifold air pressure), which I believe is what is read & shown on the app. However I only made 15psi - (1 bar) on 3 to 4 degree ambient, where on tests a month earlier with 10 degree ambient I was making about 21psi. So later this evening - I went out again & reproduced the same results.

Do you think there is a cold limit thing here? Is Betsy showing me up? Is the TORQUE app wildly inaccurate? Or do I just have a boost leak somewhere?

Hopefully find out from a seondary source as I am off to HLM tomorrow on a hunt for a heater matrix amongst other small maintenance issues.

Humph.

[M-R-P]

Might be worth chucking the old map sensor back in to see if it goes back to normal. You'd know if your new one is shot then. Next would be boost leak i suppose.

[Wobbly Dave]

hmm - my internal thinking goes back to the fact that the usual healthy hiss from the recirc valve seems a lot quieter.

In fact on play back - you can bearly hear it

Edit - I think my mind is playing tricks - it is there but it is very difficult to quantify.

[M-R-P]

Which would imply lower boost, which would, in turn, imply the map sensor could be ok.
What about the vac pipe to the recirc?... No, you'd hear it hissing as soon as the compressor spoils up.
Hmmmm...
Map playing up? Can it?
Leaky i/c? Didn't damage it when you sat on it did you? Lol

[Wobbly Dave]

Even my arse isnt that big - lol

[Wobbly Dave]

Come to think of it - I did loosen the bottom clip for the FMIC when I put the new coolant hoses on. I swear that I retighted it. Oh god - I am gonna loose sleep thinking about the ridicule if I forgot.

It is unlikely to be the new MAP sensor - as I tested it after fitting & everything was fine.

[M-R-P]

Pmsl. Maby Hamish will have an idea.
My knowledge is limited to the things I have to fix on my own car and the few substantiated snippits of info I learn here.
Hope you get her sorted mate.

[M-R-P]

Ooh.. charge air hose? Mine go pop when I forget to tighten it.
By map playing up I meant ecu map, don't know if they can play up?

[Wobbly Dave]

Gutted really after been blow away by the ferocity of the RS4 - Betsy did not do herself justice.

[Wobbly Dave]

Ooh.. charge air hose? Mine go pop when I forget to tighten it.
By map playing up I meant ecu map, don't know if they can play up?

That's why I was wondering if such a thing as a cold weather protection jumps in - but that doesn't seem logical or probable.

[M-R-P]

RS4 is in a different league mate, twice the cc and 4wd. Don't beat yourself up over it. There are some things a T5 won't beat

[smithy]

but a 940 might have a chance lol

[Wobbly Dave]

Well I will have to resign myself to the fact that I am not going out at this time to jack up Betsy to check a jubilee clip. Too cold - too dark & too tired. I am going off to bed & will face it tomorrow.

I shall have to console myself that Betsy still makes 300 on 1 bar - even if the torque is slightly down she is still rapid.

[M-R-P]

That's a drag race I'd like to watch

[Dangerous Dave]

Theres lots of parameters the ecu takes into account, intake air temps affect how the ecu determines 'mass of air absorbed' so I'm guessing that the ecu will perhaps adjust the turbo output.

I have read somewhere about some ME7 principles, but they didn't go into too much depth.

Also this on wiki
http://s4wiki.com/wiki/Tuning#IAT_ef...equested_boost

[smithy]

my car works on the colder it get the faster the car goes lol

[Wobbly Dave]

That is what is bothering me.

[smithy]

That's a drag race I'd like to watch

1 day you never know lets see how the old girl goes in the new season mate

[smithy]

That is what is bothering me.

i think your boost pipe is loose mate

[Justin]

but a 940 might have a chance lol

Everything has a chance smithy, one mistake by me and the race is yours lol.

Gutted really after been blow away by the ferocity of the RS4 - Betsy did not do herself justice.

I was quite impressed with yours Dave, it pulls hard and felt good to be back in an oblob.