GolfGTIforum.co.uk
Model specific boards => Golf mk5 => Topic started by: SteveS on 10 November 2008, 23:50
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its been buggin me because... i dont know the answer....
a dv valve. ok, it puts the air back into the intake before the turbo when foot is released from pedal...
blow off valve/spacer... just blows it into the air...
isnt a blow off valve bad for the car? or is it? better to have a dv to recerc the air?? :huh:
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AFAIK a blow off is bad because the various sensors are aware that a certain mass of air has entered the system, and if its just blown off to atmosphere it appears to the ECU that this air has just vanished so you might get error codes indicating a boost leak or similar.
I know that people fit the blow of valve to the 1.8T's and they seem to run OK for a while but then folks have problems when the ECU goes into limp mode.
HTH
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To my knowledge the only thing a blow off valve does is make your car sound like a Scooby :rolleyes:
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i know they just make a sound, but wasnt sure if they actually affect the car...
i know the MAS monitors the air from the intake... but if the dv just drops the air, how would it know?
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Any air after the MAF is metered, either by the MAF itself or the MAP (Manifold Absolute Pressure) sensor. Some cars deal with the loss of the pressure better than others and the more common reason for a VTA (Vent to Atmosphere) type valve is to alleviate turbo stalling.
1.8T's really don't like it. The 2.0TFSi isn't so bad but on the TFSi it's nothing more than a noise maker.
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on the TFSi it's nothing more than a noise maker
so it doesnt affect the performance or errors? i know it wont do anything but noise.. just curious.
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...
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It has something to do with putting air back to the turbo to keep it spinning so when you back on boost it can react quicker, dumping air out means the turbo will have to spin up again wasting time/power - something like that anyway...
Plainly the 1.8T and 2.0T have been designed to re-circ the air unlike other TC'd cars so its best to keep it that way.
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Plainly the 1.8T and 2.0T have been designed to re-circ the air unlike other TC'd cars so its best to keep it that way.
....Exactly! Isn't it even called a Recirculating Valve now?
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It has something to do with putting air back to the turbo to keep it spinning so when you back on boost it can react quicker, dumping air out means the turbo will have to spin up again wasting time/power - something like that anyway...
Plainly the 1.8T and 2.0T have been designed to re-circ the air unlike other TC'd cars so its best to keep it that way.
I understand, however DOES it ACTUALLY keep the turbo spinning, if its just put back into the intake, then its not exactly pushed into the turbo to keep it spinning.... i know thats the idea, but is it fact!
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:rolleyes:
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It has something to do with putting air back to the turbo to keep it spinning so when you back on boost it can react quicker, dumping air out means the turbo will have to spin up again wasting time/power - something like that anyway...
Plainly the 1.8T and 2.0T have been designed to re-circ the air unlike other TC'd cars so its best to keep it that way.
I understand, however DOES it ACTUALLY keep the turbo spinning, if its just put back into the intake, then its not exactly pushed into the turbo to keep it spinning.... i know thats the idea, but is it fact!
I would hope so!
Means the turbo is not having to work so hard so effectively using less energy, less fuel, less turbo lag.
Get a atmos valve and see ... :smiley:
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hum, i even spoke to awesome, and they said "If it makes any difference at all, It would be that margainal that you would need a Science lab to figure out the exact differences"
lol
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maybe it works better under cirtain circumstances - like when the is more boost or when WOT through the gears etc.
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they said "If it makes any difference at all, It would be that margainal that you would need a Science lab to figure out the exact differences"
Or an ECU, which can, and does tell the difference, and then throws a wobbler about it.
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they said "If it makes any difference at all, It would be that margainal that you would need a Science lab to figure out the exact differences"
Or an ECU, which can, and does tell the difference, and then throws a wobbler about it.
....Exactly! Awesome sometimes say some things which surprise me!
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they seem to think the ecu doesnt throw any errors up
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a DV doesn't put air back into the turbo on intake side to keep it spinning; a DV relieves the pressure between the turbo and intake manifold when the throttle.
without a DV, the compressed air will go back towards the turbo putting huge strain against the compressor fins and the turbine shaft aswell, as the air is going AGAINST the direction of rotation/air flow in the turbo. This will ultimately kill a turbo, or reduce its life severely.
a Vent to Atmosphere DV may not necessarily throw up any codes, but i would pretty much guarantee a worse MPG than with a recirc DV. This is because the ECU will expect the released air to still be "in the system" post MAF, but with VTA DV this is removed from the system. So the Air/Fuel mix will be slightly differently (more fuel, less air) = richer running, and potentially less MPG / Fuel efficient.
that's my view anyway...I'll let TT correct any errors!