Dump valves and overfueling
#1
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Dump valves and overfueling
The answer why a Blow off valve or VTA makes a car run rich on the over-run is because the Vacuum effect of the Turbo momentarily draws air past the MAF after the throttle is closed and the ECU fuels for it.
On a re-circ BOV the re-cycled air cancels out the vacuum pressure of the Turbo and thus stops new air entering past the MAF.
Jury is still out on a Dump Valve delete and what PSI it would start making the car have a rich fit.
Courtesy of joshnosh!
On a re-circ BOV the re-cycled air cancels out the vacuum pressure of the Turbo and thus stops new air entering past the MAF.
Jury is still out on a Dump Valve delete and what PSI it would start making the car have a rich fit.
Courtesy of joshnosh!
Last edited by RS_Matt; 03 January 2014 at 02:30 PM. Reason: To show 99% of Scoobynet users have no friggin clue.
#4
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But with the throttle still closed that air isn't going back into the inlet anyway?? why does it matter where the air shoots off to? Into the engine bay or towards the turbo/airbox.
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#8
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Yes but when you let off why does it make a difference where the metered air is, the engine won't be using it either way?
#11
Get a better ecu like a syvecs, that lets you remove the maf sensor and you can throw the air about wherever you fancy!
Atmospheric dump valves and maf sensors just don't get on.
Atmospheric dump valves and maf sensors just don't get on.
#13
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When does the car overfuel, as long as the ecu thinks the pressurised air can be used? split second back on boost?
#15
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People can tell me the MAF has calculated the air all day long, that a VTA causes rich running, that VTA's don't work well with MAF's all day long or a VTA causes non smooth running it won't answer the why or when. I've been reading the same crap for years, it's the same BS that STI owners throw at the capable Newage engine and gearbox.
Last edited by RS_Matt; 01 January 2014 at 05:17 PM.
#17
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Also with a re-circ does the dumped air rush back to the intercooler or back to the airbox?
Last edited by RS_Matt; 01 January 2014 at 06:15 PM.
#19
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But a re-circ vents air away from use, what is the difference? it must be just me lol
#21
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Sorry to jump in but has anyone got a link to the best place to get a syvecs ecu from ?
Can it just be plugged in job done ? Or foes it need some additional works ?
Thank you
Just out of interest what does a dump valve do ? Lol just kidding
Can it just be plugged in job done ? Or foes it need some additional works ?
Thank you
Just out of interest what does a dump valve do ? Lol just kidding
#22
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It prevents lift off det and cools cylinders before going back on boost. As a bonus it keeps air flowing the right way to the inlet, relieves stress on turbo blades and or bearings and creates a pleasing air-hydraulic pastiche sound.
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Would you mind confirming that mine is a bov and not a recirculating ?
https://www.scoobynet.com/general-te...ted-wrong.html
I'm concerned that the fact mine isn't recirculating is the reason I'm having issues with the current performance in general
https://www.scoobynet.com/general-te...ted-wrong.html
I'm concerned that the fact mine isn't recirculating is the reason I'm having issues with the current performance in general
Last edited by ScoobyFanatic33; 01 January 2014 at 07:33 PM.
#25
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a recirc "Recirculates"the air that has already been measured by the air flow meter,it simply recirculates within the system before the turbo ,it does not exit the metered system,if it did exit or (vent to atmosphere) the calculated fuel with be too much fir the air that has already been measured
The only thing I can think of is that on a re-circ set up the moving pistons on the overrun are drawing in slightly more air from the reserves in the intake and I can't see why a deleted system would run rich using this rhetoric.
#26
#27
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It's not plug in and go, needs mapping and sensors depending on what you want from it.
#28
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Would you mind confirming that mine is a bov and not a recirculating ?
https://www.scoobynet.com/general-te...ted-wrong.html
I'm concerned that the fact mine isn't recirculating is the reason I'm having issues with the current performance in general
https://www.scoobynet.com/general-te...ted-wrong.html
I'm concerned that the fact mine isn't recirculating is the reason I'm having issues with the current performance in general
#29
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...but when you suddenly come off boost that metered air isn't used either way. I can only see a leaky DV causing rich issues and that would be on moderate to elevated boost.