VAG 2.0 20V T - Question
17-05-2006, 12:50 PM
#1
It Wasnt Me!
Thread Starter
VAG 2.0 20V T - Question
Ive just read off someone that your 20v turbo VAG engine will run like crap as the engine doesnt like atmospheric dump valves, the ECU supposedly reads the recirculated air, I thought he got his wires crossed about airflow meters and dump valves as i thought a twin piston dump valve was fine on these cars?
here's how it goes:
Now, knowing not very much/nothing of the 20V turbo engine, I'd like to know:
A: Is this true what he sais
B: Why does it read the recirculated boost
C: I thought it was vented into the airbox, so then it wouldnt be much use, or is it vented somewhere else on a VAG 20V T?
cheers
here's how it goes:
Originally Posted by Him
the standard 20vT ecu looks for the unused pressure for goin back into the system, which would explain running like shit, stalling at junctions etc, remove and stick the standard recirculating type valve and your problems should go away, or invest in a decent adjustable recirculating valve and a remap.
Originally Posted by Me
Marcus, Why does the ECU look for the unused boost? and how?
Isnt it just a normal system where the unused boost symply gets (recirculated) back into the airbox!? without being metered (as their is not any point as it doesnt need petrol to ignite it?)
I know if you fit a dump valve to a car with an air flow meter before the turbo, it needs to be a twin piston. . as the dump valve is open on idle, and the engine is obviously on vacuum. . and sucks in unmetered air, so the ECU doesnt know what's happening and only fuels for the air that has passed the airflow meter! causing it run lumpy/stall on idle, and when changing down a gear/stopping at a road end!
Is that what you mean?
Isnt it just a normal system where the unused boost symply gets (recirculated) back into the airbox!? without being metered (as their is not any point as it doesnt need petrol to ignite it?)
I know if you fit a dump valve to a car with an air flow meter before the turbo, it needs to be a twin piston. . as the dump valve is open on idle, and the engine is obviously on vacuum. . and sucks in unmetered air, so the ECU doesnt know what's happening and only fuels for the air that has passed the airflow meter! causing it run lumpy/stall on idle, and when changing down a gear/stopping at a road end!
Is that what you mean?
Originally Posted by Him
Kind of Davie, the ECU does read for the pressure going back into the system going back through the MAF screwing the readings on that i'd reckon, haven't read much into the 20vT ECU parameters so can't really explain how to you Davie. But I've read and experienced the problems that everyone has talked about with the 20vT and thats due to the standard ECU being used with the dump valve, use a different ECU i.e. DTA or Emerald and the problem goes away.
Now, knowing not very much/nothing of the 20V turbo engine, I'd like to know:
A: Is this true what he sais
B: Why does it read the recirculated boost
C: I thought it was vented into the airbox, so then it wouldnt be much use, or is it vented somewhere else on a VAG 20V T?
cheers
17-05-2006, 01:16 PM
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a: yes
b: its a closed loop system, venting back to the atmosphere would simulate a leak post maf
c: vented back into the charge carrier usually
b: its a closed loop system, venting back to the atmosphere would simulate a leak post maf
c: vented back into the charge carrier usually
17-05-2006, 01:36 PM
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From experience i would run a Forge Dv007 costs about Ł80 pounds.
GFB do a what they call a Hybrid Dv.
But go for the Forge DV and a Carboni CAI and it will sound near enough the same
GFB do a what they call a Hybrid Dv.
But go for the Forge DV and a Carboni CAI and it will sound near enough the same
if thats what your after.
17-05-2006, 02:08 PM
#7
It Wasnt Me!
Thread Starter
Cheers for the info 
So what's a closed loop system? and why would they use it?
take it you dont mean closed loop as in non atmospheric?
Oh, not for me, Just the discussion came up on another forum and i'd never heard of it and wondered how it worked
So what's a closed loop system? and why would they use it?
take it you dont mean closed loop as in non atmospheric?
Oh, not for me, Just the discussion came up on another forum and i'd never heard of it and wondered how it worked
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17-05-2006, 02:18 PM
#9
The std AFM reads air, as you would expect and teh ecu then injects the correct amount of fuel into the engine.
When you close the throttle and teh dump valve goes off, the air flowing out of teh dump valve flows past the airflow meter and the ecu injects fuel for it... Instant rich problem.
The std system recirculates the air so the meter doesnt see and mass change.
When you close the throttle and teh dump valve goes off, the air flowing out of teh dump valve flows past the airflow meter and the ecu injects fuel for it... Instant rich problem.
The std system recirculates the air so the meter doesnt see and mass change.
17-05-2006, 02:18 PM
#10
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Thread Starter
So it's as simple as:
You cant use a atmospheric dump valve on any car inc the 20vT with std management that incorps the airflow meter?
I thought their was something different about these that meant you couldnt use a twin piston atmospheric
You cant use a atmospheric dump valve on any car inc the 20vT with std management that incorps the airflow meter?
I thought their was something different about these that meant you couldnt use a twin piston atmospheric
17-05-2006, 04:05 PM
#11
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Thats the end of it mate but as i said have a look at the GFB Hybrids.
But...
On the earlier Non DBW 1.8t like my old one with the engine code AGU you could run an atmospheric and not through any errors but when remapped they would??
But...
On the earlier Non DBW 1.8t like my old one with the engine code AGU you could run an atmospheric and not through any errors but when remapped they would??
17-05-2006, 04:15 PM
#12
It Wasnt Me!
Thread Starter
cheers stu, that's how i understand it, i just thought the 20v turbo system was more complicated!
cheers also smithy, doesnt make sense to me either, the fault code/remap thing
cheers also smithy, doesnt make sense to me either, the fault code/remap thing
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