BOV myths
20 January 2010, 12:54 PM
#1
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BOV myths
Sorry if this is a repost.
but i found this on a search on google. Lets the questions and answers begin
*flame suit on*
http://www.hondacivicforum.com/forum...ad.php?t=72147
but i found this on a search on google. Lets the questions and answers begin
*flame suit on*
http://www.hondacivicforum.com/forum...ad.php?t=72147
Last edited by motorola222; 20 January 2010 at 01:01 PM.
20 January 2010, 01:57 PM
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Yeah exactly most of u elders do know it's just usefull for us newbs who don't. My main concern is everyone claims to think or know that vta valves damage the cars. Whernis the proof?
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20 January 2010, 02:11 PM
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Originally Posted by Someone
On many cars, the air is metered by a device called a MAS/MAF before the turbo inlet. If this is the case on your car, venting your BOV to the atmosphere can result in an inaccurate count of the air entering your engine, resulting in a rich condition after each shift, damaging performance. On some cars it won't be noticeable, but on some cars it will cause the engine to stall instantly. On all cars with pre-turbo MAF/MAS, it is officially "incorrect".
If this is the air metering method in your car and you want the "PSSSHHHH" noise, you would be better off installing an open-element air filter, since it is the airbox on most cars that stifles the blow off noise.
If this does not give you the desired effect, you might try changing your BOV to one of our aftermarket BOV's that is capable of recirculating to the turbo inlet pipe.
If this is the air metering method in your car and you want the "PSSSHHHH" noise, you would be better off installing an open-element air filter, since it is the airbox on most cars that stifles the blow off noise.
If this does not give you the desired effect, you might try changing your BOV to one of our aftermarket BOV's that is capable of recirculating to the turbo inlet pipe.
20 January 2010, 02:51 PM
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Is t there a simple test to see if it's playing up not.
20 January 2010, 03:10 PM
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If you don't like the taste of a sh*t sandwich, are you going to like a cheese and sh*t sandwich any better?
This is one of the biggest arguments for sticking with the standard dumpvalves, as at least you can be confident that they are calibrated within the correct range. The problem with adjustable aftermarket valves is that there's a tendency on the owner's part to set them too stiff - although the article linked above does give a good explanation of how to set the release pressure correctly.
Where is the maf under the hood on a my00 turbo 2k?
Is t there a simple test to see if it's playing up not.
The only way to be certain whether or not they're good is to test them on a bench airflow rig, although you can get a pretty firm idea from datalogging the car under boost and looking at the sensor's output. By the time they are far enough gone to cause idle stability issues, the response at high airflow levels tends to be all over the place.
Last edited by Splitpin; 20 January 2010 at 03:16 PM.
20 January 2010, 03:13 PM
#13
The MAF is a squarish part of the intake duct. It usually shows up as dud when the car's idling is erratic, although this can also be a dirty throttle sensor.
Last edited by alcazar; 20 January 2010 at 03:15 PM. Reason: To remove test that is not correct.
20 January 2010, 03:26 PM
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What do you mean by "unroll full throttle"? You've missed the point that atmospheric venting is undesirable on a suck-through MAF equipped car, full stop. On that basis, a valve that does recirc part of the time and VTA part of the time is just as undesirable as a pure atmospheric one.
If you don't like the taste of a sh*t sandwich, are you going to like a cheese and sh*t sandwich any better?
That's correct, but the key point to make there is that a properly adjusted dumpvalve (whether VTA or atmos) will not damage the airflow sensor. MAF damage only results when the valve is set too stiff and does not dump, causing compressor stall and resulting in pulses of air travelling backwards through the induction tract.
This is one of the biggest arguments for sticking with the standard dumpvalves, as at least you can be confident that they are calibrated within the correct range. The problem with adjustable aftermarket valves is that there's a tendency on the owner's part to set them too stiff - although the article linked above does give a good explanation of how to set the release pressure correctly.
Sometimes, but more often than not you'd notice it's failing after your on-boost mixtures have been leaning off for some time - with consequent risk of engine damage from the resultant cylinder temp increases and detonation.
Same place it is on all Imprezas - in the pipe immediately after the airbox. If you have an MY00, you'd be even further advised to avoid aftermarket valves, as the 99/00-type MAF is particularly prone to vibration damage of the sort outlined by Doc.
The short answer is no. Someone might pop along later telling you about a test that involves unplugging the sensor with the engine running and seeing if it stalls. Unfortunately that "test" is based on complete bullsh*t and can pass dangerously degraded sensors as "good", so is best avoided.
The only way to be certain whether or not they're good is to test them on a bench airflow rig, although you can get a pretty firm idea from datalogging the car under boost and looking at the sensor's output. By the time they are far enough gone to cause idle stability issues, the response at high airflow levels tends to be all over the place.
If you don't like the taste of a sh*t sandwich, are you going to like a cheese and sh*t sandwich any better?
That's correct, but the key point to make there is that a properly adjusted dumpvalve (whether VTA or atmos) will not damage the airflow sensor. MAF damage only results when the valve is set too stiff and does not dump, causing compressor stall and resulting in pulses of air travelling backwards through the induction tract.
This is one of the biggest arguments for sticking with the standard dumpvalves, as at least you can be confident that they are calibrated within the correct range. The problem with adjustable aftermarket valves is that there's a tendency on the owner's part to set them too stiff - although the article linked above does give a good explanation of how to set the release pressure correctly.
Sometimes, but more often than not you'd notice it's failing after your on-boost mixtures have been leaning off for some time - with consequent risk of engine damage from the resultant cylinder temp increases and detonation.
Same place it is on all Imprezas - in the pipe immediately after the airbox. If you have an MY00, you'd be even further advised to avoid aftermarket valves, as the 99/00-type MAF is particularly prone to vibration damage of the sort outlined by Doc.
The short answer is no. Someone might pop along later telling you about a test that involves unplugging the sensor with the engine running and seeing if it stalls. Unfortunately that "test" is based on complete bullsh*t and can pass dangerously degraded sensors as "good", so is best avoided.
The only way to be certain whether or not they're good is to test them on a bench airflow rig, although you can get a pretty firm idea from datalogging the car under boost and looking at the sensor's output. By the time they are far enough gone to cause idle stability issues, the response at high airflow levels tends to be all over the place.
Srry I'm on an iPhone and the autocorrect is giving me grief.
Unrollis actually untill and mapp is maff.
And cheers for info but I've seen a bov for the scoob that recirc untill about 4k the it's vta are u saying it's bull****.
20 January 2010, 03:39 PM
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And cheers for info but I've seen a bov for the scoob that recirc untill about 4k the it's vta are u saying it's bull****.
Sure, you will get more manifold vacuum if you lift at 6000rpm than at 1000, but the underlying point I was making is that a "multi-mode" valve of this sort is undesirable because, ultimately, it's still an atmospheric valve.
As used in my cheese and sh*t sandwich analogy above, a valve that recirculates at low engine speeds and goes atmospheric further up will confuse your ECU pretty much the same way a pure atmospheric one will. All of this "dual mode" bollocks is ultimately just a way to sell shiny bling tat to people who don't know better.
20 January 2010, 04:16 PM
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20 January 2010, 05:38 PM
#18
So if VTA valves are no good on Scoobies because of the maf does that mean if your using an aftermarket ecu e.g Simtek which isnt using the maf then a VTA will be o.k to use ?
20 January 2010, 07:15 PM
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[quote=RA Dunk;9169641]I would assume so, but then again theres that stupid f,ing chav noise it makes[/quote
people had dumpvalves well before the chav was invented so i dont know why people keep refering them to chavs and i know lots of well off people who have them fitted.
people had dumpvalves well before the chav was invented so i dont know why people keep refering them to chavs and i know lots of well off people who have them fitted.
20 January 2010, 07:38 PM
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[QUOTE=Roger.m.;9169853]Burrbery is associated with them too yet most chavs wear the fake stuff not the real thing it's a fashion thing besides it's only his opinion
20 January 2010, 09:57 PM
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[quote=Roger.m.;9169853]
yea but they all go pshhhhttttt and ya weally need the loudest egzaust to go with it to mint innit! 
21 January 2010, 10:11 AM
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21 January 2010, 10:20 AM
#27
If you don't like the taste of a sh*t sandwich, are you going to like a cheese and sh*t sandwich any better?
IMHO
Recirc if you have a Maf
DV Delete if Mafless
I have Recirc on the MY06 STi nice sound from a samco air box hose/green filter.
I have DV delete on the MY95 STi mafless simtek with huge RCM cone
In both cases the AFR is either calculated or mapped to be expected.
21 January 2010, 10:34 AM
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the word chav as killed everything. Just cos a group of little kn@bs started getting their hands on things deemed as good us normal people get tarnished with the same name for example nike air max classics out before the chav. But theyre the ultimate chav trainers. It goes on and onThey really have ruined everything. I.m going to make my car into the ultimate chav killer dress it as a gl and load it with some sort of laser that teleports the little scroates to a plannet far far away
rant over
rant over
21 January 2010, 05:47 PM
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21 January 2010, 05:57 PM
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