Tial BOV flutter.
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I call them like I see them. I don't have enough disposable income to not follow the advice of certified, tried and tested professionals.
You DO know that recirculating subjects the upper side of the plunger to a vacuum and makes it easier for the BOV to release, Right?
You DO know that recirculating subjects the upper side of the plunger to a vacuum and makes it easier for the BOV to release, Right?
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please do not give out false information's. VTA and the stock EVo MAF set up doesn't work right.
You need to get rid of the MAF to have the VTA bov set up work right .
I dont know who is this guy, but you can ask all respectable tuners and engine builders. They all say the same. I tried the VTA Once in the 4G63T engine and once in the 4B11T. wont work right,.
Now i have VTA , but i have no MAF anymore.
Rob
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Please just stop this nonsense...
Have you tried and tested it yourself? Because I have...
You DO know that there is absolutely no amount of vacuum in the intake tube with that ginormous open hole we call the air filter, Right?
Zero false information here.
Been there, done that...tried and tested on my own car...it works perfectly, absolutely fine.
In case you were wondering how I know: http://www.evoxforums.com/forums/showpost.php?p=965102&postcount=34
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from some tuners for you 
( there is a difference between a MAF and the MAP sensor... )
"For anyone who's wondering why VTA BOVs don't work worth a crap on our cars, our fuel is metered from the MAF. The MAF signal tells the ECU how much air the motor is getting and it uses that to calculate how much fuel it should be putting in. The stock BOV (which is really a compressor bypass valve, not a BOV) recirculates the air back to the intake so the MAF readings are still correct. When you install a VTA valve it lets air out after its been measured by the MAF so the ECU dumps way too much fuel into the motor, which is why it runs like crap."
"concern would be the fact the temp sensor on the maf is now reading charge air temps rather than intake air temps. Charge air temps are a good bit higher than intake temps in most situations."
as you know the ETS guys respond this :
"I wouldn't recommend it. We have had customers have good luck with the 50/50 setup, but the straight VTA seems to always have a problem. I wouldn't recommend it unless running speed density.
Thanks,
Michael"
i am not entirely sure why you think you know better then these guys. Because you tried and you think its working? Some peole actually test and work more cars then one. Others actully even race them, all those do not recomend VTA with MAF sensor in the evo.
Actually i dont really care what you think , i am posting more towards those who try to decide what to do.
Everybody do what ever they want they own car, so i will leave it like that.
Everybody here is an adult and can decide what direction they would like to take.
Cheers Rob
this is my engine bay and i am running MAP sensor that is why i can run VTA. AS you see there is no MAF sensor in the car
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( there is a difference between a MAF and the MAP sensor... )"For anyone who's wondering why VTA BOVs don't work worth a crap on our cars, our fuel is metered from the MAF. The MAF signal tells the ECU how much air the motor is getting and it uses that to calculate how much fuel it should be putting in. The stock BOV (which is really a compressor bypass valve, not a BOV) recirculates the air back to the intake so the MAF readings are still correct. When you install a VTA valve it lets air out after its been measured by the MAF so the ECU dumps way too much fuel into the motor, which is why it runs like crap."
"concern would be the fact the temp sensor on the maf is now reading charge air temps rather than intake air temps. Charge air temps are a good bit higher than intake temps in most situations."
as you know the ETS guys respond this :
"I wouldn't recommend it. We have had customers have good luck with the 50/50 setup, but the straight VTA seems to always have a problem. I wouldn't recommend it unless running speed density.
Thanks,
Michael"
i am not entirely sure why you think you know better then these guys. Because you tried and you think its working? Some peole actually test and work more cars then one. Others actully even race them, all those do not recomend VTA with MAF sensor in the evo.
Actually i dont really care what you think , i am posting more towards those who try to decide what to do.
Everybody do what ever they want they own car, so i will leave it like that.
Everybody here is an adult and can decide what direction they would like to take.
Cheers Rob
this is my engine bay and i am running MAP sensor that is why i can run VTA. AS you see there is no MAF sensor in the car
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Wide open throttle the BOV is NOT working it is suppose to be closed.
The BOV works when you lift throttle, basically releases the extra pressure.
You cant tune cars for BOV valve. That is nonsense.
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So correct me if I misunderstand, but youre essentially saying that a compressor turbine rotating at 100,000 RPM, generating 26lbs of boost... Isnt going to create some sort of vacuum?
Its not a gaping hole. As free flow as cone filters are, they are still restrictive, creating a vacuum.
Its not a gaping hole. As free flow as cone filters are, they are still restrictive, creating a vacuum.
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this is not a pissing match. I dont get angry at all, So i hope that is true for everyone. End of the day we all want the same so yes we need heated debate to get and move forward.
I just share what i think , and if someone can provide me a great fact to make his point valid, i'll take it.
But until , just because "i said", it is not working in my library... LOL
It takes a lot more then that.
ROb
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12,473 Posts
Post that in the other VTA threads. Nobody else is posting logs, just videos that don't prove anything.This is what I see on every VTA to car when tuning and I tuned a lot EVO's... I agree 100% with Robevo
This is a customers car with a VTA BOV...
See what happens when you go into vacuum and the BOV opens to vent...
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I'm quite aware of the differences between a MAF sensor and a MAP sensor. So you do know that our cars have both sensors as a stock setup, correct?from some tuners for you
Well wait a minute...you were the one saying that it goes rich when you're on the throttle...
Now you're changing your story and going with the off throttle rich condition argument? The video absolutely proves that VTA doesn't peg the AFRs rich when you make a pull, which was your original argument...which really never made sense to begin with since the BOV is sealed shut when you're on the throttle.
Is a line across a graph going to show you something completely opposite of what the actual gauge is showing you? Probably not, but my apologies for not getting you a squiggly line...I don't carry my computer and Tactrix cable around with me everywhere I go.
And I'm not really sure what I'm looking at in that log graph...it looks like a big jagged line with one point picked out labeled 10.3 AFR. It doesn't tell me what else is happening with the AFRs throughout the whole graph, it doesn't show how the pull was made...the throttle position is all over the place... and it doesn't tell me what a recirculated valve will do in that exact same situation.
I helped a friend tune his car when he was still learning what all the tables do. He has a recirculated valve. There were several times you could sit there and watch the gauge running 11's, and then he'd let off to shift and it would take a quick stab into the low 10's before getting back on the throttle. So again, showing me one point when a VTA hit 10.3 off throttle isn't proving much...
I'm an open minded guy, and if it was a clear cut WOT, shift, WOT, shift, etc. and it showed AFRs going stupid rich compared to a recirculated valve on an identical pull, then absolutely I'll agree with you 100%. But a few squiggly lines with with no way to read them tells me nothing. The video shows RPM and AFRs, and you can clearly tell it's a WOT pull to redline...and I also posted a part throttle video before, with the gauge immediately swinging more lean during shifts instead of rich...not sure how you can get much more clear than that...
Forgive me, but I'm not the kind of guy that sits here and listens to everyone else and takes it as gospel. If I want to know if something works, I'll go figure it out myself. Just because I don't get paid to tune cars, doesn't mean I don't know how, or how everything works.
Also, I have no disrespect for anyone here, especially Clipse and some of these other guys who have produced some awesome tunes...as far as I'm concerned this is a friendly debate...
...with maybe a few smart ass comments thrown in...my bad..
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I agree no one is arguing here. All I am saying is that with a VTA BOV. During decel/ off the accel pedal the car goes into vacuum.
The simple mechanics/physics show this.
Engine ingest air via the intake which passes by the MAF air is metered.
Let's call this X amount of air.
Now Mr. Joe Rice steps on the accel pedal which in turn goes to boost lets say this is Y. Boost is always positive because it is pressure and not vacuum lets call vacuum Z.
Now when Mr. Joe Rice takes his foot of the accel pedal because a Prius cuts him off...
The engine now ingest X amount of air which has been metered, it goes from positive pressure Y to negative pressure Z. Since it goes negative it means we venting air because inturn this opened the BOV to prevent damage to engine/turbo components.
Y was metered pressure because of the ingested air X which in turn is negative Z.
ECU calculates lets say 50Hz per second how much air it ingested and in turn adds the proper ratio of fuel. If you vent this air and cause negative pressure then the ECU still is adding the same amount of fuel. Why? Because it already calculated how much air it ingested and how much fuel it had to add.
So....
We vented all the metered air the ECU calculated X amount of air into the system and added proper ratio of fuel. If we vent the air out we are left with still the proper ratio of fuel for the metered air, but since there is no air. There is only fuel being injected causing a rich condition.
If the BOV is recirculated it causes less of a rich condition. There is still a very small rich condition because the the injectors never stop injecting after a run but the condition is not as rich.
The simple mechanics/physics show this.
Engine ingest air via the intake which passes by the MAF air is metered.
Let's call this X amount of air.
Now Mr. Joe Rice steps on the accel pedal which in turn goes to boost lets say this is Y. Boost is always positive because it is pressure and not vacuum lets call vacuum Z.
Now when Mr. Joe Rice takes his foot of the accel pedal because a Prius cuts him off...
The engine now ingest X amount of air which has been metered, it goes from positive pressure Y to negative pressure Z. Since it goes negative it means we venting air because inturn this opened the BOV to prevent damage to engine/turbo components.
Y was metered pressure because of the ingested air X which in turn is negative Z.
ECU calculates lets say 50Hz per second how much air it ingested and in turn adds the proper ratio of fuel. If you vent this air and cause negative pressure then the ECU still is adding the same amount of fuel. Why? Because it already calculated how much air it ingested and how much fuel it had to add.
So....
We vented all the metered air the ECU calculated X amount of air into the system and added proper ratio of fuel. If we vent the air out we are left with still the proper ratio of fuel for the metered air, but since there is no air. There is only fuel being injected causing a rich condition.
If the BOV is recirculated it causes less of a rich condition. There is still a very small rich condition because the the injectors never stop injecting after a run but the condition is not as rich.
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I completely understand how this all works...MAF sensor metering air, releasing that metered air through the BOV...I get it.
Almost every other MAF turbo car has that problem.
But...
We also have the MAP sensor, which is the speed density portion of our ECU. The MAP sensor looks at the pressure and temperature of the air to calculate the mass of air flow into the engine. So there's 2 sensors telling the engine how much air is coming in. Tephra has already shown that the engine load follows whichever sensor, MAF or MAP, is reporting the lower load at any given time.
Let's get back with Mr. Joe Rice...he sounds like a cool dude...
Mr. Joe Rice is again making boost with his right foot, MAF sensor is puttin' out some good data for fuel calculations, but the MAP sensor is also seeing absolute pressure (atmospheric + positive boost pressure) inside the manifold, cross referencing that with it's temperature and how fast the engine is turning (RPM) and calculating the mass of air entering the engine, which again, goes into the fuel calculations.
Now our buddy Joe jumps off the gas pedal and the throttle slaps shut, BOV opens and vents some air with that distinctive sound that you either hate or love.
MAF says "I already told the ECU that X amount of air was coming, so send the fuel for X"
MAP says "Hang on, the throttle just slammed shut, and I'm seeing all kinds of vacuum, which means we don't need all that fuel if no air is getting past the closed throttle plate, so I'm telling the ECU to send less fuel"
Now, both sensors send a voltage signal to the ECU. In simple terms, the higher the voltage, the more air that sensor is reporting to the ECU. The more air, the higher the load.
So when the throttle slaps closed and pulls a huge vacuum on the MAP sensor, the voltage is going to immediately drop very low, while the MAF voltage won't drop quite as fast since there is still a bit of air passing through as the turbo spools down.
Less voltage = less load...and we already know the engine load calculated by the ECU follows the lower reported load of the two sensors, in this case, the MAP.
What does all this mean? It means it doesn't matter where you vent your BOV, because when you jump off the throttle and the BOV opens, yes you're venting MAF metered air, but at that point the ECU is fueling the engine off the MAP sensor, meaning that MAF metered air is irrelevant. You're going to run the same off throttle AFR regardless of where the BOV spits out its air.
I have personally seen AFRs during a shift dip a bit rich sometimes, as well as swing leaner with both VTA and recirculated valves. It all depends on how the car is being driven and the situation at hand.
Almost every other MAF turbo car has that problem.
But...
We also have the MAP sensor, which is the speed density portion of our ECU. The MAP sensor looks at the pressure and temperature of the air to calculate the mass of air flow into the engine. So there's 2 sensors telling the engine how much air is coming in. Tephra has already shown that the engine load follows whichever sensor, MAF or MAP, is reporting the lower load at any given time.
Let's get back with Mr. Joe Rice...he sounds like a cool dude...
Mr. Joe Rice is again making boost with his right foot, MAF sensor is puttin' out some good data for fuel calculations, but the MAP sensor is also seeing absolute pressure (atmospheric + positive boost pressure) inside the manifold, cross referencing that with it's temperature and how fast the engine is turning (RPM) and calculating the mass of air entering the engine, which again, goes into the fuel calculations.
Now our buddy Joe jumps off the gas pedal and the throttle slaps shut, BOV opens and vents some air with that distinctive sound that you either hate or love.
MAF says "I already told the ECU that X amount of air was coming, so send the fuel for X"
MAP says "Hang on, the throttle just slammed shut, and I'm seeing all kinds of vacuum, which means we don't need all that fuel if no air is getting past the closed throttle plate, so I'm telling the ECU to send less fuel"
Now, both sensors send a voltage signal to the ECU. In simple terms, the higher the voltage, the more air that sensor is reporting to the ECU. The more air, the higher the load.
So when the throttle slaps closed and pulls a huge vacuum on the MAP sensor, the voltage is going to immediately drop very low, while the MAF voltage won't drop quite as fast since there is still a bit of air passing through as the turbo spools down.
Less voltage = less load...and we already know the engine load calculated by the ECU follows the lower reported load of the two sensors, in this case, the MAP.
What does all this mean? It means it doesn't matter where you vent your BOV, because when you jump off the throttle and the BOV opens, yes you're venting MAF metered air, but at that point the ECU is fueling the engine off the MAP sensor, meaning that MAF metered air is irrelevant. You're going to run the same off throttle AFR regardless of where the BOV spits out its air.
I have personally seen AFRs during a shift dip a bit rich sometimes, as well as swing leaner with both VTA and recirculated valves. It all depends on how the car is being driven and the situation at hand.
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