BOV - The myths and the truths
04-21-2010, 02:24 PM
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BOV - The myths and the truths
Ive tuned a few cars now that run a VTA BOV on their car and there is 0 issue doing so. People like to say it makes the car go rich in between shifts and kills response etc... WELL, after some recent discoveries with DFCO on our cars and logging certain conditions I can tell you that is NOT the case with our cars.
When you do a pull in your car, whether short or long, then release the pedal the car immediately enters DFCO and the AFR goes full lean on decel. SO even if your car dumped fuel into the cylinder like people claim, it will have been "pumped out" on the decel and burned off before you ever noticed it
And it can't effect you doing NLS because the BOV never opens and the AFR remains stable. (From my testing and what I've seen)
If you want a BOV, get it. If that's your thing, enjoy it. My .02. Feel free to discuss
When you do a pull in your car, whether short or long, then release the pedal the car immediately enters DFCO and the AFR goes full lean on decel. SO even if your car dumped fuel into the cylinder like people claim, it will have been "pumped out" on the decel and burned off before you ever noticed it
And it can't effect you doing NLS because the BOV never opens and the AFR remains stable. (From my testing and what I've seen)If you want a BOV, get it. If that's your thing, enjoy it. My .02. Feel free to discuss
04-21-2010, 02:30 PM
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I personally don't have one. But I have tuned a few cars running the HKS, Greddy, Hahn etc.. And a mix of recirc or VTA. Ive seen no drivability issues with any of them. Each did require some spring adjustment to release properly and not back spin the turbo.
04-21-2010, 02:42 PM
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On some older factory cars that had stock recirc bov setups, when you would change them out it did effect the fueling slightly. I never found it to be a major issue but some people are very **** about things. Ive noticed some of that "old" thought being applied to our car and recently I found that it just isn't the same for us. I listed above why that is
04-21-2010, 02:48 PM
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Anytime Ive seen the car boost up and make load, even under light throttle, then you lift it will enter DFCO. Just cruising very lightly then shifting, you are right it will not. BUT the BOV isnt opening creating that old rich condition like other cars.
04-21-2010, 02:54 PM
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If that is the case, then I'd assume that the LNF biases toward the 'VE' side of airflow measurement when in boost. I imagine there is still a rich spike, which probably goes un-noticed by the stock lambda sensor, as DFCO is not an instantaneous transition... there is a delay before switching to make the car more drivable.
04-21-2010, 02:54 PM
#14
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Never seen log of an LNF with a BOV so I cannot comment yet. Jpizzle is suppose to bring me his car in a month or so so I will see then.
04-21-2010, 02:55 PM
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what makes the car pop and gurgle under decel...
i have seen the opposite maybe from improperly setup bov's then i'll have to dig up the logs!
besides the fact they are just plain ghey!
no!!
i have seen the opposite maybe from improperly setup bov's then i'll have to dig up the logs!
besides the fact they are just plain ghey!
no!!
Last edited by 1badBlueberrySC; 04-21-2010 at 02:55 PM. Reason: Automerged Doublepost
04-21-2010, 02:57 PM
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^Preference is a different arguement here LOL. But I agree, Im not a big fan of them anymore!
If you leave that Inj Disable table all stock or the 15's column like mentioned on the HPT site, you will see no change. If you leave it all 0's you will see some adjustments as it opens.
lol!
lol!
Last edited by BYT*SS*TURBO; 04-21-2010 at 02:57 PM. Reason: Automerged Doublepost
04-21-2010, 03:00 PM
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i have logs but used under an old scanner config so nothing shows up as far as fueling i havent tuned the car in over a year since the car is sitting while he is in the virgin islands for work
04-21-2010, 03:00 PM
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I sort of get what you are saying sort of. Makes sense about external BOV's. So DFCO is not the issue and the lean fuel completely burns off after it decelerates.
04-21-2010, 03:11 PM
#20
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99% of the time when you let off to shift or just let off to slow down the ECM tells the injectors to stop spraying fuel and the A/F goes very lean around 19.0-20.0 A/F. As soon as you press the accelerator down the BOV shuts and injectors come back on.
04-21-2010, 03:23 PM
#23
ok after reading this it still does not explain BOVs on the stock tune. Can you run one saftely? In Atmospheric? In Recirc? So basically what your saying is that if you're going to tune anyways, than a MAF relocation is completely pointless in all circumstances?
04-21-2010, 03:32 PM
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I have been running an atmospheric BOV for about a year and 7 months (when i bought the car) and trust me it doesn't do anything bad. I have 40,000 miles to prove it. And i also watch my Aeroforce gauge extensively.