BOV vacuum eh?

Q&A regarding engines, turbos, and intercoolers and power upgrades

BOV vacuum eh?

Postby leekycelicy » Fri Mar 21, 2014 6:35 pm

so I have a large BOV, on my st165, its a t piece between the turbo and the IC,
I have a vacuum connected to the left side of the throttle housing as suggested.

the BOV vents to the air, but many people do have problems because of the air already being metered by the AFM.

1 - I could connect the exit of the BOV so it goes back into the intake before the turbo? so I would still get the BOV "booosh" and the air is still in a closed circuit?

2 - if the air from the BOV is put back into the intake, surely the extra boost your trying to get rid of is still in the system but your not using it, excessive boost still in the system, or is that ok as long as its travelling the correct route through the turbo and not pushing back through the one way system it.

3 - dumping boost back into the turbo, what happens to it? if your not on the throttle it would effectively create a perpetual motion machine, boost, dump, recirculate, boost, dump, recirculate, until you put your foot down and then more air gets put in the system as well as the recirculating boost, to much air? something breaks.

4 - if Toyota never put one on the car, then what's the problem, Toyota must have expected this car to last 200.000 miles and not 20.000 before things brake, like a turbo. if Toyota knew that excesses of boost was trying to get through a closed system they would do something about it.

5 - at the moment my car is building up boost and when the turbo is about to kick in its dumping and stall/goes lumpy for a second or 2 then goes to normal again. but works fine when im stationary, and revving the engine, although its been a while since I have ran it and I may have rectified it now, will drive it tomorrow. thoughts were I had my BOV set up to let go of the boost to soon, well.... way to soon as its not even started boosting yet. BOV, vacuum, leak, etc....

I have put new spark plugs in and this might rectify it, easiest thing first right?
why would shitty spark plugs affect the dumping of boost, or could it be fuel cut because the spark is weak?
I swear the boost dumped first and then cut. maybe wrong, tomorrow will know more
Members don't see the above ad. Register now - it's free!
leekycelicy
Club Member
 
Posts: 92
Joined: Mon Sep 23, 2013 7:17 pm

Re: BOV vacuum eh?

Postby MWP » Mon Mar 24, 2014 9:19 am

leekycelicy wrote:1 - I could connect the exit of the BOV so it goes back into the intake before the turbo? so I would still get the BOV "booosh" and the air is still in a closed circuit?


Yes, do that.
Youll still get some noise, depending on your air filter setup.

2 - if the air from the BOV is put back into the intake, surely the extra boost your trying to get rid of is still in the system but your not using it, excessive boost still in the system, or is that ok as long as its travelling the correct route through the turbo and not pushing back through the one way system it.
3 - dumping boost back into the turbo, what happens to it? if your not on the throttle it would effectively create a perpetual motion machine, boost, dump, recirculate, boost, dump, recirculate, until you put your foot down and then more air gets put in the system as well as the recirculating boost, to much air? something breaks.


The air goes back out the air-filter.

4 - if Toyota never put one on the car, then what's the problem, Toyota must have expected this car to last 200.000 miles and not 20.000 before things brake, like a turbo. if Toyota knew that excesses of boost was trying to get through a closed system they would do something about it.


BOV's were introduced on later models to reduce audible turbo sounds (NVH).
They were never introduced to increase the lifespan of the turbo.
My collection of GT4 documentation: http://gt4.mwp.id.au
Daily: Celica GT4 ST185 (~170kw/atw)
Project: Toyota RA28 '77 Celica (1UZ-FE powered)
Chairman of the SA Classic Celica Club.
MWP
Established Member
 
Posts: 1591
Joined: Mon Jun 01, 2009 11:02 am
Location: Adelaide, South Australia

Re: BOV vacuum eh?

Postby 88gt4DE » Mon Mar 24, 2014 12:17 pm

I run mine on a 165 with a t-hose between turbo and intercooler and vent to atmosphere and I haven't had any problems.
Rob
1988 ST165 - 77K - Project ---> http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=31483&start=240
2000 Toyota Tundra SR5 - 162K - DD - Thanks 97JZA80
2007 Toyota Rav4 - 110K - My girls DD
1999 Honda Civic - 116K - Highway Runner
User avatar
88gt4DE
Established Member
 
Posts: 2665
Joined: Tue Nov 25, 2008 2:44 am
Location: New Castle , DE

Re: BOV vacuum eh?

Postby leekycelicy » Mon Mar 24, 2014 9:20 pm

88gt4DE wrote:I run mine on a 165 with a t-hose between turbo and intercooler and vent to atmosphere and I haven't had any problems.


im not sure if the bov is the problem, it seems to cut fuel before its even built any pressure , mostly in second gear, 1st is a little better.

trying to diagnose, step by step.
leekycelicy
Club Member
 
Posts: 92
Joined: Mon Sep 23, 2013 7:17 pm

Re: BOV vacuum eh?

Postby 88gt4DE » Tue Mar 25, 2014 1:32 am

Last time I had that problem ... fast cut ... the hose going to the turbo housing had fallen off ...
Rob
1988 ST165 - 77K - Project ---> http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=31483&start=240
2000 Toyota Tundra SR5 - 162K - DD - Thanks 97JZA80
2007 Toyota Rav4 - 110K - My girls DD
1999 Honda Civic - 116K - Highway Runner
User avatar
88gt4DE
Established Member
 
Posts: 2665
Joined: Tue Nov 25, 2008 2:44 am
Location: New Castle , DE

Re: BOV vacuum eh?

Postby leekycelicy » Tue Mar 25, 2014 6:16 pm

88gt4DE wrote:Last time I had that problem ... fast cut ... the hose going to the turbo housing had fallen off ...


I have to say I have not inspected that area a lot, might have to take a closer look, cleaned up the distributor not that it was dirty and pushed all the leads back hard etc......... found a leak on a vacuum, replaced, checked a few more hoses, listened for leaks etc........

took it for a drive and did the same thing, get to 3000 rpm and CUT, managed to get it to got up to 4500rpm in first by feathering the throttle and using the gears to rev the engine, but kept stuttering and cutting,.

maybe smelt a little rich when I was pulling away,

next oil change and coolant flush tomorrow, plus intercooler flush. plus turbo area inspect
leekycelicy
Club Member
 
Posts: 92
Joined: Mon Sep 23, 2013 7:17 pm

Re: BOV vacuum eh?

Postby phattyduck » Tue Mar 25, 2014 10:46 pm

You have a large boost leak. Fix it!

-Charlie
'89 Camry LE Alltrac 3S-GTE - SV25/ST205 hybrid
'99 4Runner SR5 4WD 5VZ-FE
Previous: '88 Camry LE Alltrac 3S-GE BEAMS, '90 Camry 3S-GTE, '90 Camry DX
User avatar
phattyduck
Established Member
 
Posts: 1045
Joined: Wed Dec 07, 2005 8:09 am
Location: Pasadena, CA

Re: BOV vacuum eh?

Postby 88gt4DE » Tue Mar 25, 2014 11:34 pm

phattyduck wrote:You have a large boost leak. Fix it!

-Charlie



Yes ... my other suggestion would have been an evap smoke machine to test for leaks ....
Rob
1988 ST165 - 77K - Project ---> http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=31483&start=240
2000 Toyota Tundra SR5 - 162K - DD - Thanks 97JZA80
2007 Toyota Rav4 - 110K - My girls DD
1999 Honda Civic - 116K - Highway Runner
User avatar
88gt4DE
Established Member
 
Posts: 2665
Joined: Tue Nov 25, 2008 2:44 am
Location: New Castle , DE

Re: BOV vacuum eh?

Postby leekycelicy » Wed Mar 26, 2014 9:03 am

88gt4DE wrote:
phattyduck wrote:You have a large boost leak. Fix it!

-Charlie


Yes ... my other suggestion would have been an evap smoke machine to test for leaks ....


I have a party smoke machine, or is that not powerfull enough?

Its fuel cutting in second when i put my foot down it cuts instantly sometimes, no boost build at all just cut.

It revs just fine when stationary and the bov fires as it should, surely if i had a boost leak it would do it when stationary? Its only under load, at 3000 in 1st and randomly in 2nd 3rd
leekycelicy
Club Member
 
Posts: 92
Joined: Mon Sep 23, 2013 7:17 pm

Re: BOV vacuum eh?

Postby 88gt4DE » Wed Mar 26, 2014 12:15 pm

Party smoke machine will work if you can pipe it into the car somehow sure ...
Rob
1988 ST165 - 77K - Project ---> http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=31483&start=240
2000 Toyota Tundra SR5 - 162K - DD - Thanks 97JZA80
2007 Toyota Rav4 - 110K - My girls DD
1999 Honda Civic - 116K - Highway Runner
User avatar
88gt4DE
Established Member
 
Posts: 2665
Joined: Tue Nov 25, 2008 2:44 am
Location: New Castle , DE

Re: BOV vacuum eh?

Postby leekycelicy » Wed Mar 26, 2014 3:42 pm

88gt4DE wrote:Party smoke machine will work if you can pipe it into the car somehow sure ...


I have an air compressor to, I could fire the smoke in and compressed air as well, or I could put the smoke into the intake of the compressor and fill the tank up with Smokey air then put it in through a pipe off the intake near the filter.

car revs and sounds fine bov works etc... but not while driving, I guess the load on the engine of having to move is more and that's when its not liking it.
leekycelicy
Club Member
 
Posts: 92
Joined: Mon Sep 23, 2013 7:17 pm

Re: BOV vacuum eh?

Postby phattyduck » Wed Mar 26, 2014 5:36 pm

You won't get enough boost while free revving to show a boost leak. You probably have a cracked boost hose somewhere, or maybe a missing clamp or something.

Something like this is what you need to do:
http://www.youtube.com/watch?v=atretf9u-Mc

-Charlie
'89 Camry LE Alltrac 3S-GTE - SV25/ST205 hybrid
'99 4Runner SR5 4WD 5VZ-FE
Previous: '88 Camry LE Alltrac 3S-GE BEAMS, '90 Camry 3S-GTE, '90 Camry DX
User avatar
phattyduck
Established Member
 
Posts: 1045
Joined: Wed Dec 07, 2005 8:09 am
Location: Pasadena, CA


Return to Performance and Power

Who is online

Users browsing this forum: No registered users and 1 guest

cron