Hey all. I have fitted a manual boost bleed 'T' to up the boost on my Legnum and have noticed when under hard acceleration the boost rises to about 14psi then starts rapidly dropping to around 8 or 9. Is it normal for these to drop off like that or do I have problems???
Boost dropping/bleeding
- Thread starter Haggiss
- Start date
leebutts
1 AYC Bar
Hi,
do you have stock exaust and piping? It could be dropping due to restriction. Dropping that low does seem a bit unusual however.
Also, the stock BOV's 'allegedly' leak as they get old, you could try replacing it with metal aftermarket or Evo one.
cheers
Lee
do you have stock exaust and piping? It could be dropping due to restriction. Dropping that low does seem a bit unusual however.
Also, the stock BOV's 'allegedly' leak as they get old, you could try replacing it with metal aftermarket or Evo one.
cheers
Lee
- Thread starter
- #4
Thanks for the replies.
I have a Blitz pod filter (I know most you guys dont like them) and a 2 1/2ish" cat back exhaust. Other than that, stock cooler, piping and BOV. Ill do some more investigating!
Thanks again
I have a Blitz pod filter (I know most you guys dont like them) and a 2 1/2ish" cat back exhaust. Other than that, stock cooler, piping and BOV. Ill do some more investigating!
Thanks again
G
Guest
Unregistered
I know it sounds silly, but is the boost controller actually wound up above standard pressure/tension? What I'm thinking is, you *could* have boost spike, then the boost settles back down to STANDARD boost levels.
If you remove the bleed T does it still have this spike in boost? Also, is this in one gear only or all gears?
If you remove the bleed T does it still have this spike in boost? Also, is this in one gear only or all gears?
Mortz
Leaving Skid Marks
It's not that we don't like them, it's just that they don't work well with the VR-4's airflow meter. The air swirls instead of goes straight so it confuses the car basically.
Go and get a HKS/K+N etc etc panel filter and use it in the stock airbox, mightn't totally fix the problem but i'm almost positive you'll hold boost better. A second hand EVO recirculating BOV may also help hold boost better if the old one is leaking.
Go and get a HKS/K+N etc etc panel filter and use it in the stock airbox, mightn't totally fix the problem but i'm almost positive you'll hold boost better. A second hand EVO recirculating BOV may also help hold boost better if the old one is leaking.
- Thread starter
- #8
I assume its wound up as far as possible as it hits boost cut if I click it any further. But then I guess a spike will still induce a cut???
Ill check if it still does it without the 'T'
It also does it in all gears.
and I don't have a standard airbox, my car came from Japan with the Blitz pod
Ill check if it still does it without the 'T'
It also does it in all gears.
and I don't have a standard airbox, my car came from Japan with the Blitz pod
Mortz
Leaving Skid Marks
Should be able to pick one up on here, or trademe.com.nz or ebay pretty cheap. And if you do get the stock airbox back (and you should 
) make sure you get the plastic part that sucks the air in as well.
) make sure you get the plastic part that sucks the air in as well.
G
Guest
Unregistered
You might want to pop your head under the passenger side and rule out that this isn't happening too:
http://ozvr4.com/forums/showthread.php?t=6853
http://ozvr4.com/forums/showthread.php?t=6853
- Thread starter
- #11
Thanks for the info! but i just checked all my pipes and they look fine. Next on the diagnosis list will be removing the boost T and checking what happens. and maybe BOV.
What sort of BOV is recommended for our cars? I have tried a big porn star open one but my car didn't idle with it on. My business is a Turbosmart dealer (shameless plug) so I could get a cheap one from them. Obviously plumb back is ideal for drivability and performance but would one of those combo ones work ok on our cars??? (plumb back and open to atmosphere)
What would cause a boost spike?
G
Guest
Unregistered
Evo IX MR recirculating metal-bodied BOVs are a safe bet, see this thread for pics & more info:
http://ozvr4.com/forums/showthread.php?t=3475
http://ozvr4.com/forums/showthread.php?t=3475
- Thread starter
- #13
Ok.
With the boost T fitted the boost races around to 14 then drops off at 5000rpm to 9psi. It seems to intermittently creep up 1 or 2psi after 5000rpm before trailing back as you would expect at high revs
Without the boost T fitted I get about 10psi which creeps down to 9ish and seems to sometimes hover between the two.
So really, with my Turbosmart manual boost T, im only getting my desired boost for 1000-1500rpm!?
This doesn't sound normal. Im so confused...
With the boost T fitted the boost races around to 14 then drops off at 5000rpm to 9psi. It seems to intermittently creep up 1 or 2psi after 5000rpm before trailing back as you would expect at high revs
Without the boost T fitted I get about 10psi which creeps down to 9ish and seems to sometimes hover between the two.
So really, with my Turbosmart manual boost T, im only getting my desired boost for 1000-1500rpm!?
This doesn't sound normal. Im so confused...
