Supra Forums banner

1 - 18 of 18 Posts

·
Registered
Joined
·
23 Posts
Discussion Starter #1
Hi all,

Just got a bit of work done to my supra, 3" dp and manual boost controller. Works awesome, except when cold. When the engine is cold (running for five minutes or so) and I FT it, it boosts, but all the boost goes out the BOV (have it output to atmosphere so I can hear it well). Its strange. Once the engine is at operating temperature, this problem doesn't exist. When its still cold if I gradually get on the trottle its still there, but not quite as bad. For some reason it just blows off everything while the engine is still cold.

Anyone ever experience anything like this or have any ideas of things I could try to determine problem?

Thanks
 

·
Registered
Joined
·
208 Posts
Well, I'd wait for others to reply since I'm not so experienced with this... but to me it just sounds like it's worn out. I don't know if having it put back the wrong way would give you the symptoms your having. Plus I doubt you put it in wrong. Did you connect that little vacuum hose to the top of the BOV? I don't know if that would cause your symptoms either, but I know that thing is important for opening the vavle at proper times. But yeah if all is well it just sounds like you need to upgrade your BOV
 

·
Registered
Joined
·
527 Posts
yea the problem is you venting the stock bov to atmosphere...thats a no no.....also its probobly shot if its leaking the whole time...id look into finding a replacement....
 

·
slowly giving up...
Joined
·
1,069 Posts
don't boost when the motor's cold. it's not good for it anyway. :)

and don't vent the stock BPV to the atmosphere. it's designed to fluctuate between open and closed. when you vent it to the atmosphere, you constantly lose metered air.

-shaeff
 

·
Registered
Joined
·
23 Posts
Discussion Starter #9
thanks guys, I'll go back to the original bypass configuration, let it warm up and see how it acts this time. pretty use to the hiss now, might have to invest in a real BOV
 

·
Always playing catch up
Joined
·
1,632 Posts
shaeff said:
don't boost when the motor's cold. it's not good for it anyway. :)

and don't vent the stock BPV to the atmosphere. it's designed to fluctuate between open and closed. when you vent it to the atmosphere, you constantly lose metered air.

-shaeff
that also true for the common upgrades? (porche, saab, etx)

if so i gotta get a bov

<l><l>
 

·
Registered
Joined
·
79 Posts
Johnny87 said:
thanks guys, I'll go back to the original bypass configuration, let it warm up and see how it acts this time. pretty use to the hiss now, might have to invest in a real BOV
Venting to atmosphere is a no-no even with an aftermarket BOV. I wouldn't do it unless you get a whole new engine management system and get rid of the stock ECU.

The Supra ECU expects the air to be recirculated. If it's not, you'll run rich everytime you vent to the atmosphere. This is not the end of the world as it's usually only while shifting gears, but it's not the best scenario either.

With an aftermarket air filter you should hear the stock bypass valve or aftermarket BOV even if they're hooked up to recirculate.

Cheers
 

·
Be original, not a copy
Joined
·
861 Posts
The stock bypass valve is just that---a BYPASS valve. It bypasses air around the turbo for a slight increase in fuel economy (air goes from the turbo inlet, through the bypass valve and into the 3000 pipe. It has the side benefit of relieving excess boost pressure in the intercooler system when the throttle is closed. Whenever the motor is not in boost the valve is open--it is a simple diaphram valve and whenever vacuum is applied it opens. Venting the stock bypass valve to atmosphere does nothing but provide a tremendous vacuum leak to the motor. You CAN vent aftermarket blow off valves to the atmosphere because they are designed to open ONLY when vacuum is applied to the nipple and there is boost on the backside of the valve (intercooler piping). Some have had stall issues when venting aftermarket BOVs to atmosphere but if they are adjusted properly and your car is in somewhat of a decent tune then there should be no problem. As a side note there is zero performance gain with a BOV or bypass valve. They are designed to prevent turbo surging so they can definitely improve turbo life but again, they do nothing to increase performance. Also, venting to atmosphere does not change the response time or performance either.
 

·
Always playing catch up
Joined
·
1,632 Posts
edit: ^^^what he said

<l><l>
 

·
Be original, not a copy
Joined
·
861 Posts
Katy eh? I was in Houston for 17 years--will be moving to Copper Canyon in a few years (just outside of Dallas). Still have family in Houston, San Antonio, Humble and Crosby. How is Katy now? It was almost all suburban when I left back in 85. Can't wait to get back to TX though.
 

·
Registered
Joined
·
527 Posts
Shuque said:
Venting to atmosphere is a no-no even with an aftermarket BOV. I wouldn't do it unless you get a whole new engine management system and get rid of the stock ECU.
im sorry but thats not true
 

·
Registered
Joined
·
79 Posts
DeanMarcum said:
The stock bypass valve is just that---a BYPASS valve. It bypasses air around the turbo for a slight increase in fuel economy (air goes from the turbo inlet, through the bypass valve and into the 3000 pipe. It has the side benefit of relieving excess boost pressure in the intercooler system when the throttle is closed. Whenever the motor is not in boost the valve is open--it is a simple diaphram valve and whenever vacuum is applied it opens. Venting the stock bypass valve to atmosphere does nothing but provide a tremendous vacuum leak to the motor. You CAN vent aftermarket blow off valves to the atmosphere because they are designed to open ONLY when vacuum is applied to the nipple and there is boost on the backside of the valve (intercooler piping). Some have had stall issues when venting aftermarket BOVs to atmosphere but if they are adjusted properly and your car is in somewhat of a decent tune then there should be no problem. As a side note there is zero performance gain with a BOV or bypass valve. They are designed to prevent turbo surging so they can definitely improve turbo life but again, they do nothing to increase performance. Also, venting to atmosphere does not change the response time or performance either.
I guess you learn something every day. I never knew the Bypass valve lets air go from the inlet to the 3000 pipe. I thought it only allowed air to travel in the other direction (to prevent surge when the throttle body closed).

Also, it seems others managed venting to atmosphere with an aftermarket BOV (robbo185) and stock ECU successfully. Not sure how they can avoid running rich as air will run through the AFM and not make it to the engine (while the ECU expects it) but I don't want to prevent anyone from trying it. Personally, I wouldn't do it, but if you can do it successfully... Why not?
 

·
Registered
Joined
·
527 Posts
Shuque said:
Also, it seems others managed venting to atmosphere with an aftermarket BOV (robbo185) and stock ECU successfully. Not sure how they can avoid running rich as air will run through the AFM and not make it to the engine (while the ECU expects it) but I don't want to prevent anyone from trying it. Personally, I wouldn't do it, but if you can do it successfully... Why not?
i shouldve explained myself. If you have an aftermarket blowoff valve that can be adjusted its all a matter of tuning it. You will still run rich between shifts...but you car will not stall. Also you dont need a standalone to correct that....a simple AFM to MAFT (in blow through) will fix that
 

·
slowly giving up...
Joined
·
1,069 Posts
why not just keep it recirculated, and get the best performance out of it and your motor? ;)

-shaeff
 
1 - 18 of 18 Posts
Top