Jump to content
SAU Community

Recommended Posts

  • Replies 41
  • Created
  • Last Reply

Top Posters In This Topic

Guest hybrid2nr

The ricers over here still don't understand why atmospherically-vented BOV's on engines with MAF sensors make them give off a puff of black smoke when they lift to shift. They'd rather have that goofy noise than have their engines run correctly. Shows you where their priorities are at.

You would have to assume that people are aware that if the BOV is changed so it vents to atmo there will be problems. This is because when all that air the MAF has just measured which it thinks is being vented into the intake (after the MAF) but isnt will mean there is less air in the system. As a result it dumps enough fuel into the engine for the vented air and the air coming through the MAF ie there is less air than the computer thinks and it gets too much fuel (floods the engine stalling it).

In short dont go the aftermarket BOV unless you can plumb it back. I am making an adaptor for my SSQV to plumb back so i dont look like a twat and have my car stall at the lights.

  • 2 weeks later...

Let me know how it works out, cause I'm thinking of getting one, and wanted to know what they are like from someone who actually has one.

I found out that my stock one is leaking.... I took it off, and blew air into it from the inlet and it just leaked through the other side.

Wierd.

  • 1 year later...

its not MAF cars that run rich/overfuel on shift coz of BOV's, its AFM cars isnt it? MAF = mass air flow like what aftermarket ECU's use which *stop* overfuelling from BOVs.

whereas stock cars have plain hotwire Air Flow Meter which overfuels with the atmo bov.

but yeh the point was right that they cause overfuelling.

its luck of the draw tho how bad or watever depending on many factors.

my DR30 skyline has an old Jap bov of some sort, with it D/C there is noticable lag on shift at 1bar boost pressure. with it reconnected there is noticeabley less lag, even tho its slight and mostly see it on slower shifts.

getting a hybrid 600x300x75 cooler installed over the next 2 days along with a Sard R2D2 BOV, so we'll see how that bad boy goes !

romeo - yeh i think u can get electronic BOVs for non turbo cars but ... please dont. lol its so lame. !

roy - ah right yeah i got confused also. pple interchange the terms too much these days. so AFM = Air Flow Meter which is a Mass Air Flow sensor system, whereas MAP is Mass Air Pressure and is just a MAP sensor and has no other name?

how exactly does the MAP not be interupted by a BOV then? wouldnt the pressure drop wen the bov releases and confuse that too? im totaly unsure of the principle behind the MAP sensor so this may be a stupid suggestion but im sure some1 will clear it up for me!

cheers dudes!

'] wouldnt the pressure drop wen the bov releases and confuse that too?

In a brush stroke explanation , when it senses the drop in manifold pressure it guesses that there is a drop in cfm so drops the duty cycle on injectors, (less fuel injected) so doesnt experience the same dramas as AFM equipped cars.

Is the HKS SSQV plumpback or vent to atmosphere?

T.

Vents to atmoshpere only.

I've got one. When I had the standard intercooler and was running standard boost, I hated the sound of it. Sounded like some puncy little train whistle, or a gay guy on Oxford street checking out my ass...

after increasing the boost, it sounds a lot more aggressive and masculine... makes me feel like all 80kg of masculine rice boy. :cheers:

Nah - they're pretty good but as I say, sounds fairly camp at low boost..

Giles

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Apologies for the long post, but needed somewhere to lay out the entire timeline of events and actions taken:   I've got an 89 GTR with a R34 RB in it. It's been running great all year, driven probably 500KM in the last month. It's not my daily driver, just a weekend fun car.    Build info: R34 RB26 - HKS 2.7 stroker kit, HKS adjustable cam gears, HKS turbo upgrades, Trust intercooler, R34 factory DENSO 440cc injectors, JUN chipped/tuned R32 ECU. All of this work was performed in Japan back in 2019.    Thursday 10/2/25 - It's a nice day and decided I'll drive it to work, I start it up in the garage and I notice it took a few extra cranks and sounded a bit funny. I figure maybe it was just because it was a pretty chilly morning. I pull it out into the driveway to warm up a bit before leaving. As I leave the driveway, it feels very off and sounds like a misfire. I pull it back in the garage to deal with after work and take the daily to work. I was able to diagnose it as a cylinder 5 misfire with the old spark plug test (unplugging each plug until a sound change with the engine running). I take off the whole ignition system, ignitor, plugs, spark. *Important note, it is still on the R32 ignition system with the separate ignitor system. I test each system with a multi-meter and nothing presents as a smoking gun. I put it all back together and it starts up no issue. I go ahead and order the PRP R35 ignition conversion kit. It should arrive today (10/13/25)   Friday 10/3/25 - Another nice day, car starts up great and drives great all day. Very pleased that everything seems to be OK   Sunday 10/5/25 - Decided I'll take it to play some golf, load up and drive to the course about 25 minutes away. Drives wonderful the whole way there, I pull in the parking lot and the engine completely comes to a stop. I do not recall if it sputtered at all, but just remember all of the sudden the engine was off. I roll it into a parking spot, try to crank it back on and nothing.  It'll crank and crank and not even try to start. End up getting it towed back to my house and push it up into the garage.    Items I have checked: Fuel in the tank Fuel Pump relay Fuel pump fuse  Spark Plugs & gap Coil packs Ignitor    I know the cylinders are getting fuel as the plugs smell like fuel after a start attempt. I tried spraying starter fluid into the manifold and cranking and not even a sputter.    I decided to do the live CAS test (removing the the CAS, ignition on and spinning the CAS stalk to see if the injectors pulse and spark is active). All of the injectors were pulsing and I have spark at the plug. The half-moon end of the CAS did seem very loose, I'm not sure how much play is supposed to be there, but it was more than I expected. There was no in/out play of the shaft, just the tip end that is pinned on had quite a bit of play.    CAS Play video   When I put the CAS back in, I stupidly did not re-time the engine. I know I need to do that tonight, however, I do not think it will start given it seemingly was not the issue. My plan is to do the PRP R35 coil kit and retime the engine at the same time.    I plan on ordering the Haltech Nexus Plug-in ECU once they are available again, but ideally would like to get this sorted before firing the parts cannon at it and potentially adding more variables.    Anything glaring that I am missing here, I'm a bit at a loss?          
    • Get it on a dyno. Get something logging Consult. Run it up and find out what is causing it.
    • Looking for a plenum for rb25 de+t neo  Not looking to push much power maybe 300kw at the wheels, is there much difference in flow for Freddy “Greddy style” compared to original Greddy or options like Proflow or Otaku garage?    I won’t be porting the de Neo head for now as I think it’ll be fine 280-300rwkw but appreciate the help and any experiences anyone has between them and any advice. Thanks  Looking at this plenum for now below 
    • engine wise almost no mods: stock ecu Greddy front mount intercooler Greddy forward facing intake w R33 TB stock fuel system, stock injectors, rail etc. Kakimoto racing hyper 3 inch exhaust system Apexi intake filter New NGK –R BCPRES (.8 gap) plugs  
    • Nice one @Pac - looks like a fair few 1600's there! 
×
×
  • Create New...