desperatly need guidance on MAF subject, technically

[giterboosted]

:1zhelp: ok guys, i know weve all read the thousands of posts about the mass air flow and how we gata recirculate or runs rich blah blah blah, i know it will mess us up, thats understood, im jsut racking my brain to really understand the issue. ok i recently purchased the newest version of the HKS SSQV in kit form, i know how to hook it up, anyone who can read can do it, but it wasnt until i really got to looking at the setup that i got to wondering something,

maybe im just not as well versed in this stuff as id like to be but i think i have a general understanding of it. ok the point of the recirculation valve is to release some if not all of the blown off air back into the intake pipe between the maf and the turbo, got that, but i dont get it.

its not in front of the maf so its not to keep it happy, but when it releases the purge if you will its merely blowing it into an unboosting turbo, because (if im wrong someone please correct me) between shifts the turbo is at no boost, so its barely spooling, not enough for the purge back into the intake piping to matter,

i know something im saying isnt rite, it cant be, or else you wouldnt need the recirculation fitting at all,

:1zhelp: basically all i wana know is how the heck this thing helps anything, :1zhelp:

this is my first turbo charged car, let alone my first supra, so please give me some guidance guys, i know most of you have much more experience than me

 

[supraguy@aol]

You want to recirculate because the air has already gone thru the MAF, and the ECU has already sent the signal to the injectors to deliver to proper balance of fuel. If you don't reciculate, then the fuel gets into the cylinders, but the air has left the party early. I assume you're talking about the stock MAF, and not a GM/MAFT retrofit. If you get that setup, then you can use a atmospheric BOV no problem, as long as the MAF is Post turbo. I had mine set up pre turbo for a while(suck thru), then I went to post turbo/IC (blow thru) when I got a Tial-type BOV. Me likes.

Bottom line- Use the recirc if your MAF is stock.

PS- Welcome to the forums man. I'm in Kennesaw, sometimes in Gwinnett. PM me if you have any questions.

 

[giterboosted]

would the lex MAF make a bit of difference in how i vent? i didnt think it would, but i just thought id ask

 

[robbo185]

would the lex MAF make a bit of difference in how i vent? i didnt think it would, but i just thought id ask

lex maf is the same way as stock. It just flows about 25% more air so that way when you upgrade to 550cc injectors (which is about 25%) larger than stock....it balances it out. Running lex afm without either upgraded injectors or a fuel pump and fuel pressure regulator can lead to a running lean condition which is not good.

 

[Motofool]

:1zhelp:

its not in front of the maf so its not to keep it happy, but when it releases the purge if you will its merely blowing it into an unboosting turbo, because (if im wrong someone please correct me) between shifts the turbo is at no boost, so its barely spooling, not enough for the purge back into the intake
this is my first turbo charged car, let alone my first supra, so please give me some guidance guys, i know most of you have much more experience than me

this is not a flame just an informational post for somone wanting to learn more , if you already knew this great if not hopefully somone else will benefit from it.

your turbo never stops boosting it may be slowing down while you shift but the turbo really doesn't change speeds all that fast in off throttle conditions. your wastegate controls the speed at which you increase pressure on the cold side (intake side) but doesn't really regulate how fast it slows down, so its really spinning at almost the same speed and when the gate was fully closed. Remember these things are spinning the 60-80,000 rpms range. a BOV vents pressure for two things so boost doesn't get too high for your motor to handle and to reduce the charge of that pressurized air coming back with closed valves and causing compressor surge. so when you let off the throttle that turbo is still spinning fast enough to keep increasing boost the reason boost is not increasing is the BOV vents pressure so your boost guage drops because there is essentially a large hole in your system dropping the pressure but you are not at zero pressure nor does your turbo stop when you shift.

remember everyone starts somewhere.

 

[TurboStreetCar]

Sorry for the long post, but you seem to be a little confused on the whole process. so its all here.

Actually turbo slows down a good amount on a manual car. if your at WOT (wide open throttle) and let off in a manual car the turbo will be back to just about idle speed within a couple of seconds. because pressure from the outlet of the turbo rushes back into the housing hitting the compressor wheel and slowing/stoping it and possibly if the blow off/recirculation valve isn't working properly reverse the direction of the wheel spinning it backwards. Even a well working blow off/Recirculation wont stop all back flow to the turbo.

The Blow off/recirculation valve helps this by letting that pressure on the outlet side of the turbo out. Its ONLY purpose is the release the charge under Decelleration conditions. It does not regulate boost.

Your boost gauge is plumbed into the manifold side of the throttle body, if it were plumbed in before the throttle body in the intercooler pipes it would not show vacuum(lower pressure then atmosphere for the technically accurate)

The waste gate is plumbed into the intercooler side of the throttle body, it is only exposed to boost pressure. The waste gate is a simple device its a diaphragm with a rod attached to a valve, or a pressure controlled valve. it is referenced to the atmosphere, therefore it will act the same at sea level or at 30,000feet. Pressure builds up into the exhaust housing to spin the turbo, the waste gate bleeds off that pressure to regulate the speed of the turbo.

When you go WOT, the throttle plate opens, 14.7psi, 1 BAR or atmospheric pressure pushes air into the cylinders mixed with appropriate amount of fuel, it is then ignited and pushed out of the exhaust port into the turbine housing of the turbo. The exhaust gasses push on the turbine blades causing the turbine shaft to spin. This spins the compressor wheel witch centrifugally moves air out of the housing towards the throttle body.

When the volume of air the turbo moves exceeds the amount of air the engine can consume, the engine becomes a resistance to flow and causes boost pressure. This pressure moves more air into the cylinder and into the waste gate actuator. As the boost pressure increases the pressure on one side of the waste gate diaphragm increases causing the diaphragm to deflect, opening the waste gate, regulating the pressure in the exhaust housing/manifold to be the right amount of force to spin the turbo fast enough to produce desired boost.

Heres where it comes together, When you shift the throttle body closes, Manifold pressure drops below atmospheric pulling on one side of the blow off valve, boost pressure in the intercooler pipes push on the other, it opens. The waste gate most likely closes because boost pressure in the pipes is drained and thats where its referenced to(though it happens quick so it might only close a little). When you hit the gas again, manifold pressure matches intercooler pipe pressure, both sides of the blow off valve are equal pressure, so the spring closes it, boost pressure rises causing the waste gate to regulate the pressure in the exhaust housing witch regulates the speed of the turbo based upon desired boost pressure.

When the blow off valve opens and drains pressure from the intercooler pipes, that air has already passed threw the Air Flow Meter, so the TCCS already put in fuel for this air. Since this air is not entering the combustion chamber it needs to be recycled to use for next time with that extra fuel. By recirculating it after/post the AFM, the AFM shows a signal of very little flow due to the volume of air displacing incoming air, pulling fuel for that moment that the air is vented from the system regaining the proper air/fuel ratio.

When the throttle plate is reopened, or after a split second where the engine consumes that air again, the Air Flow Meter regains metering the usual volume of airflow while keeping the air fuel ratio always where it wants.

Welcome to the forums. Dont hesitate to ask for help, its what the forums for. Theres alot of technical aspects of turbo cars and how things work, trust me and learn them in the beginning or you'll be REALLY confused later.

 

[supraguy@aol]

...When the blow off valve opens and drains pressure from the intercooler pipes, that air has already passed threw the Air Flow Meter, so the TCCS already put in fuel for this air. Since this air in not entering the combustion chamber it needs to be recycled to use for next time with that extra fuel. By recirculating it after the AFM, the AFM shows a signal of very little flow due to the volume of air displacing incoming air, pulling fuel for that moment that the air is vented from the system regaining the proper air/fuel ratio...

Yeah, what I said.

:naughty:

 

[TurboStreetCar]

yea i know, i just wanted to cover the whole topic from start to finish so there were no empty blanks.

 

[giterboosted]

thank you guys so very much, its been really bothering me,
not that itl make a freakin bit of difference cus ima do what the instructions say either way, but its been really bothering me so bad, cus i just really didnt understand how it could make THAT big of a diff, i understood that there wasnt enough air for that much fuel i just didnt understand how the air that got recirculated got to the fuel to correct sed problems,

ok one more question, i have a venom 400 control module, its basically an on off switch to another fuel air program for the supra, it has a wire going to the maf and one to the tps, will it mess it up if i go with a gm maf, or would it possibly be able to correc the fuel and air problem, i didnt think it would because its not really a computer prob, more of a physical one, but i was jw cus i really wana do the gm maf as a blow thru, but idk if i can use my venom 400,

and do i need to tune a maft at all?

 

[Wills7MGTE]

My MAF died I got a brand new one for 291.00 just sharing I know it doesn't apply. I have an HKS SSQV unrecirculated but since my 90's an auto it doesnt affect it at all, SO TAKE THAT BIOTCH!!!! LMAO

 

[supraguy@aol]

I don't know what that Venom thing does, except maybe fool the ecu into thinking it needs to leave fuel enrichment on. Do you remember if you had to connect it to the cold start switch? Anyway, Go with a MAFT, and you can blow the HKS open air, and you'll have a bit of TPS position- and wide open throttle- type fuel tuning available to you.

 

[giterboosted]

i havent connected it yet, it had a partially blown head gasket when i bought it, and recently it completely blew, so i havent bothered to hook it up, but it also hooks up to the ecu, my brother had one in his 91 talon tsi and it made a HUGE difference, i mean you could feel it like mad,

if youd like to learn more about them please look em up on yahoo
venom 400 performance control module
(please do so you can give me a lil guidance lol)

but do you still hook up the stock wiring to the gm maf? or does the maft have its own plug that goes strait into the maf, and if the venom 400 controls my fuel and such, will it affect anything to have the maft?

btw thanks so much guys, this is the first forum ive been a part of where my posts have acutlly recieved replys and you guys are life savers

 

[TurboStreetCar]

I personally would not use the venom module, it cant be doing anything good enough to spend time working on it.

If you get the maft Gen2, witch i have, is a very nice tuning device that allows a few different MAF sensors to be used. also tunable with 3 different load maps and 14 different RPM points in each map. This is in addition to mainscale for injector sizing and maf sensor tune to change that actual conversion rate from the MAF.

 

[supraguy@aol]

Yeah, I'd like to upgrade to the Gen II eventually.

 

[TurboStreetCar]

I love it, but i really want to go mega squirt 'N spark bad.

The air fuel ratio tracking on the GEN 2 is pretty nice too, tunes itself when hooked up. i just gota hook it up lol

 

[TheNewRed]

My MAF died I got a brand new one for 291.00 just sharing I know it doesn't apply. I have an HKS SSQV unrecirculated but since my 90's an auto it doesnt affect it at all, SO TAKE THAT BIOTCH!!!! LMAO

RECIRCULATING IS NOT A BAD THING, it actually helps alot more on any turbo car b/c instead of just wasting that much air that your turbo worked on getting into the system, it throws it right back into the turbo feed, which in my opinion would be more affective in keeping the turbo spooled between shifts.:naughty:

 

[cuel]

Looks like the Venom module does basically the same thing as the MAFT GenII, but no where near as well. You'll need a map sensor to run either one. I'd go with the Maft, as it has more tuning capabilities.