Does the CX-7 run a MAF?

[Steiner]

Like the title says, does the CX-7 ECU use a mass air flow sensor? If so I'm wondering how the hec and why the hec people are even considering a VTA blow off valve.

 

[spike blue]

good question!!!

 

[terbow]

Maf

 

[1Sleepy93]

Yes it runs a MAF. I don't plan on running VTA ever.

 

[Steiner]

Thanks for the info guys. There goes my wife's dreams of pshhhhhh pshhhhh pshhhhhhh. LOL.

 

[CX7TT]

it runs on MAF, but I am VTA my HKS BOV, no problem, its been closed to a month now!

 

[xavier]

it runs on MAF, but I am VTA my HKS BOV, no problem, its been closed to a month now!

Do you have any other mods? or do you just have a cold air and blow off? also, does the cold air intake relocate the MAF?

 

[hectik1]

CX7 has a MAF.

VTA can work with the HKS or the Greddy BOV. These don't leak vacuum due to their design.

Other BOVs may not work. Leaking vacuum will cause hesistation due to increased rich conditions.

For Steiner, if your wife wants that sound either A. remove the silencer in the airbox or B. get an intake.

 

[9Hooker]

VTA is a BAD idea in MAF systems.

The air goes by the MAF, thus metering the amount of fuel to add to that gives air. When the BOV activates, it releases air that has already been metered and fuel is dumped in with the system thinking that air is still in the intake tract somewhere. Even though it will run EXTREMELY rich for a very small amount of time it's still not good.

 

[Unit 91]

VTA is a BAD idea in MAF systems.

The air goes by the MAF, thus metering the amount of fuel to add to that gives air. When the BOV activates, it releases air that has already been metered and fuel is dumped in with the system thinking that air is still in the intake tract somewhere. Even though it will run EXTREMELY rich for a very small amount of time it's still not good.

Total facts. You can do it, but it's not the right way.

 

[Silver Ecstasy]

What's VTA? Sorry for the ignorance. I'm trying to absorb as much info as possible.

 

[terbow]

VTA is an acronym for vent to atmosphere (ie. instead of recirculating the air back into the intake, it vents it off)

 

[Silver Ecstasy]

So it's not a good idea to run aftermarket BOV's?

 

[1Sleepy93]

No one said it wasn't a good idea, just not the best to run them VTA. If you run them in recirc it's all good.

 

[9Hooker]

exactly. with MAF (mass airflow) systems, since the air is metered, it has to go in the motor at some time because the computer has scheduled fuel to go with that particular body of air. you can run an aftermarket blow off valve, only the "blow off" has to be piped back into the system SOMEWHERE after the MAF sensor and BEFORE the motor

hope that helps.

 

[Silver Ecstasy]

Eh, my newbness is coming out again.

A BOV is to release excess boost on off-throttle situations. The one that comes on the car OEM doesn't release excess pressure, it recirculates it?

The more info the better guys, again I apologize for not understanding.

Alls i'm understanding is, you wouldn't get the "whoosh" sound.

 

[9Hooker]

Eh, my newbness is coming out again.

A BOV is to release excess boost on off-throttle situations. The one that comes on the car OEM doesn't release excess pressure, it recirculates it?

The more info the better guys, again I apologize for not understanding.

Alls i'm understanding is, you wouldn't get the "whoosh" sound.

here's a rambling...

The BOV releases pressure at a point (yes, at abrupt off throttle excursions to prevent damage to the impeller by the resulting shock wave and keep the turbo spooled up for the same reason) AFTER it has been compressed, and in cars with a MAF, it recirculates it to a part of the intake that has yet to be compressed by the turbo.

so yes, in a MAF system, it has to be recirculated, in a MAP (manifold absolute pressure) system, it can be vented overboard, used to heat the coffee mug in the cabin, blown into your hair, whatever. It doesn't matter since fuel is metered by pressure in the manifold just before being shoved int he motor and not volume at some other point in the system. This is also the reason that fuel tuning a MAF car can yield nice results in an otherwise stock application. The stock computer doesn't take temperature or pressure (density) into account when metering fuel. It the air gets colder and more dense the MAF system doesn't compensate. It throws the same amount of fuel in @ 200 degrees manifold temperature that it does @ 100 degrees. Following PV=nRT and changing the temperature only, you are changing the amount of air molecules being shoved in the motor (the "n" in the equation). The MAF system is oblivious to this. It IS however the cheapest system to design and make fuel maps for. That being said... if you tune your car using some sort of fuel corrections in Tijuana @ 120 degrees ambient and you take the car to Montana where it's 27 degrees ambient you will run extremely lean. Reverse it and you will run rich. So in a MAF system, TUNE to your climate. If it changes, retune!


/rant

 

[Silver Ecstasy]

Meh, well Michigan weather changes everyday so I won't even bother with a daily driver.

But I guess my question lies, how do you recirculate the air off of the BOV? Like for example, someone installed the HKS BOV. It looked like it was out in the open, releasing pressure. How was that recirculating in the air system?

 

[9Hooker]

The discharge port of the BOV, where the blue ring is in the pic should have a rubber hose over it that attaches to the intake piping somewhere from the MAF sensor to the compressor wheel of the turbo.

 

[Silver Ecstasy]

Hmm, I could be wrong, but I didn't see anything. I just seen the BOV attached to a flange of some sort and that was it..no re-routing of any hose to the intake. And where would you even install that on the intake?

(Also, has anyone tried installing a boost gauge on a CX yet, to see what exact boost numbers its getting?)