Secondary air door/A.K.A Flapper door Experiment

[DRS]

^ This is a simple answer actually. The 09-2011 were not GDI engines yet the intake runner is still the same...why retool? They would have to redesign the intake or leave a hole in it when they dont have to. Seems to be a cost cutting measure to me

Good logic. And this "design" is quiet.

 

[DRS]

I agree. I have known about this cavity for some time now. I can't see any down side to drawing air in from this source full time.

Going to see if I can remove the flapper per your documentation this Sunday. And double check the air does come from right behind the headlights and in front of the bracing.

 

[NSXNEXT]

Going to see if I can remove the flapper per your documentation this Sunday. And double check the air does come from right behind the headlights and in front of the bracing.

It's so simple. One hex head screw then just pull the flapper door straight up and out.

 

[daviderle]

Removing the flapper / switching magnets is really not necessary unless one can recreate the dead engine / 2 seconds delay during slow down... As it has been mentioned before, "If it is not broken, no need to fix it"... Just my two cents..

 

[OneFunGenesis]

Removing the flapper / switching magnets is really not necessary unless one can recreate the dead engine / 2 seconds delay during slow down... As it has been mentioned before, "If it is not broken, no need to fix it"... Just my two cents..

This. So much engineering goes into a car that I dont think a weekend warrior can circumvent it :/

 

[amartz]

Why don't they just give the engine all the air it wants? Why have a variable air intake?

Simply, air-fuel mixture ratio. You need to keep the ratio within a range to keep the engine running, or the fire goes out.

 

[sluggo]

Simply, air-fuel mixture ratio. You need to keep the ratio within a range to keep the engine running, or the fire goes out.

I could be wrong, but I'm pretty sure that's what the MAF, temperature sensors, throttle position sensor and fuel injection system are for. The FI system takes all the inputs, figures out the ideal operating mixture and makes it happen it by programmed spray times and durations.

If this intake system is in fact the same one that was used for the older PFI engines, then it looks like they simply programmed the GDI engine for partial manifold vacuum and left it at that. Save further intake system refinements for the follow-on models and get more life out of the existing tooling. Makes sense.

 

[amartz]

You do talk about the throttle position sensor. Maybe I misunderstood, but isn't that what you are advocating removing, the throttle?

 

[sluggo]

You do talk about the throttle position sensor. Maybe I misunderstood, but isn't that what you are advocating removing, the throttle?

Oops. When I refer to the "throttle" in "throttle position sensor", I'm actually referring to the "gas pedal". So I really should say "gas pedal position sensor". Using the terms "throttle" and "gas pedal" interchangeably is a mistake I shouldn't make when talking about fuel injection, intake systems, and drive-by-wire pedals. My bad.

But I'm not really advocating for the removal of anything - the "throttle" (air intake control mechanism) on this engine is already gone.

For most of it's existence (during the period of carburetors and port fuel injection), the "gas pedal" has been not a gas pedal, but an air pedal. The pedal controls how much air is allowed into the engine, and the air flow just sucked the gas along with it. There is no direct control of the gas flow, just the air.

In GDI engines, though, there's no direct control of the air, just fuel. Air flows directly from the outside of the car to the back of intake valves with no metering whatsoever. No other gasoline engine does this.

 

[amartz]

I wouldn't think that moving the injection point from above the intake port to inside the cylinder would change the need for a throttle body. Anybody got a parts diagram that shows this??

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[amartz]

Well, I found these articles for reference:
http://en.wikipedia.org/wiki/Fuel_injection
http://en.wikipedia.org/wiki/Gasoline_direct_injection
http://advtechconsultants.com/GDIEngine.htm

 

[sluggo]

Good references, Amartz. Two key sentences from the wiki article on GDI:

"Engine speed is controlled by the engine control unit/engine management system (EMS), which regulates fuel injection function and ignition timing, instead of having a throttle plate that restricts the incoming air supply. Adding this function to the EMS requires considerable enhancement of its processing and memory, as direct injection plus the engine speed management must have very precise algorithms for good performance and drivability."

(my bolding)

The article also mentions the benefit (with the design-out of the throttle) of the elimination of the pumping losses that occur when an air-throttled engine pulls a hard vacuum on the intake stroke.

 

[amartz]

The sentence I took note of was "That is, there is no air throttle plate eliminating air throttling losses in some GDI engines," (Bolding mine). The Genesis has a throttle body. In at least one msg board I was rambling thru, they observed the throttle plate was there for idle operation only. It'd be interesting to read how Hyundai sees this.

 

[sluggo]

Okay, so this weekend I did what I should have done before speculating/spouting off about the Genesis air intake system. I opened the hood and looked.

Right there, under the cover and near the back of the manifold, is a throttle body.

Oops.

So please forget my earlier questions about why the flapper is needed on a car that's not air-throttled, because the 2013 GDI 3.8 Genesis is indeed air-throttled.

And having a throttle body, with direct control of the air intake, makes the "flapper" inclusion just that much more puzzling. The engine, under idle/no-load conditions, can run extremely lean (as in 65:1), so why restrict air intake under idle conditions?

 

[amartz]

I still liked your question, why do we need a throttle at all? In theory....

 

[amartz]

And having a throttle body, with direct control of the air intake, makes the "flapper" inclusion just that much more puzzling. The engine, under idle/no-load conditions, can run extremely lean (as in 65:1), so why restrict air intake under idle conditions?

At least with the 3.8, if either input can deliver as much air as the engine needs in a no/light-load condition, then I see it as, it's an issue of where are we going to source the air from. Over the radiator, or behind the headlight.

 

[Youseethefight]

The big question I still don't understand is what the secondary air door/ flapper is for?

My results after removing are great. Better throttle response and tons of power from WOT from stop.

Anyone else remove the flapper/ secondary door under the intake?

If so please post your results.

 

[JBoogie]

One thing i haven't seen anyone mention.. Since the amount of air that the computer has learned the car will receive during acceleration will be changed.. Will it be necessary to disconnect the neg batt terminal (usually for about 2 hours) and drive around for a while to let the computer "learn" the new airflow patterns?
I have done this with all the cars i have installed CAI's in.

 

[daviderle]

One thing i haven't seen anyone mention.. Since the amount of air that the computer has learned the car will receive during acceleration will be changed.. Will it be necessary to disconnect the neg batt terminal (usually for about 2 hours) and drive around for a while to let the computer "learn" the new airflow patterns?
I have done this with all the cars i have installed CAI's in.

The answer from what I have seen is yes, unless you would like to wait for 100-200 miles for the ECU to adjust to the new driving conditions..

For anyone who is doing this (tachophile? ), please keep the other thread Poll updated so we can keep track if these intake mod(s) are making a difference in day to day driving conditions.

http://genesisowners.com/hyundai-genesis-forum/showthread.php?t=13828

 

[daviderle]

Ram Air I hope you do not mind...

I am going to copy these responses back to the original thread with the poll so we can keep track of our progress in one thread to minimize any potential confusion.

http://genesisowners.com/hyundai-genesis-forum/showthread.php?t=13828[/QUOTE]

We can keep updating this thread for any theories or technical discussion, but would love to report real world day to day driving impressions / results in the other thread...

Thanks for all feedback, you guys are awesome....