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Discussion Starter · #1 · (Edited)
True story. Mine sucks too.

I've been thinking about this ever since I installed my Injen intake, and WHY we need to reset the battery on some cars to install it "correctly."

Anyone who has used engines made in the past have noticed that there is a screen in front of the MAF. Very few people and even companies realize just how sensitive a device the MAF sensor is and how critical its calibration is. The truth is that they are very sensitive to turbulence.

The stock air box has a restrictive filter and a "hair dryer" vent attached to the end of the tube. That vent is actually an air straightener that reduces turbulence and ensures that there is an even flow of air across the entire area of the tube when it crosses the MAF.

None of the aftermarket intakes have this. I was talking to Trifecta Vince and he notes that K&N now includes an air straightener in the Sonic intake, which means that they also acknowledged the problem. However, that air straightener has to be super glued in. Vince has also expressed frustration over the aftermarket intakes available and how "un-tunable" they are. This is why.

I visited the GM wind tunnel on Thursday and confirmed the importance of this. They have a massive metallic window screen across the entire height and width of the wind tunnel, which is designed to eliminate turbulence.

This morning, I went to my car, and cut a square of window screen that I use for vented sub boxes to keep fiberglass from blowing out. Since the Injen intake is a two-part intake, I took it off, placed the screen over the tube, and placed the coupler over it. I straightened all the edges tight across the intake and tightened the hose clamp down and put it back together.

Went out for a drive and noticed the following.

- more consistent throttle response launching with the 6MT, making it easier to slip the clutch smoothly while taking off from a start.
- smoother power delivery across the entire power band.
- elimination of all power surges I would occasionally get at WOT.

The power increase with the tune at WOT from even 1500RPM is so incredibly smooth and linear that it's crazy. The car now feels like stock, but with more peak power.

I highly recommend that anyone who has an aftermarket intake go out and put a piece of window screen or even a finer screen if you have one over the middle coupler on the Injen or the end of the filter on the K&N. Then, disconnect your battery ground for a minute and reconnect it.

I'll take some pictures when I get a chance so you can see what I did. The whole idea here is to reduce or eliminate turbulence, which the aftermarket intakes have no way to do. The window screen filters that air and creates a more smooth and even airflow through the intake.

Sent from mobile.
 

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I remember hearing of this on the older GM cars. People were taking the honeycomb screens off of their MAFs when they put their intakes on to "remove restriction" and ended up having all kinds of issues.
 

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Discussion Starter · #3 ·
I remember hearing of this on the older GM cars. People were taking the honeycomb screens off of their MAFs when they put their intakes on to "remove restriction" and ended up having all kinds of issues.
Exactly. The problem here is that the MAF "screen" is built into the air box that people are removing. Not good.

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I have a question along the same vein. I had a K&N drop in for a while and I recently(within the last 2 mos) went back to the stock filter. Since it was just a drop in, should I have disconnected my battery. I know it was suggested to do so when installing the Injen as an SRI. I never disconnected the battery but then I retuned 2 weeks ago. Yes my plugs are at .028. I have been considering removing the tune again since I am not all that impressed with it's performance. Any suggestions?
 

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I have a question along the same vein. I had a K&N drop in for a while and I recently(within the last 2 mos) went back to the stock filter. Since it was just a drop in, should I have disconnected my battery. I know it was suggested to do so when installing the Injen as an SRI. I never disconnected the battery but then I retuned 2 weeks ago. Yes my plugs are at .028. I have been considering removing the tune again since I am not all that impressed with it's performance. Any suggestions?
No, a Drop-in does not require this as you are not changing the intake itself, and therefore not changing how air enters the engine.
 

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looking forward to some pics, nice job taking time to do this. will be doing this next weekend
 

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extreme...i agree with you. put the injen has a funny looking pipe welded into it on the inside just before the MAF sensor and that is supposed to stop the turblance. Does it work...sounds like it don't from your testing. But also when under full boost the air bing sucked thru the intake moves so fast it is puul straight no matter what is in the intake. Also the MAF sensor is just about always unpluged when a new intake is installed. By removing the 5v reff the current learned calibration is lost and it needs to relean. That why the car runs a little funny and the cooling fan comes on. Because of the speed of the incomeing air changes so much and so fast cause of the turbo, a normal MAF will not work. When the sensor is pluged back in there is reclarbation that needs to be done. Unless you have the GM gds you can't do it.


maf.gif
 

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Discussion Starter · #10 ·
extreme...i agree with you. put the injen has a funny looking pipe welded into it on the inside just before the MAF sensor and that is supposed to stop the turblance. Does it work...sounds like it don't from your testing. But also when under full boost the air bing sucked thru the intake moves so fast it is puul straight no matter what is in the intake. Also the MAF sensor is just about always unpluged when a new intake is installed. By removing the 5v reff the current learned calibration is lost and it needs to relean. That why the car runs a little funny and the cooling fan comes on. Because of the speed of the incomeing air changes so much and so fast cause of the turbo, a normal MAF will not work. When the sensor is pluged back in there is reclarbation that needs to be done. Unless you have the GM gds you can't do it.


View attachment 44033
I didn't know that the PCM had any current going through the MAF while the engine is off. Strange.

In any case, I didn't know that the Injen has that pipe welded in to reduce turbulence. My impression was that it existed to control the pipe diameter relative to the stock tuning. In any case, I can tell you from personal experience now that it doesn't work very well.

At full boost, we go into open loop mode and the PCM ignores the MAF sensor and refers to fuel trims to determine fueling, so this will only make a difference in your power band at part throttle, closed loop. I did notice I had a slightly smoother idle as a result of this.

My understanding is that the recalibration can also be done by Vince as part of the datalog after you install the tune.
 

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I have been considering removing the tune again since I am not all that impressed with it's performance. Any suggestions?
I have the stock air box with K&N drop in and Trifecta tune. I was pretty impressed today, when I needed to get by some pokey leaf lookers. Outside temp was high 50 degrees and I had apparently (inadvertently) switched to sport mode. Car pulled way better than stock up past 5000 rpms and easily passed going from around 40 to about 75 in third gear.
 

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This is why I sold my Injen intake. Trims were all over the place. And it still pulls under hood air. Went back to stock intake with K&N drop in.
 

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with out starting the engine, pop the hood and unplug any 5v sensor,map,map throttle and open the car door while sensor is unpluged. plug the sensor back in and start the car. you should have a cel on and or a socode set as faild and than passed. for some reason when the bcm is powered up by opening the hood, car door or what ever the pcm comes alive and checkes all 5v sensors. if one is missing, it sets the code. simply disconnecting the the battery will reset this.
 

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I got a C in fluid mechanics
I recall spending many hours with a study team on Fluids - it was a bear.
 

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I have a question along the same vein. I had a K&N drop in for a while and I recently(within the last 2 mos) went back to the stock filter. Since it was just a drop in, should I have disconnected my battery. I know it was suggested to do so when installing the Injen as an SRI. I never disconnected the battery but then I retuned 2 weeks ago. Yes my plugs are at .028. I have been considering removing the tune again since I am not all that impressed with it's performance. Any suggestions?
Live with a stock car because nothing will make you happy seems like lol. I mean this is the second time and your not impressed I love my tune and will never take it off.

Sent From My Galaxy Note 3.
Which is bigger than my hand.
 

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Or just delete the resonator and not have this problem in the first place. I've heard the K&N. It sounds just like a resonator-deleted airbox from inside the car to my ears. The Injen may sound different. But, why pay $200-300 to make no more power and get a sound that could be gotten for free? :icon_scratch:
 

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Interesting:) I wonder if the o.e. "air straightener" can be incorporated into the K&N Cold air intake assy. somehow (it may be a larger diameter tube....the o.e. is removeable...
IMG_20131026_205223.jpg IMG_20131026_205237.jpg
 

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Discussion Starter · #20 ·
Honeycomb Airflow Straightener
Here you go, a little better than window screen.:eek:ccasion14:
Thanks for finding that! I will definitely pick one up for my intake.

Window screen was simply the easiest thing to use and I had it on-hand. Mostly convenience, but those honeycomb air straighteners are a better option.

Sent from mobile.
 
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