AIRRAID Intake Tube

[gathermewool]

Originally Posted By: 05Blazer
From Trusted GM employee at the assembley plan:

You don't need a tune with a cold air intake. The internet forums are wrong. The air still passes thru the MAF sensor and that tells the engine how much air is coming in. The baffles are for noise cancellation purposes.


Sorry, but your buddy is 100% wrong on this front. The Mass Airflow sensor is scaled and its values entered into your ECU's memory (it's essentially a lookup table.) If you change the diameter or geometry of your intake, then a larger amount of air could be sucked past the MAF sensor without the MAF sensor actually accounting for it all, since less air would flow past the sensor for the same overall volume.

In this case, the FEEDBACK would be via the ECU reading the discrepancy in the O2 sensor reading from what it what it looked up in that cells respective fueling table and adding or subtracting fuel as necessary. Even if your fuel trims are stored in memory doesn't mean that there won't be times when your ECU can't account for the discrepancy in what tube the MAF sensor was scaled to work with and what you installed. You must either rescale your MAF to work with the new intake or rely upon the ECU to adjust your fuel trim.

Again, the MAF sensor will not account for a change in your intake. The ECU will receive a lean reading from the O2 sensor and adjust your fuel trim after the fact. I'm sure every vehicle is different, but this is how my Subie operates, and this is how I believe all MAF-based fueling systems operate.

 

[SteveSRT8]

Thank God Subaru is not under my hood.

ALL air in the Silverado intake flows THROUGH the MAF.

Unless you have a hole somewhere, you are incorrect.

Wildly platform specific stuff, as the MAF (in this truck) can account for a huge percentage beyond what is actually used in normal operation.

 

[440Magnum]

Originally Posted By: 05Blazer
From Trusted GM employee at the assembley plan:

You don't need a tune with a cold air intake. The internet forums are wrong. The air still passes thru the MAF sensor and that tells the engine how much air is coming in. The baffles are for noise cancellation purposes.



Ding! Thank you.

Lots of people talk like its easy to fool a MAF. But in my opinion UNLESS you modify or damage the MAF housing itself or any airflow collimators that are part of it, and as long as you don't introduce a leak between the MAF and the engine, the MAF will faithfully measure the grams of air per second entering the engine. Its speed/density systems that I think are easier to fool, because they are inferring mass flow from manifold absolute pressure and throttle position, rather than measuring mass flow directly.

JMHO.

 

[440Magnum]

Originally Posted By: gathermewool

Again, the MAF sensor will not account for a change in your intake.



Unless you're talking about something unique to Scooby-doos that I don't know about, I don't see how that's possible. The MAF systems I've looked at (mostly GM), flow ALL the intake air through the MAF. The MAF is an inlne module, and tubing leading to or from it can be any diameter in the world, and still not affect the fixed, calibrated cross section of the MAF sensor itself. Now SOME CAI systems replace the MAF sensor with one that has a bigger cross-section to allow even more flow, and then all bets are off unless that particular MAF sensor is compensated just right to give the same voltage for the same mass flow as the original.

But that's not what the OP is talking about- he left the factory MAF in line.

 

[gathermewool]

I'm not sure why I'm not conveying my thoughts correctly, but I'll try again:

The MAF sensor will sense what flows past it - do we agree on this?

If the MAF sensor is removed from the OEM intake tract of X diameter and Y geometric configuration (the same configuration with which it was originally calibrated) and then installed in an aftermarket intake tract of Y diameter Z geometric configuration, then the MAF sensor will no longer be calibrated correctly and needs to be re-scaled for the change in diameter and geometric configuration.

I'll try putting it another way:

If you have a 2" diameter section of intake tract in which the MAF is installed, the flow rate, in grams per second, will be sensed based on the overall flowrate through that 2" section of intake tract. The MAF sensor doesn't actually measure the EXACT flow rate (in grams/second) flowing past it, but what it does measure is converted by the ECU from a scaling table (calibrated using the OEM intake tract, mind you) into an actual mass air flow rate that can be used in conjunction with the fueling tables to maintain the required AFR.

For the same exact engine load and actual flow rate (in grams/second,) a MAF installed in an intake tract with a 3" diameter, but scaled to a 2" diameter, will read differently, right? I mean, not ALL of the air in the intake tract is funneled through the MAF sensor - the MAF sensor sticks into the intake tract and "samples" the flowrate past it.

 

[SteveSRT8]

^^^I can only speak to GM V8's as we use in our fleet trucks.

Your last line is in error. The GM MAF is a complete unit sealed into the intake, all air goes through it. It is easily able to handle a ton of upgrades with simple tuning, and it will adjust to virtually any normal bolt on modification such as a CAI, headers, etc.

 

[Jim Allen]

Originally Posted By: gathermewool
I'm not sure why I'm not conveying my thoughts correctly, but I'll try again:

The MAF sensor will sense what flows past it - do we agree on this?

If the MAF sensor is removed from the OEM intake tract of X diameter and Y geometric configuration (the same configuration with which it was originally calibrated) and then installed in an aftermarket intake tract of Y diameter Z geometric configuration, then the MAF sensor will no longer be calibrated correctly and needs to be re-scaled for the change in diameter and geometric configuration.

I'll try putting it another way:

If you have a 2" diameter section of intake tract in which the MAF is installed, the flow rate, in grams per second, will be sensed based on the overall flowrate through that 2" section of intake tract. The MAF sensor doesn't actually measure the EXACT flow rate (in grams/second) flowing past it, but what it does measure is converted by the ECU from a scaling table (calibrated using the OEM intake tract, mind you) into an actual mass air flow rate that can be used in conjunction with the fueling tables to maintain the required AFR.

For the same exact engine load and actual flow rate (in grams/second,) a MAF installed in an intake tract with a 3" diameter, but scaled to a 2" diameter, will read differently, right? I mean, not ALL of the air in the intake tract is funneled through the MAF sensor - the MAF sensor sticks into the intake tract and "samples" the flowrate past it.


Wool, you are exactly right.

What you say is almost exactly as John Concialdi, Chief Engineer and owner at AEM explained it to me. How the air flows past the MAF is just as important as how much air flows past it. With a MAF system, the primary way they get power from a CAI is by changing how the air goes past the sensor to fool the MAF into reading differently.

When I got the AEM for my F150, I learned (the hard way) that because of different factory tunes between '04-05.5 and '05.5 and up 5.4L, AEM had to develop two systems. They accidentally sent me the early system for my late '05 and I kept getting lean codes, detonation and other weird things. When I got the right system, only one part of the kit was different, the section of tube in which the MAF attaches, and you could see the difference in the tube and placement of the sensor.

Also, I learned that if you run a CAI designed for a stock-tuned engine on an engine with an aftermarket tune, you may need what they call an offset... which is a specially modified tune that compensates for the mismatch. Most canned aftermarket tunes also lean out the mixture to make power at WOT so if you combine two products that lean WOT mixture, you end up with potentially engine-lethal conditions.

So, the bottom line, as I understand it, is that anything which changes the airflow characteristics on a MAF system can potentially change the way the system operates but you may not notice anything in everyday driving. During closed loop operation, generally speaking, the system will usually compensate for whatever changes occur because the O2 sensors are trimming the fuel. The system may pop a code because it isn't seeing MAF readings where it thinks they should be in relation to the O2 sensor tables. Disconnecting the battery when you add the improved product may prevent that by allowing the system to adapt to the new situation without a code... works sometimes in troublesome situation but it's always good practice. As to WOT, the new part may or may bot add power and may or may not change what the MAF reads.

I'll tell you this. Get a device that allows you to read MAF voltage on the go. Record or datalog the readings in a couple of different situation with the stock setup. Then add your CAI or other intake system mod and do the same. If another truck is anything like my F150 was when I added the CAI, you will see different readings. Maybe not hugely different but different. I don't know enough to comment on the impact small changes will have on EFI operation.

 

[cp3]

I believe JA & Wool are correct, what they are missing is that in this GM application the original MAF housing and associated tube are intact. The OP has not moved the MAF into a new pipe.

Think like the pic here...

Notice the MAF is still in the original tube connected to the air box with the hose clamp for the tube right next to it.

This is not the brand the OP used but a similar idea and I thought a better pic for the purpose.

This should be similar to what was used and as you can see, no MAF port...

 

[05Blazer]

CP3

Exactly my point I was trying to make. On this particular setup, the MAF sensor is built into the factory airbox lid and has remained in its factory position. Just the tubing was changed. I went this route because the factory box already does a max job on pulling in cooler air through the fender well. The restriction is in the tubing baffles from airbox to throttle body.

 

[cp3]

 

[440Magnum]

Originally Posted By: gathermewool
I'm not sure why I'm not conveying my thoughts correctly, but I'll try again:

The MAF sensor will sense what flows past it - do we agree on this?


Well.... that depends on what you mean by "past." I would substitute the word "THROUGH," because the sensor is more than just the anemometer

In the applications I've seen(maybe not all, tho) the MAF sensor is a section of tubing including the sensor inside, and the tubing and sensor are calibrated as a unit. Its not a sort of probe that goes into a separate piece of tubing that gets changed up in a CAI installation. Therefore, you can change all sorts of stuff upstream of the MAF sensor section or downstream of it, but because the sensor includes its own fixed-diameter tubing section, often with airflow straighteners to make sure any turbulance coming into it is cleaned up before flowing over the hot-wire anemometer, it still accurately reads the mass of air flowing through it.

In other words, the designers of the MAF sensor take great care to make it INDEPENDENT of what goes on upstream and downstream. Unless you actually flow some air around ("past") the sensor section, or the resonances are SO extreme that air is bouncing back-and-forth inside the sensor and creating a falsely high mass flow reading, you're not going to cause it to read erroneously.

Speed-density systems, on the other hand, can be fooled several ways. They make assumptions about the mass of air that flows when a) the atmospheric pressure is X and the MAP is M, b) the inlet air temp is Y, c) the throttle position is Z, the RPM is R, and several other things. If you make it so that more air flows for a given RPM/MAP/TP combo, the calculation will be wrong. Also if the atmospheric pressure changes substantially from the initial reading at engine start, there'll be an error. Most of the time, all those errors can be trimmed out by the O2 sensor readings... so its not usually an issue. I'm just saying that this is a system that's more easily fooled than an "all-air-goes-through-the-sensor" MAF system.

But of course, you can screw up anything if you work at it hard enough. That's the corollary to "if you make something idiot-proof, you'll quickly find a better idiot."

 

[Jim Allen]

Originally Posted By: cp3
I believe JA & Wool are correct, what they are missing is that in this GM application the original MAF housing and associated tube are intact. The OP has not moved the MAF into a new pipe.

Think like the pic here...

Notice the MAF is still in the original tube connected to the air box with the hose clamp for the tube right next to it.

This is not the brand the OP used but a similar idea and I thought a better pic for the purpose.

This should be similar to what was used and as you can see, no MAF port...

I didn't miss that this application didn't move the MAF at all. It's entirely possible this tube has no effect on the MAF reading for this GM engine, but generally speaking ANYTHING you change in the airflow this close to the MAF has the potential to change the reading. May not in every case, or in this one. Case by case. I know in my Ford, changing the snorkel tube (leaving the basic air cleaner & MAF mounting intact) will change MAF readings a little.

 

[SteveSRT8]

Potential, that is the key word here.

NP for the OP...

 

[gathermewool]

Sorry for the confusion, guys. I wasn't speaking to the OP's specific case, and stated so in my first post, since his MAF is still installed in the OEM location, in the filter box. I also didn't mean to seem argumentative toward SteveSRT8 (if I even came across that way.) My comment was specific to installing the OEM MAF sensor into an intake tract with a geometric configuration different than OEM, with no tune.

Some aftermarket intakes try very hard to be bolt-onable, like what Jim Allen described, but who is to say how well they've done if you do as they claim you can and simply slap that bad boy on? I'm not saying that every intake will have negative consequences, but it behooves the buyer to do some research and figure things out, like what Jim Allen descibed in AEM's design changes, instead of bolting on something that has the potential to do nothing but lighten your wallet, at best, and cause a decrease in performance or reliability, at worst.

I also agree that if the OEM MAF sensor is installed into an aftermarket intake whose MAF section of piping is similar to OEM, then the scaling shouldn't be affected dramatically. It will still most likely be affected, since changes upstream and downstream of the MAF housing section will create different flow characteristics, changing how the MAF senses a given flow rate from how it was calibrated to sense it with a 100% OEM intake.

More to 440Magnum's point, and partially to SteveSRT8's, the aftermarket intakes available for my STI come with a MAF section that you install the OEM sensor into. Air flows THROUGH this section, but the MAF sensor does not gather ALL OF the air that flows through, so it's really measuring what flows past it, as compared to its reference, which is how it was scaled while installed in the OEM MAF location. If the OEM and aftermarket MAF sensor tubing section is not the same, then what was THROUGH is not what is currently THROUGH, so 'past' seems to be a little more accurate, is all.

 

[440Magnum]

Originally Posted By: gathermewool


More to 440Magnum's point, and partially to SteveSRT8's, the aftermarket intakes available for my STI come with a MAF section that you install the OEM sensor into. Air flows THROUGH this section, but the MAF sensor does not gather ALL OF the air that flows through, so it's really measuring what flows past it, as compared to its reference, which is how it was scaled while installed in the OEM MAF location. If the OEM and aftermarket MAF sensor tubing section is not the same, then what was THROUGH is not what is currently THROUGH, so 'past' seems to be a little more accurate, is all.





That's definitely a different situation, and I would assume one that just about requires re-programming of the fuel map(s) in order to work right. Definitely would skew the MAF sensor reading beyond the point where the O2 sensor can trim things back into the green, so to speak.

 

[SteveSRT8]

Don't worry Matt, no arguments here. Just fun discussion!

And I agree that any changes may be real but in our case (GM V8) there is no difference that will make any real change in the car or hurt the engine, etc.

Typical platform specific stuff.

 

[GMBoy]

Originally Posted By: 05Blazer
From Trusted GM employee at the assembley plan:

You don't need a tune with a cold air intake. The internet forums are wrong. The air still passes thru the MAF sensor and that tells the engine how much air is coming in. The baffles are for noise cancellation purposes.

 

[GMBoy]

Originally Posted By: gathermewool
Originally Posted By: 05Blazer
From Trusted GM employee at the assembley plan:

You don't need a tune with a cold air intake. The internet forums are wrong. The air still passes thru the MAF sensor and that tells the engine how much air is coming in. The baffles are for noise cancellation purposes.


Sorry, but your buddy is 100% wrong on this front. The Mass Airflow sensor is scaled and its values entered into your ECU's memory (it's essentially a lookup table.) If you change the diameter or geometry of your intake, then a larger amount of air could be sucked past the MAF sensor without the MAF sensor actually accounting for it all, since less air would flow past the sensor for the same overall volume.

In this case, the FEEDBACK would be via the ECU reading the discrepancy in the O2 sensor reading from what it what it looked up in that cells respective fueling table and adding or subtracting fuel as necessary. Even if your fuel trims are stored in memory doesn't mean that there won't be times when your ECU can't account for the discrepancy in what tube the MAF sensor was scaled to work with and what you installed. You must either rescale your MAF to work with the new intake or rely upon the ECU to adjust your fuel trim.

Again, the MAF sensor will not account for a change in your intake. The ECU will receive a lean reading from the O2 sensor and adjust your fuel trim after the fact. I'm sure every vehicle is different, but this is how my Subie operates, and this is how I believe all MAF-based fueling systems operate.



Umm..no I am not. You are wrong and try telling that to the Powertrain engineer sitting right behind me. The comment about air getting by the MAF unregistered is very amusing to me. ALL air will go thru it and be registered. A cold air kit does not provide so much more air that the ECM cannot compensate. Now, adding exhaust then you can benefit from a tune. But stock - no way - our system can handle it.

 

[GMBoy]

Originally Posted By: SteveSRT8
Thank God Subaru is not under my hood.

ALL air in the Silverado intake flows THROUGH the MAF.

Unless you have a hole somewhere, you are incorrect.

Wildly platform specific stuff, as the MAF (in this truck) can account for a huge percentage beyond what is actually used in normal operation.


Someone understands!

 

[Smokescreen]

What I don't understand about a lot of air intake (or exhaust) companies is that they never publish:

1) how much CFM your stock engine can ingest (expel).
2) how much restriction the stock intake (exhaust) introduces.
3) how much more air their product can flow.

To me, if they did this it would be cut and dried no brainer.

Instead, "Our product flows more than stock, here is a dyno run we did " under near perfect conditions... "see it makes 8 (or whatever) more hp."

Marketing doesn't tell you that if you are couple of hundred feet more above sea level, its colder with more humidity and the barometric pressure is higher than the one they tested you won't see the same results they did. Even back to back dyno runs can produce 10's of hp variation and they just pick the best results.