MAF Sensor and Intake Diameter Modifications? (76mm Throttle Body)

I'm picking up a 76mm throttle body and adapter in a bit from another local member.

If I use universal intake piping parts to make a larger diameter intake pipe from the TRD airbox to the 76mm throttle body, will this totally screw up the MAF sensor readings?

In other words...is the MAF sensor reading based on intake diameter as a constant?

I'll definitely wait until I have AFR monitor running in the truck before installing anything.

Thanks!

 

Yea the MAF calculations are related to the form of inlet tube. Just begin your transition to 76 mm after the MAF position. This part of the tube is not the bottle neck of your setup. The bottle neck will still be at the flange on the SC side. After botling your plate adapter take a look inside and you'll see.

I've installed a 70mm TB with adapter and after installing the plate we put a vacuum in the SC inlet and have port the inlet and the plate.

 

subbed for outcome.......................


what is the desired outcome actually?

 

Lol no specific goal in mind other than to satisfy my curiosity and maybe gain a few horses

Once URD ships my Y-pipe and I get the AFR monitor running I'll feel comfortable playing with this Got the throttle body and URD 76mm adapter for half a benji.

 

MAF Cali....

 

MAF sensors are set to calculate airflow based on air passing through the sensor, and have no changes to the signal by a larger throttle body, or larger air intake. The sensor is calibrated to it's OWN opening diameter, not the throttle body.

 

I have to disagree about its own opening. For this reason, it is why some aftermarket intake manufacturers have a reduced size (stock size) section in their larger diameter intake tubes. Right where the MAF sensor is. Due to the fact that the programming of the ecu is for whatever that specific diameter is, of the OEM.

On the X-1, there is a parameter for the MAF sensor, to be able to change diameter variable incase there is something custom. Volant intakes had a slightly larger intake diameter, if I remember correctly.

Using that diameter size, plus the speed at which the air flow between the two sensors, is how you get you measurement of grams per second (MAF g/s) flow. I.E. Volume.

So to reiterate what Vassily stated, just get a reducer coupling to attach the 3" tube to the larger throttle body. I purchased a 3"-3.5" coupling. It was just a little too big. I still need to get the 3"-3.25" coupling. It will fit much better.

 

^ This is what my thoughts were.

Because of the constriction where the throttle body bolts up to the supercharger, I wonder if the MAF will read less flow with a larger diameter intake.

 

I would like to see some documentation showing this. I have worked with MAF sensors and modifications ever since MAF sensors were introduced years ago. All the documentation and training information, as well as physics and logic, show that the MAF sensor will read correct airflow no matter the side of the inlet, or outlet, for the MAF sensor.

If airflow increases because a throttle body opening is larger, the MAF sensor is quite capable of detecting this. Think basic airflow management and logic. The MAF sensor can read the correct airflow if your throttle plates are say 50% open, which would be the same airflow of a WOT of a throttle body with 1/2 the diameter. So why would it not be quite capable of reading the correct airflow if you install a different throttle body?

I am open to new information, so please, if you have information supporting what you are saying, please link it because I would like to read it if it shows MAF technology has changed recently.

 

From my own experience, that's true. I replaced the stock plastic intake manifold and 46mm throttle body on my Yaris with a larger aluminum intake manifold and a larger 55mm throttle body from a Corolla...



... and as long as the MAF sensor remained within it's stock tubing diameter section, it worked just fine with no codes thrown. The air filter and intake in front of the MAF sensor is also larger.

Greg

 

You're right cause the tubing at the location of the MAF is the same. BAMA saying a different thing. He says no mater the diameter at the MAF location.

SmanZ were looking if changing the diameter of the tube at the MAF location will change something. And the answer as you stated is yes. Maybe the ECM will be able to correct the results with the TRIM and maintain the AFR at CL, maybe not.

The MAF is not calculating the aiflow, it's the ECM that doing this job. The MAF is mesuring the air density via the temp of the air and the air velocity. At a given and same air velocity the total airflow will be more important in a 3in. pipe then a 2 in. pipe. So the calculation of the airflow is related to the cross section of the tube at the MAF location. It's true at least for the model of MAF we have on our truck (inserted).

But like i always said, i can be wrong.

 

The way I read the question raised related to the intake tubing size around the MAF snesor, not the TB itself, but maybe I missed something. One of the benefits of the MAF sensor is that it can adjust for internal mods, to a certain point, but the ECU itself is "hard-wired" to the intake pipe cross section at the MAF install point.

 

Incorrect. That is NOT what I was saying. What I was saying is that the MAF sensor is calibrated based on it's OWN opening diameter. So if the MAF sensor is built with an opening of 50mm, then it is calibrated as such. Double check what I posted.

The MAF signal is based solely on one thing, and one thing only, and that is how much current is required to maintain the temperature of the two thin platinum wires in the airstream. The ECU then uses this information, as well as the intake air temperature signal (Which in the case of the Tacoma is in the same sensor) to calculate the actual volume of air.

 

Sorry BAM,

My mistake .

 

Nope. You sir are correct, and upon thinking about it, and asking about it from another respected source, you are correct again and it just makes more sense to be that way. Less chance for errors. Plain and simple.

Years ago, when I first got into modding, and was dealing with the X-1, there was a lot of discussion about the MAF being calibrated to diameter of the tubing. I believe it was from two quite respected sources. As well as others "in the know". Either way, I just went along with it because it made sense. The question is though, why does the X-1 have a parameter for the I.D. to be changeable?

 

I've seen two different kinds of MAF sensors. One where the wire runs across the diameter of the housing, like this one;



But the one in the 1GR is a little different;


So what I'm thinking is the first type is tied to the diameter of the housing and I wouldn't expect much change if you put larger piping in front of it.

But the MAF on the 1GR could be mounted to whatever size intake pipe you wanted. I was concerned in doing so that it wouldn't take the change in pipe diameter into consideration.

Ok...so in the setup posted by tooter, the MAF reading shouldn't change since the MAF housing is the same.

What do you all think happens when the intake diameter is reduced to stock size after the MAF sensor, as in the OEM intake manifold or TRD S/C manifold with a URD throttle body adapter?

I'm thinking that if the intake manifold is the choke point and you place the MAF in a larger housing, it will read reduced air flow over stock. My thoughts being that a larger housing will result in less air flow velocity past the MAF for a given flow rate...maybe causing lean conditions?

 

I should have paid more attention to the other points, when I first looked in this thread. Being that your truck has a s/c, then the inlet of the s/c will be the restriction. More so than if you have the N/A intake, and adapter. Even though just by a tiny bit.

Back to what I was saying about the MAF sensor and tubing diameter. I wasn't completely wrong, I was just under informed. Yes the MAF sensor still works in the method described by BAMA. Where my understanding started, basically, was that if another value was added by an aftermarket ECU, it could take into effect tubing diameter changes, so that it would have a more accurate understanding of the amount of air coming in. Thus being able to tune out any discrepancies. Which is why (Tacomas in this case) URD has different calibration files for different intakes. Whether that be on the MAF-Cal, X-1, or UCON. To keep the AFR's safe and accurate. The OEM ECM, just isn't designed to encompass all of those variances.

This is why tubing size changes around the MAF sensor, when not using an aftermarket ECU, have to be considered carefully, or your AFR's can range from extremely rich or extremely lean.

Case in point: http://www.injen.com/content.asp?code=mrtech. Good description there. There are also correlating articles on this in DSPORT or Import Tuner. I would have to do some more digging.

Which TRD intake do you have?

 

That's what I understood you to say, Bama.

The diameter of the inlet and outlet are irrelevant. Only the diameter tubing where the air passes by the MAF matters. And it doesn't take much. The MAF tubing section is only 4 inches long. The intake tubing and throttle body diameter on each side of the MAF tube are both larger.

Greg

 

So if you don't increase your MAF diameter and correct airflow input #'s why or how will larger tubes or throttle bodies increase any airflow?