Here we go again rbartick! Do you look for my posts so you can make me look bad? (Pretty easy to do sometimes)

I guess I have to choose my words carefully around you. I don't give answers as technically worded as you do...one reason being that you know much more about the subject than I do.

I do stand by what I said, but let me explain what I meant. It is the increased volume of air that the aftermarket intakes provide that causes the turbulence in the MAF. The turbulence doesn't happen under stock conditions, but once more air is forced through the system via the larger intake, etc., turbulence is the result. The turbulence wouldn't be present if it weren't for the increase in air volume.

In the future I will try to be more verbose, explicit, exceedingly complicated and generally more cerebrally based.

 

It is not my intention to upset you.

If you monitor the readings from the various sensors you will see that during closed loop your aftermarket box is not flowing more air than the stock box. Do you really think that your aftermarket box is flowing more air than the stock unit when cruising down the road closed loop at 1/4 throttle and low RPM? This is when the code is being thrown and the stock box is not an airflow limitation under these conditions.

 

You did not upset me...didn't you see the smiley face? I put that there just so you would know that I was being facetious. The first couple of lines were tongue in cheek. The rest was my attempt to explain what I was trying to say in the previous post.

I still assert that it is the aftermarket intake that is causing the code due to the increase in air flowing through the aftermarket intake. Do you really think that a larger filter, air bridge, and coupler aren't going to increase the volume of air coming into the car at any rpm? Of course it does. If the car had a 5 inch hole in the front end it would flow a certain volume of air at 25 mph. If I cut a larger hole...say 8 inches, there will be more air flowing through the hole at 25 mph then there was through the 5 inch hole...this is just common sense. There is a certain amount of air flowing through the stock box at closed loop, 1/4 throttle and low rpm, to use your circumstances. Under those same circumstances but with a larger more freely flowing intake, there will clearly be more air flowing into the engine. It is the increased air volume that creates the turbulence through the MAF. What else would cause it if the two intakes, as you assert, flow the same amount of air under the same given conditions. Something is causing the turbulence.

Using your reasoning, the new intake makes no difference at all because it isn't flowing more air than the stock box at low speed and rpm, and yet the MAF senses turbulence. What is causing that turbulence if it isn't the increased air flow for which the MAF is not programmed under closed loop?

So...to answer your question:Yes I do! It is larger than the stock unit and therefore is obviously going to flow more air under all conditions.

That's all folks!

 

When cruising at light throttle and low-rpm the throttle body is the airflow restriction. The aftermarket airbox only provides additional airflow into the motor when the CFM into the throttle body exceeds the CFM limit of the stock airbox. The stock airbox is able to satisfy the CFM requirements of part throttle low rpm cruising.

If you want to dispute this statement try the following test. Find a very flat section of road and set your cruise control to 55 MPH in 6th gear. Use an ODBC scan tool to monitor the TPS with the stock airbox. Swap the airbox and immediately repeat the test on the same day, same exact section of road with the same exact weather conditions. All conditions have to be the same (except the airbox). If your aftermarket airbox is flowing more air into the motor at a 55 MPH cruise then you should see a smaller TPS than you did with the stock airbox.

 

When cruising at light throttle and low-rpm the throttle body is the airflow restriction. The aftermarket airbox only provides additional airflow into the motor when the CFM into the throttle body exceeds the CFM limit of the stock airbox. The stock airbox is able to satisfy the CFM requirements of part throttle low rpm cruising.

If you want to dispute this statement try the following test. Find a very flat section of road and set your cruise control to 55 MPH in 6th gear. Use an ODBC scan tool to monitor the TPS with the stock airbox. Swap the airbox and immediately repeat the test on the same day, same exact section of road with the same exact weather conditions. All conditions have to be the same (except the airbox). If your aftermarket airbox is flowing more air into the motor at a 55 MPH cruise then you should see a smaller TPS than you did with the stock airbox.

Put a straw in your mouth and try to breath slowly through it while sitting at your desk. No problem doing that. Try to breath through that same straw while running or jogging. Now we have a problem.

 

I understand what you are saying...these comments don't answer the primary question. What causes the turbulence in the MAF? It has to be air, it sure isn't water! Again...think about this from a simple common sense approach. Your conjecture is that there is the same amount of air entering the MAF under closed loop conditions no matter what intake is one the car. If this is true then why would an aftermarket intake cause the MAF to throw a code if the two intakes allow exactly the same amount of air in closed loop operation. The aftermarket intake is obviously creating conditions that are different than the stock airbox. Using your thesis the aftermarket intake changes nothing until it is in open loop mode, and yet the MAF codes come under closed loop opertation when, supposedly, the aftermarket intake provides no more air then the stock box. It is substantially larger than the stock box and therefore is logically going to provide an increased amount of air under all conditions. This doesn't mean that the engine is going to use it all, but it is there nonetheless.

To put it simply, if an increased amount of air is available, with no place to go, then turbulence will be the result. If not, then what in your opinion is causing the turbulence?

 

Quote:

Originally Posted by Scott04Z

To put it simply, if an increased amount of air is available, with no place to go, then turbulence will be the result. If not, then what in your opinion is causing the turbulence?

The engine is an air pump and it pulls air like a vacuum. The airbox does not just allow extra air to enter with nowhere to go. The engine always commands the air (unless you run forced induction).

Quote:

Your conjecture is that there is the same amount of air entering the MAF under closed loop conditions no matter what intake is one the car.

I said that is true as long as the stock airbox’s CFM rating is well above the CFM that the stock motor will pull when cruising close loop. Lets assume that when running down the highway at 55 MPH in 6th gear your engine is putting out 50 HP. Lets also assume that 50 HP at 1200 RPM equals about 40 CFM into the throttle body and high engine vacuum. This 40 CFM is determined by the design of your motor and it is unrelated to your airbox. If the stock airbox is capable of flowing 600 CFM then it will not be a restriction when the motor is pulling 40 CFM through the throttle body. You could run with no airbox at all and 50 HP at 1200 RPM would still be 40 CFM through the throttle body.

Another way to check your airbox without an OBDC scan tool would be a vacuum gauge. Hook a gauge to the intake manifold and monitor engine vacuum with the stock box when cruising 55 MPH in top gear on a flat road. Swap the box and repeat the test on the same road, same speed, same weather conditions with an aftermarket box. If your new box is now flowing more air engine vacuum should increase. The reason engine vacuum would increase is the “additional air” would be mixed with additional fuel by the PCM to maintain stoich. This would result in more power and your road speed would increase with the same throttle opening you used with the stock box. To slow back down to 55 you would have to close the throttle a bit, TPS would go down and engine vacuum would go up.

The only time the aftermarket airbox is going to flow more than the stock box is when the CFM into the throttle body exceeds the CFM rating of the stock box. That should only be happening when there is a zero pressure drop across the throttle body (WOT, zero engine vacuum). As far as what is causing turbulence, we would need to consult a fluid mechanics textbook to answer that. I am guessing that the bends (or lack of) in the intake tubing are responsible. Any changes to the shape and length of the tubing will change the airflow characteristics in the tube.

 

Quote:

Originally Posted by Scott04Z

To put it simply, if an increased amount of air is available, with no place to go, then turbulence will be the result. If not, then what in your opinion is causing the turbulence?

The engine is an air pump and it pulls air like a vacuum. The airbox does not just allow extra air to enter with nowhere to go. The engine always commands the air (unless you run forced induction).

Quote:

Your conjecture is that there is the same amount of air entering the MAF under closed loop conditions no matter what intake is one the car.

I said that is true as long as the stock airbox’s CFM rating is well above the CFM that the stock motor will pull when cruising close loop. Lets assume that when running down the highway at 55 MPH in 6th gear your engine is putting out 50 HP. Lets also assume that 50 HP at 1200 RPM equals about 40 CFM into the throttle body and high engine vacuum. This 40 CFM is determined by the design of your motor and it is unrelated to your airbox. If the stock airbox is capable of flowing 600 CFM then it will not be a restriction when the motor is pulling 40 CFM through the throttle body. You could run with no airbox at all and 50 HP at 1200 RPM would still be 40 CFM through the throttle body.

Another way to check your airbox without an OBDC scan tool would be a vacuum gauge. Hook a gauge to the intake manifold and monitor engine vacuum with the stock box when cruising 55 MPH in top gear on a flat road. Swap the box and repeat the test on the same road, same speed, same weather conditions with an aftermarket box. If your new box is now flowing more air engine vacuum should increase. The reason engine vacuum would increase is the “additional air” would be mixed with additional fuel by the PCM to maintain stoich. This would result in more power and your road speed would increase with the same throttle opening you used with the stock box. To slow back down to 55 you would have to close the throttle a bit, TPS would go down and engine vacuum would go up.

The only time the aftermarket airbox is going to flow more than the stock box is when the CFM into the throttle body exceeds the CFM rating of the stock box. That should only be happening when there is a zero pressure drop across the throttle body (WOT, zero engine vacuum). As far as what is causing turbulence, we would need to consult a fluid mechanics textbook to answer that. I am guessing that the bends (or lack of) in the intake tubing are responsible. Any changes to the shape and length of the tubing will change the airflow characteristics in the tube. The screen used on most MAFs was designed to combat turbulence across the MAF.

 

Your command of these facts is impressive, and I have already said that I have far less understanding of the computer side of things than you do. However, I didn't claim complete stupidity. I understand that the engine is an air pump and that vacuum is a factor in our discussion.

I don't disagree with most of what you've said....I even think I understand a good bit of it! If you look back at the original post which you responded to, I said that the increased amount of air that an aftermarket airbox provides is a factor in the codes that the PCM throws. That is an accurate statement, just not fully fleshed out as you have done. I think you are making a bit much of what I haven't said and basing some of your points on the assumption that I am not considering these issues.

What I can't buy in your argument is the cause of turbulence and that is the basic crux of my point.

It has to be more than just the shape of the intake that causes the problem...it is it's capacity to flow air that results in turbulence under the right conditions. If it were the shape only than one could alter the stock airbox in some way that redirected the air and thus throw a code. But this doesn't happen in real world situations. There are guys with extra holes in the stock box or running with the zip tie mod and they have no code issues that I have heard of. But when an aftermarket is involved then codes become common. Why? It is their ability to flow more air than the stock box. This air is available at various quantities, based on demand, but even at idle the aftermarket intake makes more air available than the stock intake does. The MAF is pre-T/B and thus can be affected by the increased air whether or not the engine is asking for it. This can cause turbulent air in the MAF.

Turbulence is defined by Webster's dictionary as "disturbed; in commotion, varying irregularly, tumultuous, riotous".

This definition basically confirms what I have been saying. Air movement is what causes turbulence, and in the case of our discussion, it is air in the aftermarket intake which is responsible for this.

Perhaps we will have to agree to disagree on this point...it is the only point in the discussion upon which we apparently disagree. In any case, we aren't helping the person who originally posted with his problem anymore and so it is a mute issue at this point.