MDX Performance & MPG for Less? I think so!!

No offense intended, but you are living in a dream world if you actually believe all this. Just to focus on one point for example, on a modern engine an air filter will have absolutely no effect on gas mileage. None, zippo, zilch. This is because the computer constantly reads the A/F ratio via the oxygen sensor and adjusts it accordingly to keep it at the preprogrammed point. You could run with no air filter and this would not change the A/F ratio and thus would also not change the fuel mileage. A K&N might or might not buy you a very small horsepower gain but it will do nothing for mileage. Synthetic oil (I run it in all my cars - Mobile 1) will buy you a very small mileage and horsepower increase but it is nowhere as dramatic as the numbers you suggest.

Some interesting tests were done a few years back using a double blind system. People were given cars to drive and their mileage and performance evaluations were logged. The cars were then taken away from then and given back and they were told that a variety of performance and milesage modifications had been done. Again, they were told to drive them and their mileage and observations were logged. The drivers reported that they felt improved performance and there fuel mileage numbers did indeed go up a little. The interesting point: In fact, nothing at all had been done to half the cars and yet those drivers reported similiar improvements and recorded similiar mileage gains to the drivers of cars that had been modified. The conclusion was that the improvement was brought about by mental suggestion (in the case of performance) and the driver's adapting slightly different driving methods based on what they expected the outcome to be (in the case of fuel mileage). Interestingly, the stronger the pretest belief that such things worked by the individual tester, the stronger the noted "improvement."

chris.soto said:

Note:
I
Gas mileage increase of 4+MPG
See the above links for testimonials. I expect at least 2 MPG from the filter and oil.

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mikedan,

The brand is Maniik. All black unlike the previously posted flyer pics.

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RedMdxMemphis,

I mean the "I think so!!" to be dramatic and kind of humerouse. I guess it didn't work. I have (but didn't mention) used synthetic oi for years with what I felt to be a benefit in hp and mileage.

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mogur,

Thanks for the "no offense" comment. None taken.
I appreciate what seems like a very educated opinion.
If I can get the car to a Dyno test I will.

I have it from an excellent source, that if you put racing stripes on you'll get AT LEAST 15 HP and 25 ftlbs of torque.

If you add ground effects spoilers, yopu will get another 50HP.

I also heard that changing out the stereo will pick up 10 hp.

A big coffee can lashed onto the exhaust tip will get a MINIMUM of 15HP.

Heck, if you install all the bolt on products bouncing around, the MDX should be pushing 520 HP EASY.

Any bolt on exhaust/intake air filter mod will get you nothing (or close to it) If anything, it would effect WOT readings (wide open throttle) at higher RPMs where airflow is a factor. (Read near redline..)

Real changes: change ECU programming, intall bigger injectors, change valve timing. - Now we talkin'.

mogur nailed it in his post.

Ard

Re: Re: Re: MDX Performance & MPG for Less? I think so!!

The oxygen sensor measures the a/f ratio by varying a voltage tightly around the ideal a/f rato of 14.7 to 1. (This is called the styrichometric ratio.) The computer reads this voltage to maintain the A/f ratio at 14.7 to 1. The only exception is at WOT when it is allowed to go open-circuit and exceed the richness dictated by the sensor. No matter what you do in the intake circuit the oxygen sensor and ECU will maintain the same ratio. Thus, it has no effect on gas mileage as there is a direct and unalterable ratio between A/F ratio on the intake side and the oxygen level on the exhaust side. A dirty air filter actually lowers gas mileage on a modern car differently than it did on older cars. On an older car, it actually did change the A/F ratio since there was no feedback in the system. On a newer car, within reason of course, it will have no effect since the ECU will compensate. If the filter does get dirty enough, however, and that would have to be VERY dirty, it will increase the intake tract vacuum and that will in turn increase pumping losses and lead to a slight loss in gas mileage. This is an extreme example though and a dirty filter will effect performance be limiting the air which may be drwan in long before it will effect gas mileage. If you want more information on this, the MDX Service Manual has some excellent technical details and specifics.

Tom

golfski said:

This is not technically correct. The oxygen sensor measures oxygen levels in the EXHAUST gases, and the ECU will take this reading and makes adjustments to the A/F ratio to achieve the proper exhaust gas oxygen reading. The A/F ratio is a variable that's changed dynamically by the ECU - it's not set at a pre-programmed point - it's constantly changing due to a variety of factors. An airfilter can, in fact, have a significant effect on gas mileage. To imagine this, reverse your example (instead of no airfilter, imagine a highly restrictive or clogged airfilter). Not only would performance suffer, but mileage too.

I posted my doubts about significant MDX HP gains, from a K&N filter alone, in another thread. However, there are applications where a K&N filter alone WILL help to make noticeable power gains - I just don't think the MDX is one of them....

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Ardvarkus Mods

After trying to picture the MDX with all the mods that Ardvarkus described above I got to wondering just what this vehicle would look like...
My deepest apologies to GTO-Dave for using has picture from the gallery as a starting point...
Can you tell today is a snow day here... things sure are slow... Yes, I did go drive the MDX in the snow... it totally rocked!

So, here it is... Pictured with the optional "Clapper" remote entry.

Why a K&N filter increased mileage

This is my take on K&N. A K&N filter - assuming it offers less air resistance than stock - will improve power or gas mileage the same way a pair of headers would . . . BUT not at WOT.

Imagine sucking a milkshake through a small and large straw. The large straw offers less resistance and is easier for you to suck the same fluid through - your body's diaphram does not need to exert as much force as through the smaller straw.

Inside your engine, on the piston's downstroke -the piston creates a vaccum filled by air coming in from the filter, the vacuum directly opposes the downward force of the piston. Now if there is less restriction the air will flow quicker, consequently the negative vaccuum force (trying to pull the piston back up) decreases w/ a less restrictive filter. The engine does not need to work as hard to maintain or achieve the same RPM. Voila, you have increased gas mileage. This principal applies exactly to exhaust headers in that there is less force required to push the piston back up on the "exhaust stroke."

Once you have established better flow you can either drive and accelerate at the same rate and save GAS . . .or you can drive and accelerate harder than stock "waste" gas and save TIME.

That being said, a drop in replacement filter probably won't increaes air flow that much. One may feel the extra power from a conical filter w/o the airbox.

rkrans

Re: Re: Re: Re: MDX Performance & MPG for Less? I think so!!

mogur said:

The oxygen sensor measures the a/f ratio by varying a voltage tightly around the ideal a/f rato of 14.7 to 1. (This is called the styrichometric ratio.) The computer reads this voltage to maintain the A/f ratio at 14.7 to 1. The only exception is at WOT when it is allowed to go open-circuit and exceed the richness dictated by the sensor. No matter what you do in the intake circuit the oxygen sensor and ECU will maintain the same ratio. Thus, it has no effect on gas mileage as there is a direct and unalterable ratio between A/F ratio on the intake side and the oxygen level on the exhaust side.

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Tom

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I think the confusion arises because of the terminology. The A/F is, after all, a ratio. Therefore, even if this ratio is kept constant, the variation on the A and the F (in absolute terms) has a direct gas mileage effect. The principal of a freer intake system (eg - a K&N filter), is to allow the A of the A/F ratio to be higher for a given throttle position, with the following expected result: More A which means more F, which generally means more power (for a given throttle position). That's the principal, at least. For the MDX, I'm of the opinion that the intake is fairly well tuned out of the box, therefore, a simple mod like replacing the air filter will have minimal effects.

WRT to the oxygen sensor, remember that it's only reading oxygen levels in the exhaust gases and producing a voltage output that is interpreted by the ECU. In ideal, or design, conditions, this might mean that the A/F ratio maintains a certain target. However, if conditions aren't ideal, then the result will be poor performance and mileage as the ECU hunts around to try to regain the target oxygen sensor voltage output. The other thing to keep in mind is the variables that the ECU can control. It can't control the A side of the A/F ratio to the same extent that it can control the F side (for the simple reason that the A side is effected by altitude, air quality, cleanliness of the air filter, etc).