Hi folks.
How far away does the MAF sensor have to be from the throttle body?
I'm thinking of just running it directly though the bonnet or hood to an air filter in order to bypass the plastic piping and get direct cold air intake.
I could also just extend the wiring harness lead to make it fit so...
I'm only theorizing so before you tell me it would make the car look ugly don't.

cheers

 

just a question, isn’t the air already cool as possible by sourcing it from the wheel cavity ?


Z

 

Not really hence folks changing out the plastic piping for the alternative Mina aluminum one which is still subject to engine heat. My thinking is that if there is no pipe to get from the airbox in the engine bay to the throttle body then the air will be by default cooler than even an aluminum piping or even a silicon piping.
The link below is for the Mina air pipe available on E-bay to give you an idea, too expensive in my opinion for what it is.
Mina Air Intake

 

Short answer is that the distance doesn't really matter. What is important is that the airflow through the MAF is smooth and not turbulent so you will want to avoid any hard bends immediately before or after the MAF.

 

Yes that is very pretty, although I don't get why you would want the air filter drawing air from the engine bay.

What is your thought train - an opening in the bonnet and an air scoop or something similar?

 

Open the hood and touch any plastic part. Then touch any aluminum part ( not the thermostat housing ). The plastic will always be cooler. A plastic tube picks up way less heat than aluminum.

any benefit the Mina part has is from the smoothing of the airflow, not any cooling .

Z

 

Exactly, an air scoop or something just running verticle from the throttle body.

 

Ok, point taken. To my mind though less piping equals greater air flow, no bends to slow it down.

 

The reason I bought the Mina intake pipe had nothing to do with performance. Instead, I did it because the aluminum pipe would not disintegrate after a few years like the plastic one did.

 

The same part is on Minas website for $185.00. I've been thinking of replacing my plastic one for the same reason Giandaniel stated.
https://www.minagallery.com/jaguar-x...take-tube-pkg/

 

I’ve got a spare plastic one in good condition if anyone is needing / wanting one.

Still using my original intake pipe, as it’s still in as-new condition some 21 years - 171,000 miles later.


Z

 

I'm not looking to debate the pros and cons of the Mina intake so please no further input about it. The topic of this thread is distance of MAF to throttle body thank you.

 

since it sounds like you are going to ditch the OEM intake pipe you could use it to experiment with the MAF-to-TB distance efficiency by progressively cutting off a 25mm section of it at a time. Then testing the results.

it should be easily observed if you are making positive progress, or not.

Z

 

Thanks for your reply. It's more of an idea at this stage and hoping that somebody would know the distannce. Sound advice though, cheers.

 

I am not sure AFM really measure air flow. I think it is better to think of them as sensors that measure something related to air flow, and only for air going through it (not the entire intake section). And that has to be a function of the air box design, particulars of the air filter, sensor position, etc. From an engineering stand point, if you have a curve like that from a cheap sensor, all you have to do is measure the actual air flow separately in the lab with the same intake and then map the 2 curves. The counter point to this argument is that all late XK8s seem to have the same AFM part# as a bunch of other cars (maybe they have a very similar air intake design, with the flat filter and the tube at an angle, maybe it is some sort of well researched design with optimum emissions compliance).OTOH, early XK8s and XKRs have their own part#.

The answer to your question is probably recursive. The proper position for the AFM in a new intake design is the one that gives you the same readings as the stock setup. It is probably doable on your own. Start with the stock setup and repair everything so your fuel trims are as close to zero as you can get them. Then swap intake and check again, but remember that fuel trims are the elevation of a sort of 3-D map with Load and Rpm as flat coordinates (Torque Pro can draw that) so you will have to visit as many locations as possible. If these trims get too high (say 5% more that the baseline), then maybe consider moving the AFM and see how the numbers change.

I suppose the alternative is to procure a programmable AFM that you can "map" on your own. Or even "capture" the reading of the stock AFM, and then "re-map" it with some form of computer before feeding it back to the ECU.

Best of luck, keep us posted.

 

Plus it would make the car look ugly. 😂

 

Thank you once again for your very comprehensive help and advice fmertz, much appreciated.