Conlusion of the bulletin is to change both filters instead of just one.

Good tip!

 

When I was younger and dumber, I fell for the K&N marketing bulls41t and bought one for my 99 XJR.

After coming across some research and tests, and one day holding up the filter to the light (with only a couple thousand miles) and seeing light coming through many pin ***** holes, I tossed it out.

It had nothing to do with the MAF, but because it wasn't really filtering. Sure it flows more air as well as a hell of a lot more dirt.

Now I have a full custom intake from the throttle body forward that probably messes with the MAF way more than a simple K&N drop in does Sure works great though.

 

Years ago, the air filter on my '99xk8 needed replacing. The tech working on it did say that it would be unwise to replace it with a K & N, specifically citing problems for the MAF. For what it's worth.

Does anyone know who manufactures OEM air filters for older XkR's? Amazon carries
Mann and Beck-Arnley. Are either of these what Jaguar uses? Thanks, guys.

 

My k&n has been on my car for 60,000 miles, no issues that I have observed...MAFS has been cleaned twice in that time period to clear lean conditions and a multiple misfire on one bank when it was really cold on startup.

 

Sheesh! I need to clean the coffee off my screen and drain my keyboard! R U (flippin') kidding me?!? What's a new supercharged XF go for? North of $60k I'd guess? And to avoid codes you have to drive in such a way as to ensure both air filters get evenly loaded with dirt!?!

Steve, you mention "....the one ENGINEERED to ..." and later, "...bulletin, Jaguar Engineering has found ...." and your point is well constructed. However, I charge you, sir, with playing fast and loose with the terminology! The only name for the goat-rope described in the bulletin that has the root "Engineer" in it would be "Engineering Malpractice." If your surgeon performed his/her task with similar aplomb, you (or your heirs, more likely) would be suing him/her for $million$.

Haven't seen the layout, and there may have been severe packaging issues...but offhand I'd say, "hey...guys....why don't we save a few pennies in this design and just use one MAF...we can put it here, in the common tube fed by both filters...."

but they didn't ask me..I'm sure they had their reasons...(even so they mayn't have been "good" ones...) and I didn't respond to argue pro/con of K&N (though to be honest...that bulletin would send me flyin' to the K&N store...at least I could keep two of those matched without buying 2 new ones everytime they mismatch...) I was just amazed at the implications of that bulletin. If I was an XF owner...I'd still be stuck to the overhead over that one. It would be interesting to see how many other such surprises have been launched with that car...

Thanks for posting it. I'm loving my XJ6 all the more....

 

xjrguy, the TSB you posted refers to an imbalance between bank 1 and bank 2 MAFs caused by more air flowing through one filter than the other. The imbalance was caused by replacing one filter and not the other one. In that situation the MAF isn't misreporting the amount of incoming air as you stated above. Each MAF is reporting the correct amount of air. However the ECU can't figure out how much fuel to inject into the cylinders when the two MAFs are reporting different amounts of airflow.

If the "R" had two K&N filters and they were both cleaned at the same time, there would be no imbalance, and the system would work just as it is supposed to. In the normally aspirated cars, the imbalance problem wouldn't be an issue.

 

You missed my point. They are not bank 1 and bank 2 MAF's, they are two MAF's measuring for ONE intake. Therefore if one just saw more air, it shouldn't matter, all the ECM needs is the total. If there is a running issue due to an air filter causing a MAF to mis-report flow, then it must be somehow upsetting the way that MAF sensor reads air flow. Capish?

Cheers,

 

I read the TSB and that's not what is says. It says there is a bank one MAF and a bank two MAF. The problem is caused by an imbalance of airflow between the two sides. It even states the maximum amount of imbalance that is permissible. Each MAF measures the airflow for one intake. If the two MAFs don't report a similar amount of airflow, the ECU can't figure out how much fuel to inject.

That's what the document that you posts states. Capish? Maybe you meant to post a different doc.

 

I'm not convinced of the actual filtering ability of K&N air filters. I had a Chevy pickup on which I had installed a K&N replacement filter, and I kept finding grit in the intake tubing AFTER the filter. I tried various oiling strategies, but no change in the grit problem. I removed the K&N, went back to an ACDELCO paper filter, and no more grit.

I vote no.

 

For the record, I don't have a K&N filter, but the theory behind them is sound. They can have "pinholes" in the filter because it works the same way that humans and other animals filter the air that goes into the lungs. In animals, the sinuses and trachea are covered with mucus. The particulates stick to the mucus. In the K&N filters, the particulates stick to the thin layer of oil. They don't need to have a super-fine mesh because the law of averages states that any particles will most likely collide with the oil covered mesh and stick to it. A dry filter has to have a much finer pore size because it isn't sticky. It can only block particles that are larger than the pore through which the air is flowing.

 

I'll explain it for you, as you are missing what is actually happeneing if you have an uneven flow, for which the TSB advises to have equal filters on both sides.


From cold the ECU is not in closed loop, and it will use (amongst others) the MAF reading as true airflow. Now when 1 filter is dirtier, or one as a completely different filter on one side, you will get a very uneven flow.

It is very difficult to get good true airflow readings at a low flow, and it would not surprise me that in the conditions mentioned in the TSB it could even be halved on 1 side so that WIL cause a reading that is not accurate. The other side obviously flows a little more air, and there once you go higher the accuracy becomes less.

The effect of the slower flow side would be highest, and as the results of both MAF are added together (as they feed both banks thru 1 trhottle opening), you get a wrong reading causing the effects in the TSB.

Capish?

 

 

Dude... that diagram shows exactly what Avos and I are trying to tell you. I don't know why you'd use the icon. The diagram shows two intakes with two air filters and two MAFs.

Here's what the TSB that YOU posted says: "This may be due to variation in the air filter element material causing an imbalance in the intake air flow." and "Air cleaner elements must be replaced as a 'matched' pair."

Apparently the programming in the ECU can't deal with an imbalance between the two MAFs. It has nothing to do with fluid dynamics or turbulence or anything else. It's just the ECU injecting the wrong amount of fuel because it isn't programmed to handle MAF inputs that aren't similar.

 

It's engineering malpractice any way you slice it. That alone tells me the XFR was launched before it was finished. Good luck with 'em....

FWIW, though I'm running K&N's in all the Jags I'm responsible for insuring....they weren't my first choice. I actually prefer the AFE Pro Dry'S I'm running in the trucks. No oil to mess with and thus no MAF fouling, though neither has that been an issue for me with the K&N (there ARE instructions how to oil 'em...after all)

Unfortunately, no joy in finding Pro Dry that would fit the 3.0L S nor the 4.0L x300...

 

Look, we're all friends here, we all want the same thing, to better understand and enjoy our Jaguars. Let's take a breath.
I just haven't yet been able to adequately get my point across. Maybe this illustration will convey more. All of the SC engines have the same intake setup, no matter whether there are two air boxes or one. All the air comes together and does not split to bank one or bank two until it enters the charge air coolers. I contend that as long as the incoming air is measured correctly, it should not matter if one side saw a little more than the other, it all goes the same place, the total air is what the ECM needs. I feel that for an imbalance to cause problems, it must be upsetting the air measurement by one MAF sensor.

With that, everyone, whatever filter you use, please enjoy your Jaguars to the fullest! There ain't nothin' like 'em!!

Cheers,

 

Obviously you don’t take my word for it, and by keeping your own view without having the knowledge on how MAFs work but yet disregard other possibilities as if you do, sounds like you are indeed prejudice about this subject . It is probably my poor English writing skills; please forgive me as English is not my main language.

To give you an example on one of my test MAFs: The error margin (professionally measured by MAF specialists) for idle (about 6 gr/sec, or 20 kg/hour) showed an error margin of about 18.73%. Now if I would half this (to mimic the effects of one side having a dirty filter and the other clean), the error margin grows to 24.41%. Don’t look at the actual error margin percentage, but the difference, as that is what plays an important role. Then an imbalance of 2.5 kg/hour could be quickly reached as stated in the TSB.

Now combine the 2 thoughts, and you will see there is no easy black and white answer, it all has an effect to different degrees.

So for the dual air intake systems, the K&N could actually help in reducing the imbalance over time, as it takes longer for these units to become affected by dirt. On the other hand it also means you need to clean/and oil them both equally, but that is doable if you follow the instructions. Please note this is just an assumption…

I have no affiliation with K&N, and if I would experience negative sides of these I would mention that, one of them being that you need to oil them right.

 

That is incorrect. If there are two air boxes one box is considered bank one and the other is considered bank 2. Look at this from the TSB you posted:



Jaguar considers one air box as bank one and the other bank two. Each bank has its own MAF sensor.

I completely agree with you there. I would guess that Jag techs and the engineers who designed the system would agree with you, too. However the ECU isn't capable of adding up the air flow from the two MAFs. It gets confused when the two sensors don't match. That's why the TSB says that the air filters should be replaced as a pair. As long as the filters are replaced as a pair, the ECU won't get confused.


I disagree. Both MAF sensors are reporting the correct flow, but if there is a difference in the airflow between one bank (airbox) and the other, then the ECU doesn't know how much fuel to inject. That causes the engine to run rough.

I understand what you're saying, and I even understand the physics behind it, but I don't think that's what the TSB is saying. I work in the fire alarm industry and most air handling units have smoke detectors in the ductwork. The smoke detectors have to be installed in areas where there is no turbulence in the airflow through the ductwork. In other words, they can't be near any bends, tees, vents, dampers, or anything else that causes the air to tumble within the duct. If the air is turbulent, the smoke detector won't work properly. For the duct smoke detector to operate properly, it has to be a minimum of 6 duct widths downstream of any bends, obstructions, etc. That allows the air to assume a more laminar flow before entering the smoke detector. You're saying that the MAF sensor is similar to the smoke detector and it requires [somewhat] laminar airflow to work properly. That may be the case, and if it is, I'm sure the engineers designed the system so that the MAF sensor was located somewhere where it could accurately measure the airflow. If the air filter was going to affect the accuracy of the MAF sensor, then they would have located the air filter somewhere else. If anything, the K&N filter would be less disruptive to the airflow than a paper filter. It doesn't have all of the folds that cause different amounts of airflow from different points on the filter. The air can flow smoothly through the K&N whereas it cannot do that through a paper filter.

We agree again!

 

You guys are all sweating over just one angle - the MAF. Keep in mind that there are other sensors like the IAT (Intake temperature sensor) and this one can give different readings if the flow of air is higher than expected (something K&N filters will give - more airflow).

All those readings are happening live in real time as the engine runs. Then there is the gas pedal (human input), the gear selected, normal or sport mode, etc etc...

All these inputs combined feed the software that is burnt into the ECU and this software makes decisions based on all these things, on the fly.

I don't care if K&N sponsors this site, don't tell me that their engineers understand all ECU softwares of all car models they sell air filters to. They don't.

So I stick with the ORIGINAL engineer-chosen filter for the car I drive. Having said that, if I'd go with lots of other modifications, than all bets are off and I would need a very good NERD to tinker with the ECU software. Not going to happen. The ECU software is one of the most guarded secrets of each manufacturer, and the people that actually know all the ins and outs of it are already working at their respective car manufacturers.

So if anyone wants to use K&N just go ahead and use it. I'm just saying that I wouldn't. Been there, done that, got the t-shirt.

 

This is not correct. Yes air temp & barometric pressure all play a role, but not with the issue adrressed in the TSB, that only deals with an imbalance. It doesn't matter if you run 6gr of air/sec at 20C or 12 gr/s at 20C, it stays 20C.

Most likeley, but they also don't need too imho. All they need to understand is airflow, filterbox/intake design and MAF sensors. Have of course no idea if they have tested the specific jaguar ones, one could ask them.


Can't see the relation, but I agree, once you are able to get more air into the engine you also need a filter that is able to do that. There is no need for altering the ECU software though in this case, there is plenty of room when it comes to extra airflow.

 

I think you guys read and think too much, if you want to spend 60 bux , u can paypal me that money otherwise stay with your current air filter until it goes bad, is K&N filter better than your stock filter? Yes of course, will it magically boost your engine's power? No. Will your engine breathe better? Yes. Will you get better gas mileage? No. Do you need a mapping bs? No, and Idk how people can make up things like this, Can you swap your filter with a bathroom sponge? Yes. If you get the K&N filter will your MAF go bad? It may, because of the oil, you never know. If the MAF goes bad will Jaguar replace it for me? Depends on your service, mine wouldn't. So after all you still want to get K&N go for it, I'd go with a cold air intake, but thats because I'm nuts, and I know all the people on here will go like ; Oh my the cold air intake ruins your engine, it actually lets warm air gets in to engine , Will they change my mind about cold air intakes? No. Do I have a cold air intake on my jag? Yes. Does it improve the engine performance, Yes. How do you know it does? I get better 0-60 times, and the engine roars better.