stage 2+ cone filters and maf

[Just Sean]

So I noticed a trend that people with cone filters/unenclosed filters are eating through mafs, which unplugged either puts the car into limp or chucks loads of fuel in.

Is their a way we can fix this and get rif of the maf or do some testing to see what the problem is? Can it be mapped out and thrown away altogether?

Ive jad to undo my maf and it took almost 150 miles of a tank!

This is aimed at poodle/mrwhippy and anyone running a cone or unenclosed!

[GTI 6]

Standard air box with k&n panel filter in it or a Bmc inclosed induction kit open filters are a waste of Time IMO

[Eeyore]

K&N Panel filter would be just as good I would have thought. Johnny will be able to put some light on this subject.

[Just Sean]

I was thinking an open filtering for mine as I'm after more airflow. But if I'm buying mafs like consumables then I need the next best available. Or a solution!

[Toms306]

A dry filter like pipercorss shouldn't affect the MAF....

[titch]

I had a pipercross panel filter and it killed the maf, i am back to a standard filter now.

[Jonny81191]

IMO:

Standard paper filters are fine for stage 1 or a "mild" stage 2 with a restrictive exhaust etc. For stage 2, they're wank. You can feel the resistance up in the revs, it just isn't as "happy" up above 3.5k. It'll still pull, but you're quicker changing up a cog.

Panel inserts are an improvement, and feel almost as good as a cone, much happier at the top end. BUT. K&N's need oil, oil (allegedly) kills MAF sensors. Therefore I'd question the point of fitting one over a cone.

I've recently got a clean (ish) cone from the breakers, no oil but I'm happy it's filtering well enough. Gains over the standard box are probably in my head, but it sounds nicer and is better than either of the options above, so I'm gonna stick with it for now.

If the MAF can be properly mapped out, then I reckon that's the way to go. If not, I'm gonna look into dry foam panel inserts, maybe do some flow tests if I feel it's worth the time.

Also, when I do a dyno run, I'm taking all my filters with me and intend to test the options to see if there's a power change, or more likely a power DELIVERY change, like I've said, it feels like the cone and K&N both let the engine rev more freely.

[weasle1uk]

Anyone tried a K&N Apollo?

[Poodle]

Most "uprated" filters are named for their flow capabilities, not the quality of filtering. I think a high-quality enclosed job is probably your best bet for a compromise, will have to pay for it though. :S Doesn't help that we don't know what's killing the mafs, some say oil, but then others have problems with dry filters...

I'd quite like to see alternative airflow sensing options tbh, the mafs on these are almost maxed on a stage 2 so would be good if there was something else we could fit and map in accordingly. I've heard repeated talk of map sensors, but it never seems to come to a conclusion, plus i don't understand it so can't help much there lol.

[Just Sean]

What about a maf of a higher powered pug/Citroen. 2.2hdi or the like?

Would it need to be mapped in or maybe plug and play?

[Piggy]

What about a maf of a higher powered pug/Citroen. 2.2hdi or the like?

Would it need to be mapped in or maybe plug and play?

even if it could I dont see what diff' it make.. its just a sensor...the diameter of the housing maybe bigger but the sensor is just a sensor...CMIIW

[Poodle]

The whole point is to get a bigger range from the sensor, if we're sticking to mafs then i'd expect it to have to come off something with at least another litre of capacity over ours, just to account for the substantial increase in airflow. Any sensor changes will need mapping in, otherwise the map calibrations and parameters will be miles out and we won't be able to take advantage of the expanded range.

Stick to your XUDs piggy, no sodding sensors to argue with there!

[cwspellowe]

The whole point is to get a bigger range from the sensor, if we're sticking to mafs then i'd expect it to have to come off something with at least another litre of capacity over ours, just to account for the substantial increase in airflow. Any sensor changes will need mapping in, otherwise the map calibrations and parameters will be miles out and we won't be able to take advantage of the expanded range.

Stick to your XUDs piggy, no sodding sensors to argue with there!

Exactly, fitting the sensor won't make any immediate improvement to the engine map, but the range of stock values means they can be used to tune engines above and beyond the normal stage 2.

It's like blown petrol motors using upgraded MAP sensors. If the engine tune is held back by stock sensor, the sensor needs to be replaced with one capable of giving the ECU values it can use.

For instance, a 2.0 MAP sensor can read x-y values, a 2.5 one could maybe read x-z, with z being a bigger reading than y. If you have a car tuned for higher manifold pressure than the 2.0 sensor can read properly, ie. higher than y, the 2.5 sensor is better for the application as long as pressure doesn't exceed z.

Slightly different sensor in question but the idea's the same.

[Just Sean]

Thats what my line of thinking was with the 2.2 maf.

I knew it would need mapping, but would the parameter settings have enough difference. Obviously a 2.0 maf is at trying its hardest at stage2 + but maybe the 110 hdi wouldnt have to struggle so much and would last longer, especially with a proven filter...

Somethign i might try when i go up and see dave

[Slam Wagon]

Would they bother putting a bigger sensor on the 2.2? Is it not within the capability of the 2.0 maf to still be useable on the 2.2? Its still nowhere near what your aiming for from a stage two so it would be fine to fit stock on a 2.2 so would they bother putting a better one on?

[Just Sean]

I suppose part number would be needed to see if they are different or not. If they fitted a bigger fuel pump then i would have thought the maf would be different.

Can Poodle use PP to find out part numbers?

What about bmw x30/35d's do they use mafs?

[Eeyore]

I swear I heard somewhere that the 1.6 HDI MAF sensor had a greater range?

[Mr Whippy]

Someone did a test years back where they ran standard, cones, papers, everything under the sun, and then no filter at all.

I think paper standard was 1bhp off no filter at all at 150bhp tune.


Standard air-box is an essential, it features ram air intake effect so at higher road speeds you get positive boost pre-filter, so it's as if there isn't a filter there.
It also feeds super cool air from the front air-dam, so again that is very beneficial.

I've seen cones in summer, even after driving for 5 mins, sucking in at 20deg above ambient. Even with that little duct pointing at the cone, it makes no real difference as hot air flows back from the radiator when moving and saturates the engine bay with 'warm' air totally offsetting the blow in from the OEM duct. When not moving there is no flow so it's still hot.

Ergo, 20deg ambient + 20deg = 40deg IAT.

So vs a standard airbox which is 20deg ambient + 2deg = 22deg IAT.

273 + 22 / 273 + 40 = 0.94 = 94%

So in theory with a stage 2 at 150bhp with standard air-box to a cone sucking in hot air, you get 94% of 150bhp, or 141bhp.


My pipercross panel even oiled/cleaned often used to have big particles evident post air filter, so I went back to paper. You have a MAF sensor and an expensive turbo down-stream!

K&N panel seem a bit better but not sure on filtration. Unless you clean/oil often (most don't), then it'll be letting particles through. If you do oil/clean often then oily MAF is probably gonna be an issue for longevity.


My 2p, save your money and stick to paper. Then spend the saved money on something that WILL benefit your performance. Like better oil, more frequency servicing etc...

If someone can show some numbers to prove a panel is better, despite it's obvious drawbacks, then I'll change my mind

Dave

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I swear I heard somewhere that the 1.6 HDI MAF sensor had a greater range?

The MAF sensor range is irrelevant really. The big issue is when it starts restricting flow too much. I expect it's an exponential efficiency falloff.

The function of that is more to do with physical dimensions more than anything (ie, fluid dynamics)

The standard airbox acts as a ram air intake at speed so you alleviate the issue of the MAF drag to some extent.


You also probably see the intake pipe down to the turbo itself acting as a restriction to intake flow before the MAF sensor I'd say. So changing the MAF might do nothing if that part is also starting to restrict you.



I think the late C5 HDi110's had a bigger MAF sensor (both physical and reading range calibrated)... I think.

I'd go look at something like a 123d BMW and see what power they run remapped, and how big their MAF sensor is, and if it runs based on the same signal return.


The best test really would be to test pressure in the pipe just before the turbo compressor intake (tap just before the bend where it's been straight for a bit)...

If it's positive, then don't worry about anything up to that point.

If it's negative, then work back to the airbox and see where it starts being negative!


Chase away the negative pressures pre-turbo and you'll get efficiency.

Dave

[Jonny81191]

If you've run tests, then why does the standard paper element feel more restrictive?

I'm not arguing any of what you've said above, but I can't ignore how different the engine feels with the cone over the paper filter.

With regards to the MAF, would it be possible to trick the ECU into thinking the MAF is giving a higher reading?

[Just Sean]

arguement isnt the restrictvness of the box vs no box. Its ruining mafs!

[Mr Whippy]

There is possibly a response benefit running a cone, but I'm not sure if it's just something you think rather than something that is really happening.

You can make a remap file that gives a big kick and feels stronger and faster, but a remap that feels slower can be 10% more powerful all over and get more torque sooner.

It sounds silly, but your senses can lie to you... I've done blind testing on customers before and often they want the 'inferior' remap because they think it's the faster one hehe.


That said, I'm not sure specifically on this issue.

You'd probably want to log throttle position and MAF flow rate at a high frequency (probably directly to a meter/logging gear, anything OBD would be too slow), and then plot the throttle vs MAF rate in tests from steady state > full throttle from varying rpms and stuff...

You'd probably see there if there was really any difference, or if a lot of it is just noise.


In my tests though, IAT soak stands out like a sore thumb. I only have to plug in the laptop and look at the ambient temp vs IAT and instantly know if they have tampered with the OEM airbox or fitted a cone.

So there may be plus sides to a cone, instant flow response, but the down-sides ARE visible and do impact the total power potential outright and possibly filtration issues will damage components long-term.
You also have to worry that the oily post-filter conditions might not be healthy for the MAF sensor.



I might have a go at logging the throttle vs MAF at some stage, but in my experience even if it were 50% better response (I've never felt it to be honest, but I'd happily get numbers to check), I still wouldn't want one due to the costs they incur which are obviously evident.


Each to their own though, it's just my 2p. When customers see the IAT logs vs a normal intake system they usually quickly go back to a standard air box!

Dave

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With regards to the MAF, would it be possible to trick the ECU into thinking the MAF is giving a higher reading?

The MAF values only really impact one map, and you can tweak the values in that map already. For any remap you ideally need to re-tune that map so in essence you correct for any MAF issues in doing that.

Dave

[Ruan]

Sorry, why can't we sack off the MAF and just go straight for MAP based past ~Stage 2 ish?

MAF sensors cause nothing but ballache, is it ACTUALLY working, half the time it's out of range, becuase HDis haven't got boost control, nor boost input, at WOT when the MAF sensor is out of range if the boost pressure isn't set exactly right, it'll smoke...

From MY experience of anything turbocharged, the response is massively improved the less piping on the air intake... Don't ask me why, but LENGTH of piping causes a massive difference... My XUD9 which had 2.25" piping from the compressor inlet all the way to out front, if I took OFF that piping, I could feel a noticable gain in top end power and a reduction in spool time... With it back on - less response/more lag... Let alone with a filter, I tried one of those BMC CDA jobs, I even tried an airbox off a Volvo D5 and it felt down on power, but I'd be fairly convinced that's a combo of the filter and piping...

Only way to have inlet piping IMHO is to have a full blown 3" inlet pipe with a massive filter - not necessarily a cone/enclosed £ra*e one... Just grab an airbox off a ~250hp petrol car, and you won't go far wrong...

The fact that the Stock air inlet pipe on an XUD9 is so MASSIVELY restrictive makes me think that a HDi will probably be not far off, after seeing one... I'd be inclined to believe that..

[Mr Whippy]

The XUD9 306 intake is not great, so no surprises that it can be easily improved. It was bad on the 405 and it wasn't improved far on the 306 really.

The 306 HDi on the other hand has a good intake.

Now don't get me wrong, the pipe down to the turbo itself might be a problem. BUT, until someone actually logs pressure at the compressor intake in normal road driving conditions you are just wasting money doing any mods.

It's important too to see the air intake as an entire system, not just a collection of parts. The ram air effect is well embraced in the 306 HDi intake, more so than earlier cars (XUD9) and later cars with the same engine (206/307 etc)

It could probably be improved by there would be risks as there are with any direct feed ram air system.

If you get positive pressure post air filter element, and still have some positive pressure pre compressor intake then you can pretty much say it's as good as having a big K&N stuck right on the front of the compressor of the turbo!



Not really sure what is wrong with MAF here. MAF in theory responds faster than MAP because MAF is sensing air flow in kg/hr (ie, what can actually be used to burn with fuel) and that value will go up in direct proportion to the compressor speed/efficiency.
MAP lags as long as it takes the post compressor side of the intake system to reach charge pressures set.

MAF doesn't go out of range easily. There is ample range for 300lbft at 2000rpm, and then out to 4500rpm with about 190bhp, and anything under those values and you are metering perfectly.
Throw in a late C5 MAF which seems to flow nearly 25% more kg/hr range before hitting a ceiling, so about 375lbft and 240bhp?!


Maybe if people are mapping them wrong or letting the MAF let it smoke, or letting the smoke map run out of range then yes... but as said you can run the standard sensor really far.
Now, it might be a restriction at 150bhp+ through fundamental fluid dynamic issues. But the problem there is the bendy concertina pipe and then run down to the back of the engine is also small so I can't imagine a bigger maf would do anything except cost you as you'd need to step down soon after to meet up with the OEM feed pipe.

And that is all irrelevant if there really is lots of spare positive pressure in the intake system.



Totally happy to see people prove OEM weaknesses and engineer better solutions, but from my experience there is no limit to MAF and it works just fine if you use it right.

As with everything on these engines, better so spend money on mods you need. At stage 2 the turbo is by far the biggest single cost to power. Just adding a good hybrid on the same fuelling adds 20bhp right away, such is the boost in efficiency! And that is before you then remap for the better efficiency!


I remember Pete mentioning intakes as something he wanted to look at, but before he did he was running 205bhp and 325lbft iirc on a standard intake and paper filter on his 206 HDi.
He *might* have run MAP but I'm not sure why... I have a feeling why but it might not be to do with performance so much as ease of mapping. Hmmm...

Dave

[Poodle]

I think Pete ran map because it made it easier to control the VNT properly..?

There's a late C5 in my local scrappy, fingers crossed it's still there next week! If it is i'll get some measurements for the maf.

I see your point about testing every last thing properly, but most people don't have that luxury; to do so effectively - without it being ridiculously labour-intensive - would require a four-post lift and a dyno at the very least, otherwise you're looking at days of work to test alternatives for just one item. We can make educated guesses about what is and what isn't restrictive, and without the tools mentioned it's often cheaper to just replace the part rather than to test exhaustively. For instance, i'd be very surprised if the inlet - turbo pipe turns out to not be restrictive, simply because of it's complex shape with small-radius bends and small cross-section. Testing it and its alternatives properly would take days (and we all know time is money) due to it's inaccessibility and methods for testing, the requirement for readings from several points in the inlet tract means either multiple runs are required for one set of data (more time) or you need several gauges (more money), both of which would introduce more scope for statistical variation, increasing the likelihood of spurious or inconclusive data... In an ideal world i'd be right up there with you, testing every last component to destruction in search of the perfect solution, but this isn't an ideal world. In reality, for the sake of such marginal possible gains, personally i'd be inclined to just risk it and spend the £20 for the replacement pipe.

Tbh i don't completely understand the difference between map and maf, or where this idea has come from that the maf's are nearly maxxed out at stage 2, anyone care to enlighten me?

[Just Sean]

I think that if we are busting them with too much air flow, I.e an open filter, where more.airflow is needed for s2+ that their must be something wrong with their parameters or effective working range. It must be us breaking them not faulty components. Some are even braking with panel filters on stage 1?

I am just after a solution to stop them going. Are they similar to the bottom pulley where the 306 one is a bad design but the 307 is better... Same engine, better components?

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Are the a lifed product? Should they be treated as consumables

[Toms306]

I don't see how you can break a MAF with 'too much' air, its only a heated wire at the end of the day that is cooled by the airflow over it, which allows a certain voltage to the ECU.

The MAF even has a 'clean' cycle at the start of each drive, it shoves massive current through the wire to burn off any crap. So it shouldnt be dirty (unless its getting oily from KN oil which won't burn off).

Now correct me if I'm wrong but the MAF fails because the hot wire gets thinner over time with all the heating and cooling, just like the elements a toaster. So its bound to fail over time - are you guys using brand new OEM replacement sensors? If not then you're using a part thats had years of use and is probably ready to fail anyway.

The only way I can see different filters killing a MAF is this - less filtration so more grit can 'hit' the hot wire as air is sucked through, which could be wearing it out quicker - that may be completely irrelevant though.


With the map sensor, yes I believe it would've been used to control the VNT, as they're used along side MAFs in VNT'd diesels. You can run without one without any issue except EML in a Golf for example though, as the MAF is more relied upon.

[Just Sean]

Is that all the maf is. Which makes it lifed! Can they be fixed then with a bigger gauge wire?

What your saying is tom with bad filters is erosion of the wire from the weather/shite

Will try and find out how much a new sensor is from pug today

[cwspellowe]

OR the filtration oil coats the element and unnecessarily cools it, causing false readings?

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Clicky

The above is a good read and actually a pretty bold statement by K&N. It doesn't rule out insufficient filtration as a cause of MAF failure but it categorically states that K&N filter oil does NOT contribute to failed MAF sensors. Not to say other brands or types of oil are different but they'd have to be 100% on their findings to make statements like this.

[Just Sean]

That would just make the car less economic. As when it goes, the car either goes into limp or feels like its got 5 HP!

Unless it goes dirty with oil and that causes it to send a signal to the ECU and puts it in limp mode... Can it be cleaned with spray on degreaser?

[Midnightclub]

Ever thought it might be a coincidence and nothing to do with that air filter, just that they're 10 years old + now, if people replace them i would imagine most would try a 2nd hand unit first.. Again another already 10+ year old part, much higher chance of it breaking again...