Air Intake Upgrades and MAF questions.

[shizzler]

Hi all,

Just tackled a full intake system upgrade over the weekend. Since I'm too cheap to drop hundreds of bucks on plastic air ducting from euro vehicles or R32s, etc, to pull off the full upgrade, I customized a few things. Figured I would share.

Started with the PD150 pipe that I picked up off the classifieds here. Thanks again bazmcc! Since the aluminum pipe has to run around the exhaust manifold and EGR cooler at a clearance of only a couple inches, I decided to give it some heat wrap. Looks like I should have bought more then 15'. Oh well.

PD150 pipe vs. stock 2003 ALH pipe.



After cleanup and heat wrap:




Pipe installed:


Might as well take a quick look at intake clogging before replacing upper intercooler pipe elbow: I think I'm still ok for now...


Next, I knew I didn't want to bother installing a T.I.P. that starts at 3" diameter only to run a 2.5" intake up to it. So I grabbed a VR6 air box and 3" MAF housing off the vwvortex classifieds. I then realized that the R32 snorkle is ridiculously expensive and hard to find. The PD150 flex pipe from MAF housing to t.i.p. is also pretty stupid at $80 for a 6" long pipe. So, what to do? I bought a cheap 3" flex pipe intake hose kit online (only to later see it for a few bucks cheaper at my local auto parts store, doh).

Bought a hole saw, got the air compressor and die grinder fired up, and started buzzing away at the VR6 air box:


Tried to smooth out the upper lid also, but it was just too much work so I called it ok at this point:


New lower air box in place.




Everything assembled:



Now, swapping over the MAF sensor! What a pain. I bought a set of torx security bits to remove the sensor with its damn custom screws. WRONG! Its a 5 point star security bit. Who the heck has one of these anyway. So I vented my annoyance by drilling the screw heads off. After this, I went to pull my stock ALH MAF sensor out of its housing.... but it was kind of stuck. When it finally let go and flew out, I noticed something kind of odd. There was a little diagram and a couple of small connections to hold a resistor (I think?) but there was nothing there. Since my car was running awesome before I dug into this mod, it probably flew off when I yanked it out. What is the resistance of this little guy? Can I just replace it with something from radioshack?

Heres a pic, the original ALH MAF is on the bottom (obviously):


So when I bought my MAF housing from someone on vwvortex, I did not expect to find a sensor it in, but when I opened the package, there it was. bonus! I figured it must have been a dud or something for this guy to just "throw in" a $150 sensor.

Now, I reassembled everything with my original ALH sensor, wondering if perhaps there was never a resistor there in the first place. The car ran like crap.... so there must have been. Decided to take a chance on the VR6 sensor, and, well, so far so good! I notice that the part numbers stamped on there and identical, but the resistor "letter" is different (E vs K). Does this matter? Are they in fact interchangable? Tuning gurus, I would appreciate your input here.

My car was running a little rich since the PP520 install and no IQ adjustment. I don't know anyone with a vag-com. So I was hoping this 2.5" to 3" MAF housing swap would lean me back out a little. Still have some smoke haze at WOT, but the idle stumbles seem to be ok. Would the VR6 MAF sensor giv e calibrated output for the 3" housing already? Or does the sensor output just get interpreted different by the engine calibration?

So, happy to have any comments, and those in the know please fill me in on the MAF issue! Thanks.

Oh yeah, cost breakdown:

PD150 t.i.p = $180 shipped (have since seen them cheaper)
VR6 air box = $25 shipped
3" MAF housing (and sensor!) = $20 shipped
3" Flexible air duct = $25
15' of 1" heat wrap = $15

Total cost of full 3" (sort of) intake system = $265. I'm pleased.

[shizzler]

One more pic. Mods, the 10 picture limit per post is dumb. Is there any evidence that this is really saving bandwidth?

[Rub87]

you don't need a resistor there, it's used on the V6 tdi models as some gassers, it's not just a resistor, it's a "thermister", it is used to measure ambient air temp..

For the rest it's looking very well imo, good upgrade

if i were you I'd install a racepipe, seems the biggest restriction.. or gut the stuped egr valve out..

[shizzler]

Originally Posted by Rub87

you don't need a resistor there, it's used on the V6 tdi models as some gassers, it's not just a resistor, it's a "thermister", it is used to measure ambient air temp..

For the rest it's looking very well imo, good upgrade

if i were you I'd install a racepipe, seems the biggest restriction.. or gut the stuped egr valve out..

A thermistor! That makes more sense, thanks.

Ok next question though is why the car ran crap on the original ALH MAF sensor and then runs great using the VR6 MAF? In my mind this must be related to the sensor calibration relative to the housing size; i.e. the VR6 MAF is made for a 3" housing and my ALH MAF is meant for its original 2.5" housing. So the sensor is application specific then....?

Otherwise thanks, EGR is staying intact though.

[Rub87]

yes, the alh one will read to low in the bigger pipe..

[TDIinTexas]

The car will be "laggy" until you remap the ecu. When I switched over to the R32 housing it ran like a turd until the air tables were adjusted to compensate for the larger diameter housing. The ecu is seeing a lower volume of air flowing through the maf and is laggy because of it. Larger diameter equals slower air, when you remap you can then really take advantage of a larger opening.

I didn't forget about your pictures, but I sold my 17/22 turbo today and spent all day swaping it over to the new owners car, and putting a vnt-15 back in mine for the time being. Its time for a big boy turbo now!

David

[Savage Diesel]

Please let me know how it does in the rain.

You might want to drill a couple of small water drain holes in the new intake pipe.

My fear of doing that airbox mod without a water separation chamber is water mist soaking the paper filter. A wet paper filter will not flow much air and it becomes very structurally weak from being wet... the perfect situation needed for the turbo to tear out pieces of the wet paper filter from the vacuum draw.

I suspect this is why there are a couple of heavy screens in the MAF housing... to help keep paper chunks and debris from being ingested should the air filter fail.

So keep us posted on how it works in heavy rain... maybe check the filter afterwards too...

[TDikook]

Originally Posted by Savage Diesel

So keep us posted on how it works in heavy rain... maybe check the filter afterwards too...

Yeah spoken like a true........what ever you are Mike there you go .

and this makes me cringe and reminds me of watching LurkerMike tape up his hose he bought from Orielly's. the corrugated hose,, Make sure that the ends around the rubber end pieces are air tight. thus the reason Mike electrical taped it up, but at least it was in good effort. if the connections are cheap, I assume the probably are, there is a possibility that debris can get into the pipe, which is UNFILTERED. that is bad. make sure the connections are air tight. we might have made fun of mike, but he was being preventative.

Eric B

[Rub87]

Does anyone know what would be maximum level of vacuum you should measure after the filter?

I measured around -0.1 bar at mine in the higer revs at full load.. it's a filter from mitsu carisma TD, 90hp stock or so

[shizzler]

Originally Posted by Savage Diesel

Please let me know how it does in the rain.

You might want to drill a couple of small water drain holes in the new intake pipe.
......
keep us posted on how it works in heavy rain... maybe check the filter afterwards too...

Funny you should mention that. I woke up this morning to find it pouring down rain, and had to drive through it rather spiritedly to get to work on time. For the entire 20 minute drive I couldn't stop thinking about how I neglected to add a couple water drain holes at the low bend in the pipe before it gets to the air box. I am going to pull it apart and add a couple small holes. It's probably got a puddle of water in it right now.

However Mike, I am reasonably sure that the metal grates before the MAF sensor are there simply to smooth and straighten the flow for accurate metering.

Tdikook, I know what you mean about the cheap piping, I had to analyze it for a while to feel totally comfortable running those connections after the filter and MAF. The flex tubing is spiral wound, and threads into the connectors. They screw several threads in before bottoming out and feeling really firm. I suppose I could always lay a bead of silicon in there and tighten them down for good. But they seem ok.

Kind of rushed to get this whole job done, seems there are a couple aspects I didn't fully consider. But it's all easily fixible.

Thanks for the comments everyone.

In any case, the engine is running really nice with this mod (using the VR6 MAF sensor). Feels like a decent bump in mid-range response and power, carrying through all the way to the top end.

[shizzler]

Well thanks a lot Mike, spent all afternoon worrying at work before finally going to leave and checking the pipe first. Bone dry, somehow.

But the upper MAF to PD150 t.i.p. piece was loose! balogna!

I quickly pulled the air box out just now to poke a few small drain holes in the low bend, and then laid a bead of silicone in the rubber connectors. They were a lot tighter before I thermal cycled them a few times.

[Savage Diesel]

Originally Posted by shizzler

Well thanks a lot Mike, spent all afternoon worrying at work before finally going to leave and checking the pipe first. Bone dry, somehow.

But the upper MAF to PD150 t.i.p. piece was loose! balogna!

I quickly pulled the air box out just now to poke a few small drain holes in the low bend, and then laid a bead of silicone in the rubber connectors. They were a lot tighter before I thermal cycled them a few times.

Always better safe than sorry...

BTW, I used the same ~$20 hose on my car to connect the VR6 MAF to the air pipe... Spectra brand from O'Riley's but other chain stores sell it too.

For the record, I appreciate you trying this and reporting back on your results. I will consider it an option now that you didn't have issues in the rain. The R32 deal will look factory, but I don't know if its cross-section is really that big of an improvement... at least as compared to what you did...

[Rub87]

Originally Posted by shizzler

... They were a lot tighter before I thermal cycled them a few times.

Yes, but usually after the night they're tigher again.. Altough this gets worse with the age I think .. physics..

[shizzler]

Well my scan gauge has officially gone crazy.

Yesterday driving to work in the pouring rain it was reading in the 30s to around 50 mpg and gave a trip avg of 44. Prior to this intake mod it was reading average trips of around 60mpg (repeatbly, but obviously not correctly recalibrated since adding PP520s and getting new tune). So at this point I am thinking, bummer, this MAF sensor must be causing me to overfuel a bit.

Then after siliconing the upper MAF to tip pipe last night, this morning the scan gauge was reading 80 to 100 mpg! wtf.

Engine calibration is unchanged, only perhaps in its response to the MAF readings. The car was running smooth and strong both yesterday and today. I can't imagine a tiny air leak around those crappy rubber connectors could cause fueling differences like this. For that matter, cruising on the highway, I had similar boost levels each day. With a similar boost, its going to take a certain amount of fuel to make the right amount of power to maintain speed. So why would MAF readings change the scan gauge mileage calculation? I thought it was only based on actual fueling?

Either something wierd is going on or this mod just netted me 40 mpgs....

[Savage Diesel]

The MAF is some kind of "thin film" deal... I wonder if the silicone "poisoned" it with the curing vapors?

Or if you flow characteristics are so vastly different now that the calibration is just waaaaaaay off?