[agent008]

Hey folks, good evening. New "project" I had on the works.

I recently changed the oil for the first time since I bought the car and it was my plan to change the air cleaner at the same mileage as the oil and keep both as items to be serviced at the same time always.

But the engine air filter is not sold anywhere in Brazil which would mean importing a very inexpensive item and shipping and duties would end up costing more than the filter itself.


So I took a DDMWorks Mazda Miata aluminium intake tube kit I had bought and never used and pieced up a "CAI" (maybe I'll just call it AI) with a K&N oiled filter and found a way to fit the stock MAF sensor without needing the custom milled sensor "bung" to be welded into the intake. I used a VW MAF filter housing.

It's late here now, so I'll put the intake into the car and test it tomorrow. I believe it'll work well and maybe won't give me any troubles even using an oiled filter. The filter comes pre-oiled and the amount of oil on it is minimal, plus the MAF will sit quite a ways far down the pipe from the filter.

Tomorrow after testing if it works I'll report back here.

Here's the VW MAF housing, part # 06J.906.451:

 

[shabby]

Its better if the maf sits as close to the filter as possible, also whats the inner diameter of that filter housing? Is it similar to the stock one?

 

[TomatoSoup]

Our cars are susceptible to turbulence in the intake that messes up the MAF readings and the ECM then throws codes and can go into limp mode >>> Be aware!

(Some of the original aftermarket CAI's had this same effect.)

 

[agent008]

The VW MAF housing I have used has a 70.8mm internal diameter. The stock 2.4 MAF housing has a 69.4mm diameter. Both measured with he same caliper. What's you think, is a 1.4mm (0.55") in diameter too much of a change?
The intake pipes I used are 2.75" diameter.

Unfortunately due to wiring harness constraints the MAF sensor ended up quite far from the filter.

Here are a few photos. It is unfinished yet, I am missing one t-bolt clamp and have to get mounting tabs welded on to the tube. Father time being I secured the tube with a couple hose clamps bolted to the stock airbox and resonator bolt locations.
I might also cut the larger pipe a bit shorter and have someone mandrel bend it to the right angle, right now it looks a bit funny with the filter pointing up.

 

[TomatoSoup]

Ahh, I forgot yours was an N/A. You might well be OK with the MAF then

 

[agent008]

Ahh, I forgot yours was an N/A. You might well be OK with the MAF then

Thanks. I started the engine, let it warm up, and gave it a few revs, no codes.
It the weather is better tomorrow I'll take the car for a spin to see whether it will work well or not.

 

[HHGadget]

I have read on some old threads that the oiled KN filters were problematic

 

[JohnWR]

I have read on some old threads that the oiled KN filters were problematic

Mostly only if over-oiled, because the oil would get onto the MAF sensor and cause bad airflow readings.

 

[kgschlosser]

riv nuts baby!!!!

Get that plastic thing out of there and use a single piece of pipe from the throttle body to the air cleaner. 2 couplings and 4 clamps needed. This is how you do it.
Take 2 blocks of wood that are larger then the pipe when they are placed against each other. screw them together in a manner that will allow you to drill a 2.5" hole through the block with the center of the hole being the seam where the 2 blocks touch. Drill the hole. Unscrew 1 edge. using a saw or a belt sander cut a notch out of the edge that you unscrewed. you want to go all the way to the hole. then go another 1/2"

Take all of the screws out

Put the 2 block of wood around your pipe and align the notch with where you want to place the MAF. Screw the blocks together so it holds the pipe good and tight without crushing it. Now you can be inventive here on how you want to do this. I say if you have a high enough vehicle put the pipe and block of wood under the vehicle and a block of wood on top of the pipe where it is seen in the notch then a scissor jack on top and start jacking up the car. This will make a flat spot where the pipe is seen in the notch. I say to do it this way so that it's even constant pressure and it will give you a nice even flat spot. You can also use a block of wood and a 5lb hand sledge and that should also work but does have a higher chance of possibly coming out a little wonky.

Now that you have the flat spot cut the hole the MAF needs to be able to go into the pipe. Mark the holes for the screws. Drill out the screw holes making sure to get the chads/burrs off inside in the pipe. Don't want those getting sucked into the engine. Now put some riv nuts into the holes. You can not screw the MAF in place. The flat spot is flat so the MAF is able to seal properly and the flat spot makes it easier to drill and cut to get the MAF installed.

no welding needed!!!

if the wire for the AF are not long enough extend them. It is better to do that then to have the wires taught. The wiring harness is attached to the engine which moves around. one end of the intake pipe shouldn't move around all that much while the other end of the intake moves around as much as the engine. you could end up putting stress on the pins in the clip because of the MAF not moving arouns with the engine. That's if the harness has any tension on it.

 

[kgschlosser]

Also having the MAF where you do in the middle of a straight piece of pipe is the most ideal place to have it because the airflow will be as laminar as it can be. You do not want the MAF right after or right before a bend. Ideally you don't want it near any couplings either but you gotta do what you gotta do and the coupling is the lesser of 2 evils.

The name of the game with MAF sensors is straight smooth even flowing air with as little turbulence as possible.

There is a crazy pipe setup that can be done which will straighten the air damned near perfect, problem is it adds a heap of resistance.

 

[agent008]

@kgschlosser , your suggestion is great, but it is so involved and I would need time to source the pipe and have it mandrel bent.
Since my setup is not boosted I'm hoping to get away with the numerous couplings..? I know there's a higher risk of leaks/unmetered air entry but have used the highest quality couplings and clamps I could find. The 2 3/4" to 3 1/8" step-ups couplings were especially hard and I had to accept the red colour, non-smooth outer wall type as they were the only ones available.

If I were to leave it as it is the only things that I imagine would need to be done are to get the missing t-bolt clamp for one of the red couplings; cut off a small section of pipe near the filter end to leave the filter cone horizontal or pointing downwards; and improve the mounting by welding a couple tabs (even though the hose clamps I used left the pipe surprisingly firmly in place).

Regarding the MAF loom, I almost damaged it when I was tightening the mounting clamp near the hood hinge, I was tightening the clamp and did not look to the wiring, when I remember to have a look at it the wires were super taut. 😬 Fortunately the engine harness could be moved a little bit towards the driver's side giving a nice amount of slack back to the MAF loom. Now I'll just secure the engine harness so as to avoid it going back to where it was before so that it doesn't put tension on the MAF loom again.

 

[kgschlosser]

NAH you shouldn't have to source it. it's a single 45 degree bend. locating a 2' long 2.75" pipe that is bent at a 45 in the middle is easy to track down. I am sure there has to be tuner shop down in Brazil.

 

[agent008]

You're right KG, but come on, there's gotta be some value in me having done it all myself with what I had on hand 😁

EDIT: also the sound. The intake makes a ton of difference. From within the car it's almost like the engine increased in displacement. I loved it! Anybody with a NA looking for a more throaty sound with ease, just install a CAI. Well worth it!

 

[agent008]

Just reporting back here that the car threw no codes at all. Everything working perfectly and a great sound improvement.

 

[kgschlosser]

You did do a great job with what you had. It works and if you are happy with it then leave it as is. Only person your need to impress is yourself.

 

[marksbug]

just be sure the maf addaptor thingy has the same ID as the oe does. and it should be fine. there are $100 cai's on flebay with free shipping although I dont know how that works in your location. the air box on my coupe was smashed to peices when I got the car. I cut off what was left of the top so I could use the MAF section to clamp a cone filter to that and the oe rubber is still on there going to the TB. I do have aluminum to go on inplace of that, but no reason to put it on till the car is done and I cant fit everything as it should be. so if you find a broken solstice airclearner box,possiably any 2.4 ecotec top to cut off that should also do if the peice you have isant the right size and you cant resize it. but what you have should do fine if it's the same size. I made one in aluminum from the TB to the air box on my 06.( witch I took off to sell the car)that will probably go onto my coupe with a cone filter if I can stand the noise.

 

[agent008]

Hey all, I've got an update on this. Am about 200 miles away from home, drove here on the Solstice with the missus onboard. First trip after the intake change. So after about 180 miles, already into the city, i noticed a check engine light. Damn, I thought -- I was supposed to bring the VCX nano but didn't. So I scanned the codes on the Scan gauge II I have installed. Got a P0171, a search revealed it to be "system too lean". So either I have an intake leak or the MAF sensor is giving skewed readings due to the intake change. I didn't have a chance tu pull out the MAF to see whether it is dirty or oiled up. Will drive the 200mi back tomorrow very early morning and will be able to check the sensor after that only -- I'm on a tight schedule.

I reset the code yesterday and later on it came back. Today I filled up the tank with premium, my line of thought was that premium here has less ethanol so would accept a bit of a leaner mixture. Will drive the 200mi tomorrow and see whether the code will come back.

Has anybody had any past experience with a CAI and P0171? I especially don't want to run the engine lean to avoid internal damage... Any advice you might want to share would be appreciated. Thanks!

 

[kgschlosser]

the lean code is because of an air leak AFTER the MAF or the sensor is coated with oil from the filter.

 

[agent008]

the lean code is because of an air leak AFTER the MAF or the sensor is coated with oil from the filter.

Thanks, I'm on the way now, about 45mi on the premium fill and no code so far. I'll check the sensor when I get home.

 

[kgschlosser]

You guys do have a high ethanol content in your fuel down there don't ya?