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Discussion Starter · #1 · (Edited)
Anybody tried swapping out the OEM "suck-through" MAF with a blow-through MAF for placement after the turbo? I'm having trouble with turbulent air flow coming through the CAI extension to the air filter. I had to get rid of it, but having an open element air filter nestled beside a turbo is not a good thing.
 

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Re: Blow-Through MAF

do you still have the little mesh screen on the front of the MAF? thats what the screen is for is to help straighten the airflow so it can get a good reading.
 

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Re: Blow-Through MAF

Gary,

I've spoken at length with Joey on this same topic before and we disagree over two main points. He doesn't want to force people to lengthen the MAF plug wiring and I don't want the MAF located in the middle of a section of pipe. You just illustrated the reason why I do not like to locate the maf in the middle of the pipe.
It is not turbulence that is ruining your MAF readings, it is the laminar flow that occurs in a pipe of a certain length.
I am a proponent of extending the wires on the MAF plug and placing the maf into the fender with the filter bolted directly to it. The mouth of the filter must be as large as the opening to the maf in this case for best results.
The cone filter in the Ford Lightning pickup is ideal as it is short but has a wide opening mouth and can be screwed onto a piece of sheet metal that can then be bolted or screwed onto the mouth of the MAF.
This works much better due to the air being straightened out by the filter gauze and running at a lower velocity. As you can see, most MAFs have a bit of a horn shape on the front because they are meant to take air from the airbox in nearly every application and channel it into the housing.

Never mount your maf close to a pipe bend if you can help it.

One other thing you can do is use a larger piece of pipe leading to the MAF and place a MAF Screen in front of it like the ones used stock in the SVT airbox and mafs.

The reason your maf was reading funny is that any pipe leading to the turbo will have varying velocities across the cross section with the pipe center having the fastest flow down to zero at the pipe wall. These are measured with a velocity profile or cross section of the pipe. The fast flowing air in the center will create more draw through the sampling tube than is truly representative across the whole pipe. Fluctuations in engine rpm will affect this, as simple a thing as intake reversion from valve opening events will cause stuttering in the MAF signal.
Also Any bends in the pipe will shift that velocity profile towards the outside radius of the turn. Even in a blow-thu configuration a screen must be used to spoil the laminar flow of the air going through the pipe.

If you've got to have something to spoil the airflow then it might as well be the filter itself rather than having another piece in the pipe IMO.
 

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Re: Blow-Through MAF

I'm running a blow through setup on my supercharger kit without any issues.

You can try rotating your MAF to get a better reading. You will get different readings depending on how it is rotated. You'd like to get a reading that represents what is actually getting into the engine. Moving it to a new position as Warmonger mentioned above would be the best solution.
 

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Discussion Starter · #5 · (Edited)
Re: Blow-Through MAF

You can try rotating your MAF to get a better reading. You will get different readings depending on how it is rotated. You'd like to get a reading that represents what is actually getting into the engine. Moving it to a new position as Warmonger mentioned above would be the best solution.
Yeah, I tried rotating it, but that did not help. It wasn't until we removed all piping to the MAF that we discovered that the problem was in fact the flow of air as it entered the MAF. Apparently, the final pipe bend was too close to the MAF. The pipe diameter was also much smaller. Without a proper transition, the air largely dodged the MAF sensor altogether.

warmonger said:
I am a proponent of extending the wires on the MAF plug and placing the maf into the fender with the filter bolted directly to it.
...
One other thing you can do is use a larger piece of pipe leading to the MAF and place a MAF Screen in front of it like the ones used stock in the SVT airbox and mafs.
Tom, thanks for confirming our suspicions. My friend, Joel, also suggested I try inserting "honeycomb" in front of the MAF to smooth out the air flow, but it wasn't available. Using what we had on hand, Joel suggested we try another option, which we partially implemented: keep the MAF in its stock location, attach a short, conical filter directly to the MAF, enclose the MAF in a heat shield, and then run a "ram air" setup to it from the fog light. Before you start tweaking my tune, let's decide on an induction configuration. Which setup would you prefer I use? Should I pick up a Lightning MAF and filter and stuff them both in the fender?

BTW, I like the trick you describe in Trevor's thread for preventing boost leakage at the IAT. Gonna have to look into that!
 

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Re: Blow-Through MAF

I don't have anything to add as it sounds like you and your friend have a good plan figured out. :cool: Making a cold air chamber with plenty of air inlet should work just as good as a fender mount and it has the added advantage of reducing the distance the air has to travel between the maf and the throttlebody inlet.

Go with one or the other though since your car has been more sensitive than most to maf orientation.
 

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Re: Blow-Through MAF

I was under the impression you had the mesh screen in front of the MAF this will create the turbulance needed to disperse the air evenly. This I would try first and then reset the PCM so it can relearn the calibrations. Also GAry I have a 3" intake I can send you no charge to try. I have it welded up ready to go the sizing on the 3 liter maybe more critical due to the airflow increase over the stock 2.5 liter. I like to try that next I will send it no charge. JOey
 

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Re: Blow-Through MAF

you shouldn't need to extend the wires. the MAF can reach to the fenderwell easily . well i know mine fit well with the move
 

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Discussion Starter · #9 ·
Re: Blow-Through MAF

I was under the impression you had the mesh screen in front of the MAF this will create the turbulance needed to disperse the air evenly. This I would try first and then reset the PCM so it can relearn the calibrations. Also GAry I have a 3" intake I can send you no charge to try. I have it welded up ready to go the sizing on the 3 liter maybe more critical due to the airflow increase over the stock 2.5 liter. I like to try that next I will send it no charge. JOey
Thanks for the offer, but before you send that out, we need to confirm that the bends of the pipe will work. The issue I had was the result of both pipe diameter and pipe bends. Maybe we can try that out when I come out to visit. ;)
 

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Discussion Starter · #10 · (Edited)

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Re: Blow-Through MAF

I know we had problems with mine, but once Tom realized what was going on, he nailed the tune ... thanks to my video showing the thing going pig rich ... you definitely NEED a wideband O2 gauge to help tune.
 

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Re: Blow-Through MAF

Tom, would this be a good time to pick up a Lightning MAF, adapter, and air filter? Do you have the 90mm MAF transfer function? I think it was Reebs who told me he had trouble getting it tuned. The link below offers an excellent price on the MAF & adapter. Where is a good place to get the "shorty" air filter?

Ford Mustang/Lightning 90mm MAF & CNC Adapter - $99.95 : Lightning Force Performance
I can tune in a 90mm but it will be just like starting over. Right now I'm willing to tune you in on the MAF you have. What's wrong with it, is it not working now?
 

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Discussion Starter · #13 ·
Re: Blow-Through MAF

I can tune in a 90mm but it will be just like starting over. Right now I'm willing to tune you in on the MAF you have. What's wrong with it, is it not working now?
no, nothing wrong with it. it's my third OEM MAF. i figure if i gotta pay $150 for a MAF, it might as well be an upgrade. plus, since i'm back on your base tune anyway, i thought we actually were starting over? in which case, this would be the time to make any additional changes before you tweak things. if i'm mistaken here, i apologize.
 

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Discussion Starter · #14 ·
Re: Blow-Through MAF

More insight from Tom, minus personal matters:

warmonger said:
Gary,

With either maf we're going to have to tune you in again. So now it is just a matter of which maf do you want to use? We both know how fun it is with the 3L turbo and as soon as you start breaking 10psi or so you're going to want the bigger maf, period. So given you are looking at a new maf then we can work something out and supply you with one. Joey and I have been getting ready to move to the 90mm mafs and we have the adapters for them already. We are making a custom screen for the maf at the inlet so that when the maf is mounted into a pipe or even with a filter on the end of the adapter it should read smooth airflow and help eliminate these issues, or so we think.

The MAF outlet should be about 3.5" for which you can use a 3.5-3" reducer going to 3" pipe Before the inlet you really need to expand it out, you can have a piece of 3" pipe expanded outward at a muffler shop and then use a coupler to bolt to the maf adapter. As long as there are no bends within about 5" of the MAF, and the pipe is expanded the last couple of inches before the maf, then it should work. The screen should help with this. In my opinion the best method would be the cone filter that normally fit the lightnings, they don't use a clamp they fit inside the airbox and when the lid is clamped down they seal. You can use a piece of sheetmetal that is circular the same outside diameter of the filter, then cut out a maf inlet hole that is the same as the widest diameter of the maf inlet. this allows already straightened airflow to flow right into the maf. A screen will still help for very low speed air but you won't necessarily need it. If it is in the middle of pipe I think you almost have to add a screen.

There is another factor coming up, in just a few short weeks I'll be on my way to Iraq and there will be a delay between when I can get back to working on tuning for people.
 

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So Gary,

What did you end with ?

That intake pipe from maf to air filter is my last piece to put on.

Works good with only the 90mm MAF.

Behaves a little bit different with the pipe on.

Did you manage to find a solution ?
 

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I currently fixed my idle issues running the 90mm maf,I relocated it to the fender well and extented the Maf wiring about an extra foot. I ran 4'' plumbing behind it and best of all "no screens''. I'm gonna be gettin it tuned again,hopefully the last time on thursday:banghead: Driveability is just like when I had the screens in,but there is no slight power loss. Definatly the best way to run this maf with good results.
 

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I currently fixed my idle issues running the 90mm maf,I relocated it to the fender well and extented the Maf wiring about an extra foot. I ran 4'' plumbing behind it and best of all "no screens''. I'm gonna be gettin it tuned again,hopefully the last time on thursday:banghead: Driveability is just like when I had the screens in,but there is no slight power loss. Definatly the best way to run this maf with good results.

So thats air filter directly on the maf in the fender well right ?
 

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Discussion Starter · #19 ·
I ended up not using the cold-air extension. When the extension was between the air filter and the MAF, it threw off the MAF sensor. I currently have the air filter directly connected to the MAF, and that works fine. If you want to use the cold-air extension, I recommend doing what BadassCougar describes above: installing the extension after the MAF rather than before it. Warmonger suggested I do that if I wanted to use the extension.

P.S. Feel free to send me a PM if you want to get my attention. I don't really hang out here.
 

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FYI if you have idling issues running a CAI or any bend before the MAF usually it's because the sensor isn't getting a good air sample reading after the bend. Moving the sensor before the pipe is a good idea but you can also try to rotate the MAF sensor in the mean time so it will pick up a better reading. I've never had issues with my GMK cold air intake but I used to have a SCA air intake back in the day and a slight MAF rotation fixed a stalling issue I was having.
 
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