Subaru WRX Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
32 Posts
Discussion Starter · #1 ·
Is there anyone on here who has attempted, or knows someone who has attempted to relocate the stock MAF/Intake Temp sensor to a post-intercooler location? My thought process here is that I should be able to get a much more accurate MAF value based on what the engine is truly getting into the intake.
I understand that this would require extensive MAF rescaling as well as a recalibration of the temperature compensation tables, but my main concerns are:
- Turbulance: Will the air flow post intercooler be too turbulent to get consistent MAF readings? Or is the end tank of the intercooler enough to smooth out the air flow.
- Data Processing Delay: Has relocation of the MAF been known to cause problems because the computer cannot compute fast enough to get the right fuel mixture? My first thought is that this would require adjustment of the Tip-in values, but if the data isn't analyzed fast enough I'm not sure that would help all that much
- Sensor Damage due to Boost: My first thought is that the sensor elements themselves shouldn't be significantly effected by any higher pressure air, but what about the housing? Obviously it was not designed for this, but has it proven to hold up in the past?.
- If I decide to go the speed density route, is there a way to disassemble the Temperature sensor from the MAF? Is the stock intake sensor accurate enough to provide good Speed density readings?

Anyone who has any experience with this or similar applications please let me know. I'm looking for the die hard DIYer's and home brew tuners who enjoy the feeling of creating something truly unique for their vehicle

Thanks
 

·
Super Moderator
Joined
·
11,451 Posts
With all that work why not just air speed density.

Sent from my SAMSUNG-SM-G935A using Tapatalk
 

·
Master Baiter
Joined
·
12,651 Posts
Do you have a FMIC?
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #4 ·
With all that work why not just air speed density.

Sent from my SAMSUNG-SM-G935A using Tapatalk
I mentioned I could do that, but the questions still apply to moving the temperature unit

I am currently running a Process West top mount. I am guessing this would be a whole lot easier with a FMIC
 

·
Premium Member
Joined
·
6,716 Posts
Is there anyone on here who has attempted, or knows someone who has attempted to relocate the stock MAF/Intake Temp sensor to a post-intercooler location?
I mentioned I could do that, but the questions still apply to moving the temperature unit

I am currently running a Process West top mount. I am guessing this would be a whole lot easier with a FMIC

Blow through setups are notoriously difficult to tune and almost always never work out well. Turbulence is a big problem and you just don't get consistent readings.

For speed density you will want to install an aftermarket IAT sensor in the intake tract, close to the engine. The most common location is in the cold side charge pipe, a few inches before the throttle body. That's where I have mine for speed density.


To be honest, I don't even know how you would do a blow through MAF with a TMIC.. you need a blow through boost tube placed in the charge pipe that is larger diameter than the conventional charge pipe size. Since TMIC setups don't have any charge pipes, there wouldn't be anywhere to put the MAF. You could tap the intercooler for a relocated IAT sensor though.. or install it in the manifold, but I'm not sure that would get the best readings. It would be slightly advantageous to put an aftermarket IAT sensor post intercooler in a draw through MAF setup (and extend the OEM wiring from from the MAF to the new IAT sensor. You would get better readings as far as what's actually entering the engine.
 

·
Master Baiter
Joined
·
12,651 Posts
You can't relocate the MAF without a FMIC setup. As brought up by Robin above, even then, it's not ideal. Before speed-density tuning was offered on something readily-available like Cobb AP, it was an option, but there's absolutely ZERO reason to run a blow-through setup now.

If you want to tinker with the OE MAF setup, tap the PW TMIC for IAT and be done with it. If you're worried about MAF readings and their accuracy, go speed-density.

That said, there really isn't a reason to go SD until you're maxing out the MAF sensor. You won't get a better / more powerful tune with it; it's simply a different way to skin a cat.
 

·
Super Moderator
Joined
·
11,451 Posts
On this topic, what advantages would this have? What situation would make this an option over stock maf location? Is there any reason to do this over a speed density setup?

Sent from my SAMSUNG-SM-G935A using Tapatalk
 

·
Premium Member
Joined
·
6,716 Posts
On this topic, what advantages would this have? What situation would make this an option over stock maf location? Is there any reason to do this over a speed density setup?

The advantage would be that it won't be maxed out where a big MAF in draw through configuration would. You can increase the diameter of the MAF to a point, but too big and you can't get good readings because there will be too much turbulence and variation in flow. Since the air is already compressed in a blow through setup you can use a smaller diameter MAF housing and still be able to get a usable reading out of it. If your setup is moving so much air that it's maxing out a big MAF housing in stock location you're going to have to figure out another way to meter air.. that's where blow through came in back around 2004-2006.

The only reason I can see to use blow through over speed density is if speed density tuning isn't an available option for the ECU you are using.
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #9 ·
Thanks guys, it was just an idea I have been playing around with in my head and wanted to bounce off some other people. I live in Phoenix, and between the 120deg summer afternoons and 30deg winter mornings, I have 4 different seasonal MAF scales that I use, my hope was that a post intercooler temp sensor would allow me to adjust my temperature compensation tables more accurately, reducing the number of maps i have to keep updated, and lead to more consistent fueling
But it sounds like we all have the same concerns; so the SD route will probably be the next one to take.

Any recommendations on an aftermarket temperature sensor?
 

·
Æternum
Joined
·
15,864 Posts
Thanks guys, it was just an idea I have been playing around with in my head and wanted to bounce off some other people. I live in Phoenix, and between the 120deg summer afternoons and 30deg winter mornings, I have 4 different seasonal MAF scales that I use, my hope was that a post intercooler temp sensor would allow me to adjust my temperature compensation tables more accurately, reducing the number of maps i have to keep updated, and lead to more consistent fueling
But it sounds like we all have the same concerns; so the SD route will probably be the next one to take.

Any recommendations on an aftermarket temperature sensor?
FYR, you can actually re-pin the IAT sensor and move it to your TMIC cool-side. I was strongly considering this for my bugeye. I think I looked at a BOSCH sensor.

You don't need to convert to SD to do this.
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #11 ·
FYR, you can actually re-pin the IAT sensor and move it to your TMIC cool-side. I was strongly considering this for my bugeye. I think I looked at a BOSCH sensor.

You don't need to convert to SD to do this.
I'm not sure if you could really do this, as you would be using post-IC temperatures to compensate for pre-turbo measurements. During cruise, not really an issue, but I could see a potential problem after periods of heat soak, where the temps at the MAF would actually be lower than the post-IC temps for a significant amount of time.

But I may still try it.
 

·
Æternum
Joined
·
15,864 Posts
I'm not sure if you could really do this, as you would be using post-IC temperatures to compensate for pre-turbo measurements. During cruise, not really an issue, but I could see a potential problem after periods of heat soak, where the temps at the MAF would actually be lower than the post-IC temps for a significant amount of time.

But I may still try it.
You need to re-tune your tables, yes.

Sorry, I should have added that an ECU remapping is necessary.
 

·
Premium Member
Joined
·
6,716 Posts
I'm not sure if you could really do this, as you would be using post-IC temperatures to compensate for pre-turbo measurements. During cruise, not really an issue, but I could see a potential problem after periods of heat soak, where the temps at the MAF would actually be lower than the post-IC temps for a significant amount of time.

Lots of people have done it.. like I said before, you get better readings of what the actual air temperature is as its entering the engine that way. If you have substantial heat soak it will be better to be measuring IATs post intercooler. When you have the IAT sensor in the stock location it will think the incoming air is much cooler than it actually is since it won't be accounting for the heat soak.
 
1 - 14 of 14 Posts
Top