Can I get rid of the MAF in my STI and just wire in a intake temp sensor into the intake going to the turbo? Or is it better to tap it rite into the manifold..Thanks

You could get rid of the MAF, but you'll need to know the type signal the MAF sends to the Hydra. I'm not sure that its a simple thermocouple signal, but if it is, those are cheap to buy and easy to install in your intake. www.omega.com has tons of different ones. I'd pick a Type that corresponds to the stock MAF one. Type K is the most common.

Can I get rid of the MAF in my STI and just wire in a intake temp sensor into the intake going to the turbo? Or is it better to tap it rite into the manifold..Thanks
Some people have put IAT sensors on the intake manifold or used a JDM manifold that already has an IAT sensor on it. Ask Phil. He should know since he's not using the maf on his car. I plan on doing the same same thing so I can use post intercooler temps. I think I remember Darth say that he runs a JDM manifold with the IAT sensor.

so I guess a regular ford/chevy intake sensor won't work? Also would anyone know which wires to use?

so I guess a regular ford/chevy intake sensor won't work? Also would anyone know which wires to use?
I'm sure it could be made to work but the question is: What is better/easier? I wish I had the answer since I plan on doing the same thing but my attention has been focused on getting a new tranny so I can aleast drive my car.

I'm still looking but it seems the WRX/STi IAT sensor is a 5V thermoresistor. The Hydra would measure current running through at 5V.

You would need to run it into the same MAF connector in the engine bay, but thats a matter of figuring out the pinout of that connector.

http://www.innovatemotorsports.com/forums/showthread.php?threadid=255

Good read on basics of IAT; the best I could find.

The one they mention from DigiKey is $2.83. You can't beat that. There are only 13335 left, so hurry out and get one. www.digikey.com

Here are the key things you need to know:
1) input voltage (I believe it's 5V for ours)
2) thermistor resistance rating (the above is a 2.2 kOhm resistance, NTC)

Be sure you get these two right or the Hydra won't know what to make of the temp (voltage drops as resistance goes up and temp goes up (NTC)). Also, I have reason to believe that the IAT data may be used to set the wastegate duty as well as fuel trim. With two parameters in the mix, getting it right will be important.

As far as the MAF pinout is concerned, I can't find any info on which wires run to the thermistor. I may cut my dead MAF open and tell you later.

Talked to Andrew today..A Chevy IAT will work fine..

The GM IAT is the one you should use but keep in mind you will most likely have to retune the "Intake Air Compensation" maps for both fuel and ignition. It may only be minor if you run the sensor before the turbocharger.

I've had very good luck using the factory MAF sensor without the limitation of the stock housing (3.5" intake) but a post turbocharger IAT is always better. It will have to be tuned.

If you've never tuned the Element Hydra system, I would advice you first use your MAF and then upgrade later.

Thanks,
Phil
www.elementtuning.com

Phil, can you detail this? Did you make a custom larger turbo inlet pipe, and then just mount the stock maf in it?

Thanks,
Mullet

The JDM intake manifold does come with a IAT sensor in it, and as far as I can tell, reads exactly the same as the sensor on the MAF. I took both of them off the car, and laid them in my garage.. and then measured the resistance on both. Identical. Then I put both of them in my refrigerator (what's for dinner? Its not beef!) and again... identical.

I've been running the JDM intake/IAT for a few months now, and its worked very well. I've just got vampire clips on the stock maf harness leading to the sensor.

What I HAVE had to adjust is the fuel compensation for temperature differences. The temps inside the intake seem to be "smoother", not near as jumpy as at the MAF housing. Makes sense - intercooler, turbo, hot engine, etc.... all of that smooths the huge changes you would normally see.

Just made sure, whichever sensor you go with, is a fast reacting one and that you get it calibrated correctly.

Where on a JDM intake manifold is its IAT sensor? I assume you meant to say throttlebody assembly?

No, the V8 intake manifold has a seperate IAT sensor, right under the throttle body. Next to the PCV valve.

Oh. Hm.

V7 spec C cars had this sensor under the intake manifold. It is used by the ecu for the IC water spray. I wonder if the US STI has one as well. If thats the case you can buy that sensor at the dealer.

Clark

Thanks for the info; I must have missed this post. :)

hey, who's got a part number for this jdm sti iat manifold-mounted sensor???

OR, who's got a spare one from a pull?

ken

From my understanding most ended going back to the "bolt the MAF in the fender" mod. The intake manifold sensor would heat soak and take too long to register the colder air after the car had been sitting at idle. I've been running the MAF in my fender well for years and have never felt the need to change. Also I have configured the IAT correction tables to work in this orientation. It's similar to the intake temps you would see from a cold air intake.

Thanks,
Phil
www.elementtuning.com

From my understanding most ended going back to the "bolt the MAF in the fender" mod. The intake manifold sensor would heat soak and take too long to register the colder air after the car had been sitting at idle. I've been running the MAF in my fender well for years and have never felt the need to change. Also I have configured the IAT correction tables to work in this orientation. It's similar to the intake temps you would see from a cold air intake.

Thanks,
Phil
www.elementtuning.com

But how do you mount the maf sensor in the fender when using a turbo with a 4 inch intake without restricting things?

or does one just get a maf sensor 'flange' welded into the side of the 4 inch intake piping??

You dont J.

Clark

But how do you mount the maf sensor in the fender when using a turbo with a 4 inch intake without restricting things?

or does one just get a maf sensor 'flange' welded into the side of the 4 inch intake piping??

From what I am gathering, you just bolt the sensor itself in the fender (no pipes involved) and this gets ambient air temps. I worried about this at first thinking that the MAF would go bad being exposed to debris, but now I realize that the maf sensor and the IAT sensor are two different things. And the IAT part of the MAF/IAT sensor is more rugged and has lasted in many others applications. Just let 'er breathe free if you have a MAP based ecu

I am surprised that so many people would mount their IAT sensor in the engine bay. At high engine loads/speeds i would imagine the IAT sensor would read lower due to all of the convective cooling of the air at high speeds. But the actual intake temp of the air would be higher due to the turbo compresssing the air. Wouldn't this actually make the correlation work the wrong way? I guess a really good intercooler would go along way to evening the gap but it kind of takes the logic out of the correction imo.....

Sorry if this sounds flippant, but there's no point in discussing this any further until someone has figured out a fast-reacting IAT solution for mounting at the intake manifold that works with the Hydra properly.

The maps Phil made are for the stock MAF/IAT pre-turbo and it works well enough for just about everyone.

Is it perfect? No, but many people are over-emphasizing the importance of this. Unless you're competing in an EXTREMELY tight class of cars somewhere where every 1/8th HP on your bleeding edge engine tune is crucial, it doesn't apply to you.

your point is well taken ... do you have a link handy to a thread that discusses where we're at in more detail? I am taking materials engineering in school right now so i could try to investigate the sensor responses/calibration of various thermistors if needed. It would be really cool if you could use the IAT sensor to account for the evaporative cooling of a methanol/water mix for the people that run that setup.

John

Easiest way is to search for: hydra IAT

DarthChicken did a lot of poking around at it and I think n2xlr8n did also, both of them sold their Subarus though.

My MAF just hangs in the fender well by a zip tie for air temps.

Most of the time hanging the sensor in the engine bay will work. The main thing is how the sensor is mapped in the ecu. The main function for most is to alter timing and or fuel when in traffic or during heat soak. In that case this location works. It does not work going down the road in most cases and this is the reason that I trim those maps with this in mind.

Clark

Most of the time hanging the sensor in the engine bay will work. The main thing is how the sensor is mapped in the ecu. The main function for most is to alter timing and or fuel when in traffic or during heat soak. In that case this location works. It does not work going down the road in most cases and this is the reason that I trim those maps with this in mind.

Clark

So for those of us with MAF's acting as IATs post-turbo (mine is about 6" before the throttle body), what is the best procedure for calibrating that table correctly?

This is how mine is installed since I run Blow through. To tune the IAT sensor with the sensor in the charge pipe is simple. You are going to tune the maps as if the air you are sensing is going into the engine :) Most of the time this will be less timing at high intake temps (as intercooler or preturbo air gets hotter)rise.

Clark

This is how mine is installed since I run Blow through. To tune the IAT sensor with the sensor in the charge pipe is simple. You are going to tune the maps as if the air you are sensing is going into the engine :) Most of the time this will be less timing at high intake temps (as intercooler or preturbo air gets hotter)rise.

Clark

You mean it would pull less timing right? Since, if the map is set up to expect a temperature gain, but it doesn't actually since it is actually being read right before it passes the TB.

I guess what I am saying is that the compensation overall should be much lower because it is getting an actual reading right before combustion.

I would not know the value to use until I logged and tuned that particular car. There would be no way to guess how much timing removal would be correct for power and safety until it is tuned first hand.

Clark

I would not know the value to use until I logged and tuned that particular car. There would be no way to guess how much timing removal would be correct for power and safety until it is tuned first hand.

Clark

Well, looks like you are going to get to work on it in April when you come to Texas, woohoo.

Cool. Cant wait man. I should be able to get it tuned out.

Clark