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Old 06-14-2010, 03:36 PM   #1
Eatoniashoprat
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Default EJ20g PFC & IAT Sensor

Hi everyone, In datalogit there are parameters you can adjust to pull timing based on IAT, it also logs IAT. Problem is the engine never had an IAT sensor so the feature is useless.

I've been using a GM IAT sensor wired in to the black box to datalog intake temps after the intercooler and I'm wondering if anyone knows if I can wire it in to the ECU somewhere to actually utilize the IAT settings.

A better intercooler is in my future but for now I see some temp spikes up to 70F in long pulls (at 14 psi). Is there a pin on the ECU that will take this 0-5V IAT sensor input?

Its ok if the scaling is off because the in datalogit you adjust the temp settings and use a conversion table to convert from the value the computer is reading and actual temperature.

Mike
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Old 06-14-2010, 03:47 PM   #2
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Uhh we do have an IAT sensor its integrated into our MAF's.
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Old 06-14-2010, 04:13 PM   #3
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Oh yah . hmmm. I figured the ecu just took the MAF reading before the engine started and used that as its ambient temp reference during that run period. But when you said that I remembered the second element in the MAF.

I wonder why datalogit isn't picking it up then. Have to check the wiring maybe I'm missing a wire coming from the MAF?

Does anyone else's datalogit pick up an IAT value?

Mike
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Old 06-16-2010, 10:04 AM   #4
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The PowerFC is a JDM ECU, and the JDM models have a seperate intake temperature sensor, besides the one integrated in the MAF sensor.
The wiring probably is not there, but the ECU will utilise a sensor.The stock sensor on the JDM cars is placed in the intake snorkus.
Do not use the MAF sensor temp wire, as that is useless in a turbocharged configuration IMHO
The MAF measures temperature before the turbo and IC combination, so gives a reading nowhere near the actual temperature going into the engine.Most speed density ECU's measure intake temperature right in front of the throttle body, they do that for a reason, namely to get actual useable results.

To get the temperature reading/correction working:
The GM sensor (which i am not familiar with)most likely has 2 wires coming out of it, you ground one @ the ECU, and insert the second wire into the ECU at a specific pin.I have a working temp sensor/working retard on my own car, so it can be done
You will need the JDM ecu pinout of the corresponding year that your PowerFC is, and then locate the AIT pin in the pinout.That position you insert the 2nd wire coming from the GM sensor, and then it should work.
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Old 06-16-2010, 02:47 PM   #5
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^ I have a jdm imported GC8 and i do not have another IAT sensor in any part of my intake snorkus ... never heard of this before.
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Old 06-16-2010, 03:05 PM   #6
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OP...are you using a TMIC or FMIC???...if your using a front then you can move the maf to the IC piping making it a blowthrough...if your using a TMIC...well I have no idea but good luck
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Old 06-16-2010, 04:26 PM   #7
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@ Drew, maybe I am using the wrong word (snorkus), but it is inside the plastic piece which funnels air from above the headlight to the airfilter.

Quote:
STi V3/4 pinouts, there appear to be 2 conflicting sets but the last of the 4 pages shows B135-pin 1 is the IAT input.
From Northursalia's site

I know I have a shop manual page scanned somewhere, which shows the sensor to be there.
Also the pre-97 (So V1 and V2 STI0 do not have the sensor.

Last edited by Dutch Scooby lover; 06-16-2010 at 04:43 PM.
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Old 06-16-2010, 04:40 PM   #8
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^ Are you possibly talking about the temperature sensor that sits in front that is for the Auto climate control ?
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Old 06-16-2010, 04:57 PM   #9
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Nope, there is a dedicated Air intake temperature sensor on the v3 to v6 JDM STI
My FAST parts program is not working at the moment, as I am on a Windows 7 Pc or I culd show you the part number and a scan.
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Old 06-16-2010, 05:38 PM   #10
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interesting
i have it listed in my notes as
Connector Pin Function Color
B135 1 Oil pressure P/S or Air temp? White
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Old 06-16-2010, 06:34 PM   #11
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Found a Subaru Fast part number
22634 is the sensor, there is also a grommet listed.

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Old 06-16-2010, 07:07 PM   #12
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Aw ya your right i found it in fast aswell, the complete part # is 22634-KA071 not much talk about it though on google i don't think they used it very long.
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Old 06-17-2010, 12:33 PM   #13
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hmm so its an ambient temp sensor .. i wonder what its range is and if it would be good for a post IC temp or how pressure would affect it ...
would be a great point for the dataloger

not terribly expensive $21.64

a google search revealed it as used in the forester 97-02 .. which might make more sense
and a pict


in hind site a plastic sensor in hot air with nothing filtering it out befor the throttle body is not such a good idea
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Old 06-17-2010, 04:26 PM   #14
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The first thing you have to realize is that the PFC is hard coded to expect a certain resistance sweep from the temperature sensors (air and water temp). You can't change the calibration without doing something on the hardware level. So that means the GM Sensor is out, unless you just want to log voltages with a Datalogit.

There is a chance that the EJ20G air temp correction may actually be designed for the Apex'i IAT sensor, which is a rebadged Mazda/Denso part (same as the OEM 92-2002 Rx-7 sensor). The Apex'i part number is N3A11845 , which is a Mazda OEM part number. N3A1 is a '92 FD3S Rx-7 chassis code prefix used in part numbers. This Apex'i/Denso/Mazda IAT sensor is the part included with Power FC D-Jetro kits (mostly for Nissan RB and SR engines) to convert to speed density.

Here is the Apex'i/Denso/Mazda sensor:



It uses a Tyco/AMP Econoseal II connector (see www.bmotorsports.com) . It is an insulated sensor with a metal piece surrounded by plastic. The only other sensor known to match its resistance sweep is a Triumph motorcycle sensor. That sensor has an exposed element like the GM IAT except that its resistance sweep matches that of the Apex'i/Mazda/Denso unit. The connector is a standard Bosch EV1 fuel injector connector that you can get about anywhere. The open element sensors respond faster.

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Old 06-17-2010, 04:26 PM   #15
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On D Jetro/Speed density conversions for L Jetro models (like Nissan SR20) the IAT sensor is plugged into the side of the PFC and uses a long harness. On applications with an OEM IAT sensor the PFC just takes the signal from the factory wires (like Rx-7 13B-REW engine). I am unsure what sensors some of the other OEM D Jetro engines use, like the JDM JZA80 Supra 2JZ-GTE. I do know the Toyota MR2/Corolla 1ZZ IAT sensor is not the same as the Apex'i/Mazda/Densor unit shown above.

Every single Power FC map I have (the majority of which are from the sample maps that come with the Datalogit Software) has an IGN vs AirT correction table in Settings 4. It seems that, with perhaps an exception or two, all the engines that are L Jetro from the factory (such as the EJ20G) have the right column of this table zero'd out.


EJ20G


Nissan CA18 (180SX)

All the engines that are factory D Jetro (speed density) have this table populated with values for ignition timing retard.


Honda B18 engine (Integra)


Mazda 13B-REW engine (Rx-7)

Interestingly enough, the default map for the SR20 D Jetro PFC still has the IAT spark correction table empty (just like the regular L Jetro map), even though the D Jetro kit includes the aforementioned Apex'i/Mazda/Denso sensor.

If you want to do IAT correction, you first need to figure out what pins the PFC is checking for the signal. It could be coming from some factory pins or it may expect it from two of the pins on the side of the PFC.
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Old 06-17-2010, 06:13 PM   #16
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The V3/V4 STI PowerFC uses the factory IAT sensor pin at the ECU.
I know this, because that is how I got mine working.
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Old 08-30-2010, 12:10 AM   #17
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Sorry I'm a little late getting back to this thread, last I checked it hadn't gotten all these responses. Thanks for all the great info.


Engine: The engine is a 1989 JGM GT legacy wagon EJ20g, and there was no seperate IAT sensor.
PFC: I bought the PFC off rob, not sure what year its for.

I'm just getting to fixing this now, as the temperature is starting to drop here and it seems the ecu is not compensating for temp changes in the tune. I tuned it at about 35C and now its around 10-20oC and I've been adjusting fueling to compensate. I'm using a GM IAT post IC right now, if I can get this figured out I'll put the new IAT in the same location and then I can compare readings to make sure its scaled properly.

arghx7 --> does the denso sensor respond fast enough to use as a safequard to pull timing?

Which Pin? --> The wiring diagram I have does not show a Plug B135, the ecu plugs on mine are:
B95 - 12 pin
B43 - 22 pin
B96 - 16 pin
B44 - 26 pin

The only wire that is close to that description based on Jaxx comment is on B44, pin 16 goes to P/S oil pressure switch and its Purple('P'? pink?). I'll check out the ECU tomorrow see if its there.

DutchSL --> did you use the factory subaru sensor? How fast does it respond/have you logged with it? Did you put it in pre or post turbo? I'm thinking the same as Jaxx that I'd be wary putting that plastic sensor post intercooler.

Thanks everyone
Mike

Last edited by Eatoniashoprat; 08-31-2010 at 11:14 AM.
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Old 08-30-2010, 11:16 AM   #18
Eatoniashoprat
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For posterity I just called a mazda and a triumph dealer and found IAT part numbers:

Triumph - T1290088 $60CAD ships from UK.

No guarantee this is the right one, just the only one he could find.


Can also find it at fighters-garage with the pigtail for a good price

Denso/Mazda - I just called and asked for the number that arghx7 listed above and its close but its missing an '8'. The P/N he told me was: N3A118845

Last edited by Eatoniashoprat; 08-31-2010 at 11:14 AM.
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Old 08-31-2010, 11:04 AM   #19
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I had a look at my ecu plugs and on the 26 pin plug, pin #16 there is no wire. So if I'm looking at the right one I'll pin that slot and try it I guess
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Old 09-17-2010, 10:17 AM   #20
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Hi guys, so I've dug into this further and am now really stumped.

I've got the 4 yellow plug ej20g harness and I've hooked a resistor to ground (in the same resistance range as the IAT sensor should be) and then to the Power steering Pressure switch pin and I can't get the the commander to read anything.

I went a step further and tried to hook it to every pin on the ecu that said No Connection and still nothing.

I don't know wtf is going on here. Two scenarios I can think of:

My PFC is from a year of car that had a seperate IAT and I'm just not hooking to the right pin.

OR

My PFC is correct for my harness and for some reason isn't seeing the temp from the MAF. I've tried 3 different MAFs and get the same thing. The commander just shows '-----' for IAT reading.

In the MAF harness there is 12V, signal, ecu ground, and body ground, how does the ecu read temp from that if there isn't a seperate wire for it? Or does the temp compensation happen right in the MAF sensor?

Any help would be great, I'm struggling .

Thanks

Mike
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Old 11-21-2012, 07:38 AM   #21
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Default IAT input

Quote:
Originally Posted by Eatoniashoprat View Post
Hi guys, so I've dug into this further and am now really stumped.

I've got the 4 yellow plug ej20g harness and I've hooked a resistor to ground (in the same resistance range as the IAT sensor should be) and then to the Power steering Pressure switch pin and I can't get the the commander to read anything.

I went a step further and tried to hook it to every pin on the ecu that said No Connection and still nothing.

I don't know wtf is going on here. Two scenarios I can think of:

My PFC is from a year of car that had a seperate IAT and I'm just not hooking to the right pin.

OR

My PFC is correct for my harness and for some reason isn't seeing the temp from the MAF. I've tried 3 different MAFs and get the same thing. The commander just shows '-----' for IAT reading.

In the MAF harness there is 12V, signal, ecu ground, and body ground, how does the ecu read temp from that if there isn't a seperate wire for it? Or does the temp compensation happen right in the MAF sensor?

Any help would be great, I'm struggling .

Thanks

Mike

Sorry to drag up an old thread but did you ever figure this out?

I want to install a IAT sensor in my JDM version 4 Impreza STI Type R so i can data log intake temps via datalogit & laptop.

Be very grateful for any info as might save me a ton of time

Chris.
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Old 11-21-2012, 08:03 AM   #22
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Maybe he hasn't but I have.
The STI ECU measures airtemperature in 2 different places.

-Inside the MAF housing itself.This is done at the MAF and the value is corrected in the outgoing signal.There is no seperate MAF air temp signal to the ECU, as the MAF does it's own correctioon, and just alters the MAF v signal going to the ECU.

-Near the intake area.
There is a seperate sender there, on the STI models.
This sensor can be bought through a dealership, or one can use a standard intake temperature sensor that's used by most speed density driven ECU's.
(Autronic, Syvecs or AEM for example.)
This is a 2 pin sensor.One pin goes to a good ground (I used a 2 wire shielded cable, and used the ECU ground, as I already had to run a wire to the ECU for the signal), the other goes to the ECU, on the unused IAT/PS pin.

It could be the sender is off (gives a higher or lower temperature then the actual temeprature) but as the PowerFC's temperature values can be changed this is not a big problem.
You just have to find out how much your sender over/underreads, and add/subtract that number to values in the FC datalogit software.
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