GM IAT sensor question.

[C.Plavan]

I have seen on some of the Subi boards that people are using the GM IAT for Speed Density. Can I do the same without running Speed Density?

I plumbed a GM IAT into my AWIC. I was just going to run it straight to my datalogger/display. Then I thought..... Can I run the wires to the MAF like they do? Basically disabling the stock IAT (which is in a very inaccurate position). I'm sure I would have to change the values of the IAT in the Cobb Accessport software.

Thoughts? Or am I opening another can of worms?

[metalmaker12]

It can be done, but done completely correctly seems to be the issue. My very experienced tuner won't touch a maff setup. He said it will work with some tables but not others and will cause more problems than bennifits. I have voted to stay away from it. If you lower the maff tables enough and have a post IC iat to a gauge with an efficient IC system than the relocation and all the tuning that goes with it is not needed.

Ps do you have a bleed screw on your awic

[JeromeS13]

With the factory ECU as is with a MAF based tune, the ECU "knows" that the IAT sensor is pre-turbo. There's no real benefit (probably more harm than good) if you wire in your GM IAT sensor, with a MAF based tune. Why don't you want to switch to SD?

[C.Plavan]

With the factory ECU as is with a MAF based tune, the ECU "knows" that the IAT sensor is pre-turbo. There's no real benefit (probably more harm than good) if you wire in your GM IAT sensor, with a MAF based tune. Why don't you want to switch to SD?

I may later with a bigger turbo. I have the stock TD04 with Stage 2 map.

I just ran the IAT to the datalogger. It's pretty cool to see it work in real time on the Traqdash.
http://i.imgur.com/CsVN24al.jpg

[sponaugle]

I have seen on some of the Subi boards that people are using the GM IAT for Speed Density. Can I do the same without running Speed Density?

I plumbed a GM IAT into my AWIC. I was just going to run it straight to my datalogger/display. Then I thought..... Can I run the wires to the MAF like they do? Basically disabling the stock IAT (which is in a very inaccurate position). I'm sure I would have to change the values of the IAT in the Cobb Accessport software.

Thoughts? Or am I opening another can of worms?

While you certainly can replace the factory IAT sensor with a GM IAT one, if you are leaving said new IAT in the same location there really isn't any gain. The factory IAT sensor that is included inside the MAF sensor housing is an exposed element sensor similar to the one in the GM IAT sensor.

If you use an IAT sensor that is post turbo and post intercooler (in your case in the AWIC), you will have to make adjustments to a number of tables in the ECU. As MM said above the factory tables are calibrated for a pre turbo IAT. This is not that hard to do, but some tuners are hesitant to do it. That might be in part just due to lack of experience with this particular setup. I have done it many times, and if done correctly it provides a more accurate and useful control system. This is especially true in a car where the intercooler setup is questionable... By having a post IC IAT you can calibrate the car to have significant failsafes at very high IATs. That would have probably saved the factory five race car that was running 240 degree F POST intercooler temps.


With the factory ECU as is with a MAF based tune, the ECU "knows" that the IAT sensor is pre-turbo. There's no real benefit (probably more harm than good) if you wire in your GM IAT sensor, with a MAF based tune. Why don't you want to switch to SD?

Agreed on this.. why not just run speed density, especially if you have an accessport. With the realtime tuning it is easy to calibrate. You can calibrate a MAF tune to use a post IC IAT, but if you are doing a post IC IAT you should consider just doing a speed density tune.

MAF tunes are a bit easier to get right, but a good speed density tune can be more responsive and have better safety margins, especially if you are going with a larger turbo.

Jeff

[sponaugle]

I may later with a bigger turbo. I have the stock TD04 with Stage 2 map.
I just ran the IAT to the datalogger. It's pretty cool to see it work in real time on the Traqdash.

Ah yes... if you are on the stock turbo setup with a well calibrated MAF setup.. you are in the right track.
It is cool to see the IATs change in real time, especially post IC. If you put on pre IC you will probably be surprised how hot it is.

Jeff

[Bob_n_Cincy]

Ah yes... if you are on the stock turbo setup with a well calibrated MAF setup.. you are in the right track.
It is cool to see the IATs change in real time, especially post IC. If you put on pre IC you will probably be surprised how hot it is.
Jeff

Jeff
I am running 04fxt w/stock td04 turbo, stock TMIC and stock tune. I'm am changing to a big AWIC. Do I need any tuning updates?
Bob

[sponaugle]

http://i.imgur.com/CsVN24al.jpg


That looks fantastic.

[metalmaker12]

If I had the experience with the location changing of the iat in a maf based setup I would try it, but I don't feel comfortable enough. My good friend and very experienced subaru tuner has tuned thousands of cars and has done it, but warned me it had more cons than pros in terms of reliability of the whole system. I have tried to get him to try it, but he just won't do it any more and even stated that the maf setup is much more reliable than the speed density in my jdm ecu. I have known him for awhile and trust his judgement since he tunes like 10 plus cars a week. It can be done and will help you control the iat issue but might open up worms in other tables. Jeff knows his stuff and might be able to tune it right, but not every tuner will be willing to do so or feel the same. It's not a beginners try, and some seasoned tuners won't touch it either kind if thing.