IAT placement

For discussing how to choose sensors and create a wiring harness for all Bowling and Grippo versions of the MegaSquirt® EFI controller.
Forum rules
Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.

If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0).

If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days

The full forum rules are here: Forum Rules, be sure to read them all regularly.
Post Reply
commi
MegaSquirt Newbie
Posts: 1
Joined: Fri Jun 13, 2008 11:54 pm

IAT placement

Post by commi »

So i installed my GM type IAT sensor in the wrong spot by mistake/lack of knowlege - it is right after the intercooler and some distance before throttle body, where it sits now it doesn't take into the account the part of the intake piping that goes right over the valvle cover/part of the exhaust manifold so the air temps actually going into the manifold are a bit hotter than IAT reads....not sure how much difference it may be.

As far as I understand that sensor needs to be moved behind the throttle body and into the plenum or somewhere around there? It would be a major pain in the behind but if it needs to be done, it will be done.

And a little harder question - With how it is set up now, reading colder intake temps, how will this fool the ecu and what would be the end result. How does it affect the fueling and/or timing. Would I have to re-tune when i move it? And would it be a bad idea to tune under high boost with it where it is right now (18PSI)

Im on MS2 - latest version

thanks in advance
41Willys
MegaSquirt Newbie
Posts: 12
Joined: Mon Jul 20, 2015 4:33 pm

Re: IAT placement

Post by 41Willys »

I learned a similar lesson recently. I put the sensor below the blower, thinking that it was where the higher temperature air is, and that's what's going into the engine. Problem is, I'm injecting ABOVE the blower, and it was just messing things up for tuning. It would also heatsoak under there and become useless. I wouldn't tune until it gets moved. It'll just frustrate you. The higher the air temps, the less fuel the MS thinks the engine needs, because hotter air is less dense and needs less fuel to meet the target AFR. For me, it was just leaning things up too much. Also, putting the sensor "after" the throttle body, means that the incoming air may actually get cooler, because of the formula PV=nRT. Look at a throttle body or carb on a hot humid day. The incoming air will cool down going through the throttle body, and cool the throttle body and cause it to dew up and sweat. You'll be much happier with the IAT after the throttle plates.

Dan
Post Reply