iat sensor

[clipto]

I never used a iat sensor never seemed to mess with anything tune was always good. But my friend thinks its necassary. Is there any pros or cons im missing to have it for ecmlink?
I just wanna see to him if its necassary or not.

 

[WES_393]

Bottom of the page.
sd101 [ECMTuning - wiki]

As before, these logs were taken minutes apart from each other on the same car. The only difference between them is air temperature. In the first, air temperature averaged 65F while in the second, it was 133F.

However, unlike the idle logs, measured A/F ratio in these actually *did* change, suggesting that air temperature in these log actually did have an impact on airflow entering the engine.

 

[J_DiZ]

Are you running speed density? Or a maf setup? In the MAFs there is an intake temp circuit.

 

[clipto]

SD of course mafs are out dated with me.so ait is important to know or doesnt matter. Becuase tuning car weather always changes so cant really do anything bout it day to day.?

 

[slo2spool]

IAT is especially important with speed density, hence the word "density." The temperature of the air is a determining factor in how dense it is. The colder the air entering your engine is, the more dense it is which means you require more fuel in order to have the correct AFR...and the warmer the air is, the less dense it is meaning less fuel is required for the correct AFR.

 

[clipto]

Ok well I cant change the weather outside temps are ganna be whatever there ganna be, so im stick without it.

 

[slo2spool]

SD tuning is worthless without an IAT...And it has nothing to do with outside temps, it sees intake temps to help you figure out how efficient your turbo and intercooler are as well as determine exactly how much fuel is required to have the correct afr.

 

[WES_393]

Ok well I cant change the weather outside temps are ganna be whatever there ganna be, so im stick without it.

That's like saying roads are never straight so you'll just remove the steering wheel.

It's not hard to see how Density is an important part of measuring air, especially with a system called Speed Density...

 

[95DsManiac]

Like everyone mentioned the IAT sensor is vital. It measures the air coming into the car accurately and can make adjustments faster and more proper. SD is a master piece. I will never go without it now after switching it over to full sd. Check out the ecmtuning wiki there is a lot of useful information there that can help you out and better understand things.

Good luck,

Anthony B.

 

[clipto]

Very true but my tuner has tuned many many cars without iat and my car doesnt have a iat and everything is fine..

 

[YanDsm]

Why do you ask opinion if you have already decided that you won't put an IAT in your car???
It's really not expensive and you SHOULD have one installed for a good tune and a good running car.

 

[94allwheeldsm]

Why not just get an IAT sensor wire it up see how much better your car will run? Yeah Your setup works, but is it working as well as it should? You can buy a new GM IAT for less than $30.

 

[J_DiZ]

Epic facepalm is epic. SMH

 

[clipto]

It was a coversation with my friend is all just trying to find more info. As as much as iat maybe nice to have I have no need for it if you wanna come ride in my car and try to find something wrong with not having it your more then welcome. Otherwise I am good I was not looking for reason to get it just was fiding out why to get it and it seems rather not so important still to me. But feel free for everyone else to get it, just another annoying thing in the engine bay. Closed Thread.

 

[gofer]

Empirical Results - Temperature
The above discussion was all about the theory behind speed density operation based solely on air properties by themselves. But the reality is that air temperature is also affected by engine temperature. As air is entering the engine, it's heated by the temperature of the engine itself. This effect is more pronounced with slower moving air (idle/cruise) and gradually reduces in impact as airflow rate increases.

To account for this observed behavior, we have defined a coolant-to-air temperature weighting table in the direct access area of ECMLink. This table allows the user to define how much relative importance coolant temperature plays over air temperature (and vice-versa) based on airflow rate. The user can choose to ignore coolant temperature all together or ignore IAT all together or interpolate between the two.

Idle Logs
Because we know this concept may be not be mainstream, we offer the following datalogs that have *no* air temperature compensation. All the temperature compensation in both these logs is based on coolant temperature.

Hot idle - no IAT
Cool idle - no IAT

These were captured minutes apart from each other on the exact same car idling in the exact same spot in our parking lot. In one, air temperature varies from 172F to 130F while in the other it's only 70F the whole time.

In both cases, you see the resulting A/F ratio (measured by the LC1WB) is identical and combined fuel trim is fairly constant despite the fact that air temperature was NOT being factored in. In the hot log, you can even see where we disconnected the GMIAT sensor for a period of about 30 seconds, but absolutely NO change was observed in measured A/F ratio or idle quality. That was done to specifically illustrate that air temperature was not being factored into the airflow estimation.

If airflow temperature had been factored in, you would have seen a swing of (172 + 459) / (70 + 459) = 1.19 (19%) in mixture! Simply put, the temperature of the air had absolutely NO effect on airflow entering the engine at idle. We have collected other logs at cruise to illustrate a similar behavior.

Wide Open Throttle
However, at wide open throttle, the air temperature seen by the IAT sensor quickly takes over as the primary factor in determining air density. We have logs showing this effect as well with measured A/F ratio dipping to 8.3:1 with IAT at 133F compared to A/F ratio of 9.1:1 at 65F with boost around 20psi. These logs can be found below.

Cool pull - no IAT
Hot pull - no IAT

As before, these logs were taken minutes apart from each other on the same car. The only difference between them is air temperature. In the first, air temperature averaged 65F while in the second, it was 133F.

However, unlike the idle logs, measured A/F ratio in these actually *did* change, suggesting that air temperature in these log actually did have an impact on airflow entering the engine.

 

[slo2spool]

[QUO TE=clipto;153290416]I never used a iat sensor never seemed to mess with anything tune was always good. But my friend thinks its necassary. Is there any pros or cons im missing to have it for ecmlink?
I just wanna see to him if its necassary or not.[/QUOTE]

So you ask if an IAT is necessary or not and why, a bunch of people tell you that it is, with great explanations of why it is and you still say no. Why ask a question if you don't want to know the answer?

 

[95DsManiac]

I'm just going to say it! I guarantee your car will run better with it then without it. And why wouldn't you want to know you intake temps? Do you not know the cooler the air the more power is possible to be made? I'm really not understanding why you even posted? You ask about it, but then it sounds like you already know no matter what we say its going to be the same? Lets say your car is pulling timing and you have no idea why, well once your IATs get to a certain temp the ecu will pull timing, hint hint, meaning less power. So that's one reason to have it. It is a handy sensor and can be vital if used right. To be exact about pricing it is 16.99 at autozone right now. It's cheap and it works, been using it fine no problems. I'm come on man, what's the absolutely worst that can happen? Lose 16 bucks? Oh and by the way it doesn't really make a difference to the engine bay if done right. You can barely notice mine.

 

[ZenkaiRacerDsM]

While you're at it, why not remove the knock sensor too? Or the intercooler? Just more stupid stuff taking up room.

 

[tkelly27]

It was a coversation with my friend is all just trying to find more info. As as much as iat maybe nice to have I have no need for it if you wanna come ride in my car and try to find something wrong with not having it your more then welcome. Otherwise I am good I was not looking for reason to get it just was fiding out why to get it and it seems rather not so important still to me. But feel free for everyone else to get it, just another annoying thing in the engine bay. Closed Thread.

You can absolutely run without an IAT, it's not going to hurt anything as long as the tune is set up to be at a safe AFR when the temperature is cold. You go rich when it gets warm, but most people can't feel the difference of a few AFR.

I have had a few cars that came from shops around here (I'm from the Portland area too) that were setup with SD and did not have IATs on them. I can tell you that the tune was more consistent when we hooked them up.

If you enjoy your car you don't have to do anything you don't want to. What we're trying to tell you is that you can enjoy your car more if you make a simple modification.

 

[gofer]

Everyone saying the IAT is necessary aren't wrong, neither is everyone saying it's possible to run SD without it either. I'm not familiar with other tuning software but ECMLink has a nifty table in DA that allows SD users to run with no IAT sensor and still have a very accurate tune.

It's the tab labeled SDTempWeighting. Basically the columns in the table are based off of airflow readings (Hz) and range from 0 to 6400Hz, if there's a "0" in the column then the ECU uses coolant temps to determine air density so a IAT sensor isn't necessary.