What about relocating the IAT?

[Marco]

Gang,



Need your advices. The IAT sensor is located at the end of the head. The farest location form the intake.



Why?



Wouldn't that mean that it reads higher air temps than actually are present?



I'm lead to believe that in this location the IAT sensor isn't exposed to the "fresh" intake air.



What would happen if I relocate the sensor to let's say the intake elbov? Wouldn't that location for the sensor give a more "true" reading of the air temperature?



Also in that location the sensor shouldn't be prone to the grime JR2 has found.



I've never mentioned the fact that the IAT also fine tunes the timing. Wanted to keep things as simple as possible.

Then lower the temp then more advanced the timing, then higher the temp... .

Got it?



There is also a BUT! Would relocating the IAT kill MPG?



Shoot your thought's!

Thanks,

Marco.

 

[BLACKRAM]

Why doesn't somebody try it and post it?

 

[Cryppie]

Marco,



I agree that #@*&% thing is a bit difficult to get to waaay back there, and it's also in probably the hottest place on the engine (less the turbo). But, moving it to the intake elbow won't work in my opinion. That would put the sensor before the intake grid heaters, and give an inaccurate air temperature reading during cold months. Maybe if it was located in the intake manifold next to the grid heater. What do you think?

 

[Oasis-3]

Maybe a winter and summer location?

 

[SmokinJoe]

Originally posted by Marco

What would happen if I relocate the sensor to let's say the intake elbov? Wouldn't that location for the sensor give a more "true" reading of the air temperature?

I would install it into the air box, in a direct path of the air that feeds the turbo. If the air was clean that too would be a plus. I wonder if the ISB from Cummins has one and where they put it? Is it possible that where DC put the sensor is a bad place on a truck but an excellent place on a generator/backhoe?



Is the characteristics of the sensor such that moving air gives it a false reading?

 

[Ram4Sam]

Seeing Joe's post go me thinking My 99 PSD had a sensor in the airbox, on the dirty side of the air cleaner. If I remember right it was an air temp sensor.



Sam

 

[Marco]

All,



Cryppie, that's a very very good point! I didn't consider the Grid heather! DUH!



Oasis-3, yeah that could be an good idea. Something like having two sensors on the engine and simply moving the plug. Could be done!



Smokin Joe, Ram4Sam, I don't think the air box is a good location for the IAT. The turbo heats the air, the intercooler cools it , the ECM needs a accurate reading of the air temperature entering the engine. So I think the only possible location is somewhere on the intake after the intercooler.



Thanks for your help!

Marco.

 

[ACoyle]

Isn't there a plug where you get the boost that's closer to the front? Maybe swap the two.

 

[Oasis-3]

Intake Air Temp.

Just to be different I installed my boost gage on the intake elbo and put a temp. gage in the plug that every one is using for the boost install. I have had this in for about a week and a half now and the air temp I am seeing the most of is 110 F to 120 F after the truck sets for a short time, say to run into the store for something the temp goes up to about 140 F to 145 F then after running for a short time comes back down to 120 F range again. And if I get into the go peddle hard it will come down to 110 F again then go back up to around 120 F. The reason I have done this is to see how much the temp. goes up when running the AC but I have not run a long time with the AC on and off to get a good reading on this.



Hope this helps

Cliff

 

[MikeR]

Hey Marco,



I'm willing to try this for the mileage comparison,but won't be able to have a report until the end of next month (my next vacation).



One of the NW BOMBers has an extra elbow since he installed a Banks high ram,and if I sweet talk him enough,maybe he'll give it up for the experiment.



I wouldn't worry about the intake heaters. The only time they come on around here is during the winter time when the engine is very cold and the truck is sitting still. Once the truck moves faster than 30mph the heaters turn off.



I too have taken my IAT and MAP off and saw alot of oily crud building up on them.



-Mike

 

[ynot]

We talked about this last week on the "other site" and I decided to remove it all together and let just let it sit under the hood in ambient, and replace the grid heater for summer with an empty intake spacer. Marco's right. You won't get the timing retard accompanied with hi intake heat. The intake temp at 45psi is actually closer to 275 or 300 on a hard pull, also depending on ambient. The cooler gets heat soaked when the turbo is that far out of it's map range. I also heard it de-fuels quicker with hi intake temps. Lower or stock boost wouldn't have the much effect either way. Bypassiing the IATS will also make fuel mileage drop a bit, as you lose more ECM control... T

 

[TowPro]

Re: Re: What about relocating the IAT?

Problem is the intake temp incresses about 10 deg for every pound of boost.

Originally posted by Smokin Joe





I would install it into the air box, in a direct path of the air that feeds the turbo. If the air was clean that too would be a plus. I wonder if the ISB from Cummins has one and where they put it? Is it possible that where DC put the sensor is a bad place on a truck but an excellent place on a generator/backhoe?



Is the characteristics of the sensor such that moving air gives it a false reading?

 

[SmokinJoe]

Originally posted by Marco

Smokin Joe, Ram4Sam, I don't think the air box is a good location for the IAT. The turbo heats the air, the intercooler cools it , the ECM needs a accurate reading of the air temperature entering the engine. So I think the only possible location is somewhere on the intake after the intercooler.

What I suggested was PRE-Turbo. The air before the turbo and after the air cleaner. Basically in the airbox or that U shaped hose feeding the turbo.

 

[Marco]

Smokin Joe,

The IAT sensor needs a place after the intercooler as close as possible to the engine's intake. That's due to the fact that the turbos heats the air. The IAT sensor needs to give a reading as close as possible to the real air temp to work properly.



Marco

 

[Marco]

Did it

I did it this Morning. I've re located the IAT.



I've done a ten miles test trip. First impressions are, off boost smoke seems to be slightly less, but this could be due to the lower temps we're having here today. ( low 80's today, 90's in the previous days). EGT at idle seems to be about 50°F lower, EGT's under load... dunno yet will keep you posted.

Marco

 

[rono]

Marco, what did you plug the original hole with?



ron

 

[Marco]

He He, you'd like to know?!?

A magic, hard to find gizmo... .



My old IAT sensor! LOL





Marco

 

[Murle]

Funny!!! I was wondering what would happen if you spliced the wires and had 2 IAT plugged in??? Makes you wonder.

 

[JJMiller]

I understand why cummins placed the IAT sensor where they did--they want the IATS to give the ECM the temperature of the air just before it enters the cylinders. If you move it farther upstream, the IATS may show the ECM cooler temps, but it's not accurate for the purposes of basing fueling and timing.



If you place the IATS farther upstream, you gain the benefit of not having the ECM defuel and retard timing at very high IAT's, but as YNOT pointed out, you lose fuel mileage if you bypass the IATS completely.



I don't know the properties of the IATS, but it seems like you could design a circuit that would "clip" the IATS readings, much like the boost module does for the MAP sensor.



--J

 

[Blkdawdg]

How did you do that?

Hey Marco:



How did you get the sensor wire to reach all of the way to the intake elbow? I was going to try that but I don't ahve enough wire. Let me know so that we can have two independent tests going.