What about relocating the IAT?

[Marco]

JJ,

The really high intake temperatures are reached only at WOT.



The ECM does NOT use the IAT under WOT.



Placing the IAT upstream has nothing to do with HP gains in the upper range, but I think it will give a more reliable signal to the ECM in the low/mid range. I think the IAT sensor will see a slightly lower temp where I've located it now. Thus it should advance the timing a little. If I'm right here than the timing advance should give me some slight MPG gain. This should make up the mileage loss I get through the lower temp reading.

Confused? You might ask for what I have moved the IAT?



EGT's! Lower EGT's better mileage!

( Given that no other parameter has been changed on the engine)

My hope is that the new location for the IAT provides a more realistic reading of the air temperature to the ECM. This should allow the ECM better "fine tuning" for the fuel and timing.



Will it work? I don't know yet. It seems that the EGT's are somewhat lower, but it's possible that I see what I want to see. I'll report the MPG as soon as I'm able to provide hard numbers by miles driven divided gallons used.



Blkdawdg,

It would be GREAT to have someone perform an "independent test". Mostly because my truck is heavily modified. Dunno if my findings will work then on a stock( or near to) truck.



In fact there isn't enough wire. I've cut the plug and soldered about 10" of new wire to it. Finished the job with heat shrink and wire loom.

The PITA in this job is to solder then down there where the plug ones was. Took my almost half an hour to solder two wires.



All in all it took me about 1 hour to do the whole thing.



Marco

 

[Marco]

Update

Gang,



I thought I could have provided some hard mileage numbers with the relocated IAT.



This weekend I went to my boat, the trip takes me normaly about 75 minutes. This time the traffic was so heavy that it took me 2. 5 hours to get there.

The way home on Sunday was over 3 hours. Lot of stop and go traffic.



So I'm not able for now to provide hard numbers.

Sorry.



For now I can only confirm that the EGT's are about 50°F lower than before ( That's from idle to cruising). The EGT's cool down faster( a little) than before.

I get also a little less off boost smoke.



Marco

 

[GBenson]

These are for the gas motors, but could one of them be adapted to fit?



http://www.speedtweaks.net/IAT_Adjuster.htm

 

[Marco]

Hmmmm,

nice gizmo! A little pricey for a pot and a switch.

I can tell you that I've already done that test.

I've connected a pot instead of the IAT sensor to the ECM.

Seat of the pants meter sez, nothing, only more smoke when the temperature ( resistance ) is set lower than it actually is.



Their site also states that the IAT is used under WOT... .

That's NOT TRUE. Well at least for the Cummins. If I remember right, also the gas engine in my previous 5. 9L didn't use the IAT @ WOT.

Marco.

P. S. Telling the ECM the air is cooler is exactly what kills the mileage!

 

[Marco]

MPG update

Hi Gang,

This weekend I've been finally able to test the mileage.

Filled the tank, bingo! Plus 0. 5 MPG.

OK, I know, only one tank means nothing,or little at best. Getting a little lower EGT's, a little less smoke and a little better MPG seals the deal for me. The IAT will remain in his new location!



Very soon also my MAP sensor will find a new home. Less heat, less soot...

Marco