Engine/Transmission (1998.5 - 2002) IAT sensor

[moon]

There was a post a while back that said if one cleans the IAT sensor that the mileage goes up,aparently this sensor has something to do with the timing,someone on the subject wondered if one could put a resister on the wire to fool the computer to advance the timing resulting in better fuel mileage. I am surprised that no one has picked up on this to see if it is possable. It would have to be someone a whole lot smarter than me to maybe figure this out but i am sure there is one of you guys or (girls)out there with the smarts to experiment with this.

 

[Steve Campbell]

I am kind of thinking....

That it is one of those things, if working properly, that just does its job, and quite well, in its stock form IMO. Marco installed his in his air horn, which changed the operating characteristics a bit (richer fuel) but it does not get dirty now.



On the other hand, what you suggest has not been tried to my knowledge. Without a good test, we don't know that you may just be correct.

 

[HeberRam]

IAT sensor

Yelloweyes..... You are close. The IAT sensor if working properly reads the manifold temp and adjust the timming and fuel accordingly. If it senses the engine is cold, more fuel is applied. If the it senses the engine is hot less fuel. . The problem with the sensor, in its current location is its gets dirty real fast and with that said, will give false readings to the Ecm. It works on the electrical resistance system. . The more resistance, the more fuel, the less resistance, less fuel. . I have found, with those running big injectors, exhaust brakes the IAT gets dirty real fast..... Now I'm going to let everyone in on a little secret. When it is hot, like summer, if you want to say drag race, get good pick-up, have your'e truck run smooth, don't care about fuel mileage etc. , disconnect the plug to the IAT, insert a $. 17 45k ohmn resister from radio shack one end into each female plug end and notice the difference. The 45k ohmn resister is approx. telling the ECM the engine temp is around 25 degrees... Therefore, more fuel, more power etc. Get the picture???? So when you drag race, more fuel, more power. So now what I did, was since I didn't want to play with resistors, wanted all around performance etc. , and because the IAT is in a lousy place to keep clean, I simply unplugged the connector, spliced into the two wires on the connector, extended the line approx. 8', bought a brand new IAT sensor, removed the filter minder on the intake air box and pushed the IAT sensor into the rubber grummit (perfect fit) and you are done. Now what the IAT sensor is reading is the air temp (outside) comming into the turbo which should always be cooler then the engine manifold temperture unless you live in death valley. My truck runs better then ever, the IAT should always keep clean... . With this set-up you would probably see a drop of . 5 miles per gallon..... Big deal, performance gain and the way the engine runs far out ways the extra fuel... Try it and if you like what you find, send me $10. 00 .



Steve

 

[stownsend]

HeberRam,



Slight correction. In your thread, you said "buy a 45 amp resister". Do you mean 45 ohm? There may also be a current rating (amp), but to buy a resistor, you will need to know the resistance rating.



Just helpin.



Steve

 

[HeberRam]

Yup!!!!

Thanks, Steve..... You are right, got to be more careful with you tech guys!!!



The normal IAT Sensor resisent values:



30 degrees =40k ohms

32 " =30k to 36k ohms

76 " =13k ohms

77 " =9k to 11k ohms

81 " =6. 8k ohms

122 " =3k to 4k ohms

130 " =4k ohms

167 " =600 to 675 ohms





That's why I chose to use outside temperture as an average, because it will always be cooler then manifold temperture, therfore, more fueling.



Steve



Is everyone more confused???

 

[joel]

Geez - here's a thought.....

Since all the fueling boxes have to splice into the wires somewhere, why not make one that adjusts the resistance at the IAT and plug it directly into that connection. Just leave the regular IAT screwed into the manifold for system integrity - well, actually, connect that, too, so if you want a "stock" fueling schedule you can just bypass the box - and run a switch to the dash with several "power settings" that change the resistance fed to the computer to an appropriate level? Would something like that work?

 

[HeberRam]

Joel..... Good thought, however, the amount of fueling and timming changes by playing with the IAT sensor alone might get you 15 + HP. I know on gasers by relocating the IAT sensor or bypassing with a resister etc. has netted approx. 12HP on a dyno... . I have not done this on a dyno with my truck, but if someone would I bet it would be 15-20 HP on a stock truck and perhaps more on a bombed one...



That's one reason your truck seems to run better when the weather is cold is because the IAT is reading a cooler temp and increases fueling... . Cool air is more dense thus more fuel is required for proper burning... .



Why do you think I run NOS... ... Yea Baby, got to like the smoke... ...



Oo.





Steve





OH OH... . me thinks I just let out another Dyno trick?????

 

[RBSOB]

Great Info Guys

I will be trying this out very soon Thanks, Jim G.

 

[Ron Bissett]

Cooler air?

Will placement of AIT in manifold intake be cooler do to air passing through the intercooler or would the air at the filter be cooler ? Ron Bissett in LOUISVILLE KY

 

[Steve Campbell]

Under normal circumstances...

filter air would be cooler. There are exceptions... but rare!!

 

[MLee]

IAT

can i assume that the IAT is a 24 valve item, that has to do with the electronics of said trucks?

MLee

 

[HeberRam]

Mlee... yes. On the 12v there is a IAT and not sure how it works?? Someone has told me on those trucks , you simply disconnect it??? Maybe someone with a 12v has some experience and chime in ...





Steve