Engine/Transmission (1998.5 - 2002) IAT sensor (cleaned )

[Cobra]

IAT

Alan Reagan

I have been reading all the threads on this issue. I am really impressed with your fuel milege. 21 mpg with a 4. 10 rear. I only get 17. 6 mpg and I have 3. 54 gears. I thought that was pretty good milege for a big heavy truck and I wasn't too concerned. Now after reading these threads, I think I will check out my IAT.

 

[fmj]

After reading this thread I went out to look. I've located the sensor but cannot get a 22mm or 13/16 socket on it. It looks like its over an inch?? I have an '01. Are these things different sizes? I need to know as I'll have to go out and buy a deep socket to fit.

 

[JR2]

FMJ - I have a 2001 also and I know the sensor is a 13/16 (sparkplug) socket. The one you are trying to take out is probably the MAP, it is 1 1/4 inch.

The IAT is back further and up a little. It is a lot smaller plug and sensor. It is darn near impossible to get out, I have to get up on the engine and bend over and and really work to see it.



JR2

 

[Archive]

OK, you guys have convinced me! I will pull mine out in the morning and check it.

 

[Evan A. Beck]

Perhaps exhaust brakes are part of the blame for dirty IAT?



Take the valve overlap into account, and it all makes sense. When there's 50+ psi of exhaust backpressure, wouldn't it be putting an increased amount of exhaust back into the intake side? I have noticed an increased amount of soot in the intake of trucks with e-brakes, as compared to those without. Looks like this IAT thing is going to become a twice-a-year checkout thing.



Will be checking mine tomorrow... I'll post results.

 

[TXRam]

I'm going to get a new one this week myself - I would love to see better mileage and lower EGT's by spending $18. BTW, mine is like alot of others have mentioned here - over 500F in drive sitting still, takes forever to get below 300F in Park with A/C off, mileage is not great but not horrible (16MPG with 4X4, auto, 4. 10), etc. If it doesn't help mine, I'll send it to someone else.



As far as the soot/dirt/etc. build-up on the sensor, it has to comes from some exhaust getting into the intake manifold, right??? I, like S Campbell, can't think of any other explanation.



Marco, Alan - Sorry for butting into you guys conversation.

 

[Evan A. Beck]

Forgot to add something...



When I was in Vegas about a year ago, I asked Lawrence at DD about a friend's (MikeR) lopey idle and heavy smoke. His first reply was to clean the IAT sensor, and replace it if necessary.



I just remembered that, thought I would add it to the conversation...

 

[bow hunter]

I think I will change out the IAT to see if my trucks exhaust cleans up (nox) the truck since new has always burned the eyes. I think the sensors in Denver are gold plated called a couple of dealers and they said $46. 00 cummins went up to $35. 00 ten dollar increase. .

 

[Alan Reagan]

Good point, Evan. I don't have a brake on yet, but was trying to figure how the really sooted ones got so dirty. Mine was not that dirty. If you you back to Marco's and my initial posts on this, my sensor was reading the wrong resistance. Therefore it was allowing more fuel to be added when it wasn't needed. Changed the sensor and I'm seeing less smoke.



Cobra, thanks for the compliment(?) on the mpg. I'm very happy with it. That's running a paper filter just to let you know. John Ponder has the same truck as I do but his is 4wd. He got 26 mpg on a constant throttle experiment he did from Atlanta to Louisianna.



My truck absolutely gets the best mileage running about 60-65 in long rolling hills. So that's what I run on the two lanes. When I run 70/75 on the Interstate I'll drop to 20 mpg. That's when I think it would be nice to have the 3. 54. Most of my mileage is on the two lanes so I'll stay with what I have.

 

[Marco]

Thinking loud here,

I F the soot comes from exhaust gasses that can enter the intake due to the valve over lap and backpressure on the exhaust side,

well then it's clear why the IAT's are so often shoot.



The exhaust gasses are way too hot for the sensor! Maybe not the first time it's heated brutally, sencond time for sure it's all gone.



Thought's?

Marco.

 

[Steve Campbell]

Marco, Cummins had something in mind when they installed the IAT sensor where they did??? I think your previous idea about moving the sensor further up the intake stream has some merit. Perhaps the intake "horn" would be as far as one would want to go to keep the temp differential close. The horn should not see much if any soot. If cool temps make the ECM think less fuel, then moving the IAT in front of the grid heater should give one a cleaner/leaner idle.

 

[Marco]

Then lower the temperature, then MORE fuel... .

Marco

 

[Alan Reagan]

Marco, Are your eyes darting? Are you beginning to laugh nervously about the possibilities here? Off to the laboratory... ... .

 

[Marco]

Hey Alan,

What do you think where I'm posting from???

I'm here working on the latest file for a certain guy in the States! LMAO



Marco

 

[DBuchheit]

I checked my local Cummins shop for an IAT sensor. They want $38 for it, which is considerably higher than the costs I've seen in this discussion. For those of you who have purchased these for the lower prices, where did you find them?



Thanks

 

[Alan Reagan]

Ramboat, got mine from the dealer. List $20. I said how about a discount. He knocked off 10%. $18.

 

[John Berger]

I need one

Hey Alan, can I get you to pick one up and send it to me. I checked both dealers in this area and prices were $25. 61 and $28. 60. Contact me by e-mail or private message if you can do this, give me your address (I think I have it, but I'm not sure) and I'll stroke you a check once I know the amount. TIA



John

 

[Alan Reagan]

I'm seeing the dealer today to pick one up. I'll be in touch.

 

[DBuchheit]

Originally posted by Alan Reagan

Ramboat, got mine from the dealer. List $20. I said how about a discount. He knocked off 10%. $18.

Alan:



I'm going to be driving by Warner Robins in about 2 weeks.



Is the dealer anywher near I75? If so, I may stop and pick up a new sensor.



Thanks

 

[John Berger]

Sensor looks pretty good

My IAT sensor looked pretty good, nothing like the pic JR2 posted. I cleaned it up and will see if I notice any difference. I don't expect to, but I plan on checking this thing at least once a year. I think I'll get a backup, just to have. Thanks to everybody for the tip.