Engine/Transmission (1998.5 - 2002) Iat = Mpg ???

[CFAR]

Before cleaning, after about 30k miles with a jake brake, used everyday, for everyday driving. I was expecting a dry powdery exhaust type of coating, but this was a wet dieselly (does dieselly have 2 L's) coating.



#ad






Clean, Clean, Clean at last.

#ad




I need to do the MAP sensor if this is any indication, Does anyone remember the socket size?



I have noticed a decrease in MPG's over the last year or so, not real noticeable at first, only if you look back over "THE BOOK". Usually I would get over 20mpg but that now hovers between 18. 5-19. 5mpg's. So time will tell if the cleaning helps. I have a 500 or so round trip this Thanksgiving so I will let everyone know.

 

[Rebel_Horseman]

I need to clean my sensors as well. I tried to get to the IAT sensor (isn't that the one on the driver's side of the block towards the rear of the engine?) but I couldn't because the socket wouldn't fit. It seemed the clearances between the sensor and the block would not accomodate the thickness of the socket. I'm going to try to use some of my other tools to get the thing out.



Reb [><]

 

[ProspectorTim]

CFAR, your signature block is too long, so I don't know ALL the details about your truck - but if you are running an oiled foam or oiled gause air filter (Amsoil, K&N, etc) then that is most likely the reason your IAT looks wet & oily.



Clean the IAT occassionaly; it is a small price to pay for superior airflow and filtration.



Rebel_Horseman, yeah that's it. Can't see it and work on it at the same time, and a bugger to get at; but worth the effort.



Somewhere on the internet, there is a diagram of all the sensors on the ISB engine, and another article about cleaning the IAT that has photos. I'm still looking for both.



edit: I found the IAT Cleaning article. Note that exhaust brakes also take the blame! Makes sense to me.

 

[Whitmore]

My IAT looks just like that every 10k when I clean it , I also check the MAP and it is always clean???, After the cleaning I always notice alot smother idle and about 1 on my mpg, I have been considering buying another IAT and installing it into my airhorn as close to the motor as possiblee to maintain some heat in the winter, I have read here of some putting the IAT into the airbox and extending the wires but I dont think that would work so good in Wyo.



Cheers, Kevin

 

[DDT]

I just replaced both sensers on my truck. I used a 1/2" drive 1 1/4" deepwell socket for the map. For the IAT I use a 3/8 drive 13/16 spark plug socket.

 

[Diesel Gunner]

You know, you guys really bug the snot out of me with this AIT cleaning. I have done it a couple of times. The sensor looks just like your photos, I clean it, high hopes and no change in fuel mileage.



I am expecting to see an increase in fuel mileage now, though. For about the last 6weeks I have been noticing the smell of raw fuel once in a while. I would look, but was unable to find any leaks. When I got home from work Tuesday I noticed a stain on the driveway about 3-4" in diameter. This time I bumped the starter and inspected real serious like. Great! It's that damn lift pump! It was leaking fuel from the bottom around the electrical connector. I am now on my third lift pump in 45K.



Yea, I will pobably continue to clean my AIT.

 

[dresslered]

I actually cleaned my IAT at about 45,000 miles and noticed some oily residue from the exhaust brake which originally had me concerned. I took resistance measurements before and after and noticed absolutely NO difference. No change in mileage was noticed either. I think that for the most part of it, it is a waste of time.

 

[BLACKRAM]

I asked Cummins Northwest about this very subject. They said cleaning it would do absolutely nothing. They further stated I risked damaging the Iat, as it is very "fragile" and would get worse mileage.



I don't know if they are right, but I value their opinion.

 

[Sticks]

Well here is the next mystery question(s).



Do you want to be reading higher or lower temps than actual?



I can almost answer that one myself. Higher than actual would be less fuel injected = better mileage, lower power. Lower than actual would be more power and smoke at times, and worse mileage.



Where else could you put it - IAT - other than the air horn?



For those of us that are installing the boost cooler injection, I would think that subjecting the IAT to blasts of very cool humid air (if mounted in the intake horn) would be unhealthy for it.

 

[pwr2tow]

Cleaning the IAT sensor did little for fuel mileage while driveing empty, but towing my mileage went from 8. 5 MPG to 10. 8 MPG.



I know 10. 8 MPG is not great but it sure beats 8. 5, I tow between GCW of 20,000 LB's and 22,700 lb's.



Ron

 

[ProspectorTim]

My mileage varies so much, depending on what mountain range I'm hitting, which trailer I'm pulling, or which way the wind is blowing - that I don't even bother trying to figure it out.



But when my oil analysis came back with "excessive soot" noted, I did a search on the forums and found that article about cleaning the IAT. After cleaning it, I took it for a test drive and after about a mile or so, it looked like the smoke was LOT less than before. This year's emission test showed the lowest opacity of any of my previous tests, and this is WITH the RV275 injectors.



Oh yeah. . the Cummins folks will also tell you NOT to use an oiled foam or oiled gause air filter, because the oil can contaminate sensors. Thanks, but I think I'll stick with my Amsoil air filter and clean the IAT every now and then - or replace it if needed.

 

[CFAR]

Filled up this morning 20. 2mpg, with the box turned off,(no pump wire)



I noticed the III's smoke more with the box off, but then I usually drive with the box on 1x1. (ez jumper1)



I will now turn on the box to 1x1 and see what the mpg's are. I haven't seen over 20 in about 6 months.

 

[HeavyHauler]

I cleaned my IAT several thousand miles ago and it did nothing. I can also understand why Cummins NW said it wasn't a good idea - I was afraid I was going to break the thing just trying to get it back in. It's not in a very good place and you pretty much have to guess as to where it goes.



Anyway, probably a waste of time like the others said. Mine really wasn't even that dirty with over 60,000 miles on it. I know that's the first time it had been cleaned.