Engine/Transmission (1998.5 - 2002) Iat Bomb?????

[Adam]

Now don't everybody start yelling at me at once, I'm NOT electrically inclined, and this thought just came to me. Here goes...



Has anyone thought of replacing the IAT sensor with a resistor controlled by a rheostat? This way you could control what the engine sees as air temperature from inside the cab with the turn of a dial. Obvious uses include not letting the grids cycle when you turned the truck off 45min ago, or keeping the grids on longer for the initial start of the day. Might also be able to tweak fuel consumption or power, but again, I'm not an electrical engineer.



There's my idea. . now go ahead everyone... tell me why it won't work?



-Adam

 

[ACoyle]

I can't say that it won't work. Since I have an Espar, I frequently don't want the grids to work. I would be concerned that it would advers;y affect [erformance / milage and the ECM uses the info.

 

[dresslered]

If you don't want the heater grids to cycle why don't you just put a manual switch on the relays? As far as turning the IAT into a manually operated device, I really don't see how you would know where to adjust it to. I think for the most part, the effects would be so minimal that you would have to drive great distances and take mileage measurements to determine whether you have done anything worth while (and this would all be for a single temperature). Now perhaps if you wanted to purposely make the mixture rich or lean, you might be able to come up with fixed resistors which could be toggled in series and/or parallel with the IAT thermistor. I think that there are probably easier methods to try to accomplish what you are suggesting, but hey, give it a whirl and let us know how it works.

 

[DEZLPWR]

Yes, there are easier methods....

Just have Gordon @ Practical Solutions make you a harness to relocate it to your air filter... . IAT stays clean and adds a little more fuel to the engine because it is not picking up the engine heat.

That's what I did, and I am very happy. MPG, is down . 5mpg @ most. Engine seems to run smoother and maybe a little peppier. I have the PS Intake Heater System Saver installed so the relocated IAT doesn't make the grid heaters cycle continuously.



Thanks to Kent Earnest & Heberam for the idea! Oo. Oo.

 

[JR2]

I once read a post on here that claimed you could get 20 hp by fooling the IAT into thinking the engine was cold... . I have a new IAT and am looking for the connections to make the jumper... .

 

[Adam]

Just a vague concept for now...

I'm not really thinking of a way to bypass the computer solely to stop the grid heaters from cycling. What I was thinking of was a way to avoid dirty IAT sensors, and maybe a way to boost performance within the parameters of the current ECM. Some of the side effects would be manual control of the grid heaters, say for extreme cold starts when the regular 190 second cycle isn't enough. One sign of my electrical ignorance is the way I worded my original post. What I should have said was the ability to control the voltage by way of a rheostat, without even mentioning resistors. There would be no need for any resistors (I think?). If I remember correctly, some of the others have done tests on the output of the IAT and have a range of voltage readings that correspond with certain temperatures. If the rheostat was controlled to allow only the voltages normally seen by the IAT, no fault codes would be set, and you could manually control the sensed air temperature, and the corresponding fuel. Does this make sense, or should I just sit patiently in the corner waiting for the little men in white coats to politely ring my doorbell ?



-Adam

 

[rono]

Adam, I asked this question a long time ago and Marco answered back and said that it was not that simple and would not work the way I thought. He didn't explain why so I let it go, I figured he knew more about it than I did. Maybe he will jump in and tell us more.

Ron

 

[dresslered]

Adam-

The IAT is a thermistor. It is basically a variable resistor whose resistance changes with temperature. A resistance in parallel would reduce the overall resistance (act like the engine is running hotter) while a resistance in series (act like the engine is running cooler) with the IAT would increase the resistance. The only way to prevent the sensor from contamination would be to relocate it as Marco has done. Also, if you do not have an exhaust brake, this is not an issue. I have an exhuast brake and have found the sensor to be filthy, but after cleaning it up, there has been no noticeable affects (resistance was within tolerance).

 

[DEZLPWR]

TTT



We need some more input on this.....

 

[Behr]

Well... . seeing how we are on the topic of IAT.....



I was just wondering if the IAT also controls when the main radiator fan comes on. I have noticed at times when I first start my truck let it warm up for about 5 or 10 min... then drive off... I can hear the roar of the fan. Once the engines gets up to temp... . the fan stops...



Could this be IAT senor related... . ???

 

[Behr]

Well..... I just found one answer to one of my questions... .



Thought I would pass along this link regarding IAT's.....



Can never get too much info..... right??



http://www.smokindiesel.com/Technical.htm

 

[dresslered]

I was just wondering if the IAT also controls when the main radiator fan comes on.

No. The viscous fan drive is a mechanical device which engages via a bimetallic spring coil. It should not engage when cold.

 

[Steve Campbell]

Does anyone know .....

... . what size threads the IAT has? I am considering moving it to the air horn like Marco, but can't find a tap in my assortment that will fit it. Is it metric?

 

[Mundgyver]

If I may make a suggestion here, why not just buy another sensor and install it, in the intake horn. You now have two and would be able to switch back and forth between the two with out having to remove anything. Something else to think about here is that as the engine warms up, the fueling requirements will be different. The current location of the sensor allows it to see the engine as it comes into the operational temp band. As stated earlier, moving the sensor will yield . 5 mpg less, so you are putting a little more fuel to the engine. You would need a dyno to see what the gain if any would be. I would also think that you would see the additional fuel on the exhaust temp gage.

I too have thought about moving the sensor but have not done so. My plan is to add another one and switch between the two for testing purposes.

All sensor locations were picked for a certain reason by Cummins when they designed the engine. Our problem is that we do not have an understanding as to why the locations were picked as they were. Food for thought guys.

 

[HeberRam]

IAT Relocation

Guys... . I have been running my 2001 HO with a relocated IAT sensor to the air box for over a year now... Left the orginal in its place, purchased another, took out the useless filter minder, installed the new IAT sensor with a rubber grumit in the filter minder hole... Truck runs better then ever, no fouled IAT sensor, no drilling a "humongous" hole in the intake horn, and the IAT reads the ambient outside air temperture!!! Simply tap into the 2-wire leads that goes into the existing IAT run 2-lengths of #16 wire, to the new relocated IAT sensor and plug in. You can use the orginal plug connector by cutting it off or purchase a new lead wire connector at auto parts store. To make a more professional install, put the two #16 wires in wire lum... .



This is not to increase mileage, but to fool the ECM to increase fueling as in cool morning engine starts, however, you got that advantage all year round. More fuel, more power, better running at low boost levels, etc. etc. etc. etc.....



good luck!!!!



Steve



P. S. DEZLPWR. . Glad its working for you.

 

[HeberRam]

IAT Relocation

Guys... . I have been running my 2001 HO with a relocated IAT sensor to the air box for over a year now... Left the orginal in its place, purchased another, took out the useless filter minder, installed the new IAT sensor with a rubber grumit in the filter minder hole... Truck runs better then ever, no fouled IAT sensor, no drilling a "humongous" hole in the intake horn, and the IAT reads the ambient outside air temperture!!! Simply tap into the 2-wire leads that goes into the existing IAT run 2-lengths of #16 wire, to the new relocated IAT sensor and plug in. You can use the orginal plug connector by cutting it off or purchase a new lead wire connector at auto parts store. To make a more professional install, put the two #16 wires in wire lum... .



This is not to increase mileage, but to fool the ECM to increase fueling as in cool morning engine starts, however, you got that advantage all year round. More fuel, more power, better running at low boost levels, etc. etc. etc. etc.....



good luck!!!!



Steve

 

[MA-1]

I have done some experimentation regarding the IAT sensor with some interesting results. I left the original sensor in its stock location, and installed a new one in the end of my BHAF. I then fabricated a harness that utilized the stock connectors. The first time I tested the truck with the IAT in bombed position, I noticed that my boost jumped from 38 lbs to 42 lbs with no other changes. EGT also climbed more rapidly, and appeared to be about 200* higher. This was with the PDR35 turbo, and the Comp on 5x5. The thing smoked so viciously at low boost, that I thought the cars behind me were on fire. The ambient temp. was cold, around 25*f. The ambient temp appears to be a big player in the performance equation, since the IAT is now always reading ambient temp. Remember, air under boost is always much warmer, even when it is extremely cold outside. I'm not sure of the intercooler's efficiency, maybe someone else could chime in. I found that I could only run the Comp on level 3, if the ambient temp was below 40*. I just wasn't comfortable spinning the turbo that fast. I only left the IAT bombed for that day, and have since switched it BTO configuration. Frankly, with the high EGT, the obvious MPG decrease, (I didn't leave it switched long enough to calculate the mileage difference, but the boost, smoke and EGT can only mean one thing), I felt that It wasn't warranted with my present setup. If I could have gone 5x5 on the Comp, I would have left it bombed, since the power increase was definitely there. I'll try it again when I get my PDR40 on there, probably in a week or so. It's definitely a great warm weather bomb though. Thats pretty much it in a nutshell. If anyone has any specific questions, feel free to ask!



Rich

 

[jrobinson2]

The threads on the IAT I have in my hand apears to be 9/16-18 UNF.

Jared

 

[Steve Campbell]

jrobinson2.....

Thank you