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392 IAT (long) sensor virtually cured my heat soak issue

21K views 50 replies 27 participants last post by  Rpaulg87 
#1 ·
Thanks to the posts put up by mikeyChallenger http://www.challengertalk.com/forums/f18/heat-soak-eats-20-lb-ft-torque-36973/ and rayzazoo http://www.challengertalk.com/forums/f5/mystery-grey-iat-sensor-connector-solved-63343/

My car is a dog in 85+ degree weather, esp with the A/C on, so I was really excited about trying the new 392 IAT sensor PN 05149279AB. It was $3.50 and plugged right into my gray connector and into my RoboFab air tube. Today was the real test as I go home for lunch, the car heat soaks, and I drive back in 90+ degree humid temps. The new sensor really made a difference I could feel. This is in the stock mounting location. Eventually I'll get the extension cable and relocate to the air box.

Thanks for the research guys as the heat soaking was one of my biggest complaints about the car. :bigthumb: I can't wait to see if cooler weather performance is better as well.

(I wanted to put something with a "heat soak" subject in this section for exposure.)
 
#3 ·
Sweet, I've read through the other threads and this looks wonderful. I'm going down to get one after work (or order it).

:bigthumb:
 
#4 · (Edited)
Wait so basically this is just longer and thus it gets the most accurate temp of the air actually entering the intake? So just the sensor and it connects right to where the current one does? Any adapter needed? Or just pn 05149279AB? Where'd you order it from?
 
#6 ·
Yes, browse through the other posts to get the full story, but basically the stubby stock IAT sensor heat soaks and gives false high reading. The new sensor with the extended arm put the tip in the middle of the airstream and gives a truer reading of the intake temps.

If you have the gray plug, the new IAT sensor plugs right in. Call your Dodge parts dept and see.......mine had it in stock.
 
#5 ·
Stopped at the dealer on my way home from work and got the new sensor. Drove home using torque to see 102 ambient air tmps and at one point then intake sensor read 180. Got home, swapped the new one in. Weather is supposed to be the same tomorrow so I'll test then to get accurate numbers for after.
 
#7 ·
Here are the two IAT sensors


Old


New

The new design insulates the wires and sensor better. I would compare the at idle temperatures between the two sensors and see which one rises more quickly and where they both stabilize at. Then compare this # with a thermocoupler reading like mikeychallenger did.

Great to hear this is working out. Also, I've got the parts to make a black to grey plug converter cable, I'm just waiting on parts to come in for the grey plug extension cable.
 
#9 · (Edited)
If I had to venture a guess I would say yes. The 2011 charger intake tube that I ordered to replace my 2009 tube (that has a resonator) came with the longer temp sensor installed in it already.
 
#13 ·
How exactly does a sensor fix the heat soak issue? Do the colder readings cause the ECM to add fuel?
 
#14 · (Edited)
What this modification does is improve the accuracy of the IAT reading. This results in your engine running more efficiently and ensures that you aren't loosing power due to detonation/knock and spark trim from a higher than actual temperature reading. A more accurate reading will cause the ECM to add the correct amount of fuel for the actual air temperature (ECM will calculate an air density) entering the combustion chamber.

Minimizing the effects of Heatsoak

Heatsoak Defined

Understand, heatsoak is not fixed because of this mod. Heatsoak is inevitable, especially once you shut off your engine, however, while your engine is operating, heatsoak is reduced through engine coolant. Measures we can take during engine operation are are using a 180 t-stat to start the cooling process sooner, reducing the fan settings, and using engine oil coolers. While at the track, you can use the 25 Cent Fan Mod to turn on the fans to cool off the engine when it's shut off.

We minimize the effects heatsoak has on engine performance (specifically the air entering the combustion chambers) by insulating the IAT sensor from engine materials that store heat and pulling air that is cooler than engine compartment air from the fender. We also can reduce the effects of heatsoak by using materials in the engine compartment that have low thermal conductivity and a high specific heat (e.g. rubber, plastic). A final way we reduce the effects of heatsoak on the IAT sensor is by relocating it away from the engine block.

These same principles listed above can be seen in the redesign of the 392 air intake tube and air box. The new manifold is a plastic composite material, the new air box is made of plastic, the sensor is insulated better than the previous and reads from the middle of the airstream, the sensor is located away from the engine block (the highest heat source), and the throttle body is thermally insulated by the new manifold that is a plastic composite material.


Effects of higher or lower sensor reading than actual air charge

With the heatsoak issue, if the sensor reads higher than the actual air going through the tube, it'll subtract fuel resulting in a less than efficient burn and also you'll be more prone to engine knock/detonation. This engine knock causes the ECM to reduce spark advance to compensate thus reducing the power output.

On the flipside, if you take the sensor and let it read ambient air temperatures (lxforum sensor relocation thread did this), this won't be representative of the actual air going through the intake tube. As a result, you'll have too much fuel added and a less efficient combustion. This is also the reason why too much fuel is added as a result of a sensor that gets dirty or oil on it.

The argument has been that the IAT sensor relocation mod tricked the ECM into adding more fuel when in reality, as MikeyChallenger has shown in his thread 20+ lbs/ft torque, allowed for the ECM to read the actual air temperature flowing through the tube rather than the heatsoaked temperatures of the materials surrounding the sensor, resulting in a more efficient burn. This also helps to explain why the transmission shifts are smoother and the acceleration lag is nearly gone because of the new sensor.

Also for reference, An air temperature charge pulled from the fender well is about 4-5 degrees above ambient and the air temperature charge pulled from inside the engine compartment is 10-15 degrees above ambient. At highway speeds, I've shown that an unshrouded short ram intake can read 1-2 degrees difference from a fender pull intake.
 
#15 ·
I think I'm going to stop by the dealership and pick one up. When its muggy outside my car feels like its down a cylinder.
 
#16 ·
It does make a noticeable difference on the 6-speeds as well.

How many times will you say "I only spent $4.00 to make my car run better." ?
 
#17 ·
I'll swing by the dealer for one as well. I have yet to pick up a 180 stat, but that will come soon enough. Anything that will help offset the heatsoak effects will be a welcome addition.
 
#18 ·
AWESOME! I was about to drop 400 bones on a diablo and Tstat. I'm going to try this first! Whoever figured this out I owe you a cheap light domestic beer!
 
#19 ·
while this will help, it wont be as effective as the tstat/fan mod. that mod brings down engine temps, which in turn keeps timing from being pulled to begin with. overall it keeps engine bay temps lower and will help the IAT sensor from being effected.
 
#20 ·
Thanks to the posts put up by mikeyChallenger http://www.challengertalk.com/forums/f18/heat-soak-eats-20-lb-ft-torque-36973/ and rayzazoo http://www.challengertalk.com/forums/f5/mystery-grey-iat-sensor-connector-solved-63343/

My car is a dog in 85+ degree weather, esp with the A/C on, so I was really excited about trying the new 392 IAT sensor PN 05149279AB. It was $3.50 and plugged right into my gray connector and into my RoboFab air tube. Today was the real test as I go home for lunch, the car heat soaks, and I drive back in 90+ degree humid temps. The new sensor really made a difference I could feel. This is in the stock mounting location. Eventually I'll get the extension cable and relocate to the air box.

Thanks for the research guys as the heat soaking was one of my biggest complaints about the car. :bigthumb: I can't wait to see if cooler weather performance is better as well.

(I wanted to put something with a "heat soak" subject in this section for exposure.)
I ordered mine today. you mentioned an extension for the wires where do get one of these extensions? what is required to i.e. drilling etc to mount in the Air box? how does one Fill in the hole left in the intake?
 
#21 · (Edited)
MikeyChallenger, the 20 lbs/ft thread modified his stock airbox with the extended wire setup during his testing. You should shoot him a PM on the questions you have above but you will drill a new hole in your airbox and you will plug the old hole.


I posted this on another thread but here's the raw data and analysis behind doing this $4 modification. It's probably the best $4 you'll spend to improve the driveability of your Challenger. For those needing a black to grey plug converter cable, I am making those for $21 + $7 shipping so just shoot a PM for details. Now if you have a grey connector and want to extend it, you'll half to stick with cutting and extending it for now as the parts aren't available to make them right now.



The purpose of this test is to determine which air temperature sensor reads more accurately to the actual air entering the engine.

Ambient Air Temperature: 94 degs
Intake Tube Temperature: 155 degs (radiator fans off), 175 degs (radiator fans on)

So analyzing the graph. At the start of the WOT run, while cruising prior to, there is an IAT delta of 7.2 degs between sensors. At the end of the WOT run, there is an IAT delta of 15 degrees between sensors. This delta results in more engine knock with the old sensor. At the end of the WOT run, with a 0 % acceleration, the old IAT sensor reading is continuing to ladder down while the new IAT sensor is at a level temperature. This is a key indicator on sensor reading accuracy and whether or not the sensor is reading the air temperature flowing through the tube or is inflated by the intake tube materials surrounding the sensor.

So here's a situation where the new sensor is reading a lower temperature than the old. The old sensor causes PCM to think that the air charge is not as dense than it actually is, so it trims fuel when in reality the air going through is more dense. The result of improper fuel matched with density of air causes detonation resulting in knock. This knock results in spark trim thus reducing power (more commonly known as torque).



In another situation, here is regular acceleration in city driving. There is a IAT delta of 5.4 degrees. The delta results in more engine knock with the old sensor again. So here's a situation where the new sensor is reading a higher temperature than the old. The old sensor causes PCM to think that the air charge is more dense than it actually is, so it adds fuel when in reality the air going through is less dense. The result of improper fuel matched with density of air causes detonation resulting in knock. This also results in the lag we feel as now we have an air/fuel mixture with too much fuel and then we get that sudden surge in the throttle. It also helps to explain why the new sensor provides that "butt dyno" smooth acceleration feeling.



Now it could be argued that you can adjust the tune, add/subtract fuel to get rid of the knock at WOT and adjust the part throttle tune for normal acceleration.

At WOT, the old sensor reads higher than actual temperatures, doesn't add enough fuel so now we increase fuel and our problem is fixed. At the 1/4mi track, this explains the "heatsoak" effect. As we do consecutive runs, our IAT sensor continues to read a higher than actual intake temperature. We start to get more engine knock with each progression. Now, we have two ways to fix it. Take an accurate temperature reading so the PCM can determine the proper fuel mix all the time, or we can continue to adjust the fuel tables ourselves for each consecutive hot lap.

At normal acceleration, we adjust the throttle to allow more air to go through to compensate for the PCM adding too much fuel during normal driving conditions. Either that or we accidentally add fuel thinking that there's not enough and in hopes to reduce knock. Another is that we trim fuel. All of that trouble when we could have just increased the accuracy of our IAT reading with a new sensor.
 
#22 ·
#24 ·
I made yet, another, batch of black to grey converter cables for those wanting to do this mod and sent out 6 already. I have 4 left so PM if this is something you need for a plug and play solution. Cost is $21 + $7 shipping/fees.
 
#28 ·
In short yup plug and play. If you have the black plug connector, I make a converter cable that is plug and play.
 
#30 ·
Thank the Mopar spirits for the RT gray plug! :)

Also, thank you to rayzazoo for setting me straight about the plug, and not just selling me a cable after asking for one. :)
 
#31 ·
For those still needing a black to grey converter, I do have 4 left. I think this will be my last batch. PM me if you're interested.
 
#33 ·
My 09 SRT is black.
 
#35 ·
subscribing so I can read this in the morning
 
#36 ·
#37 ·
Thanks to the posts put up by mikeyChallenger http://www.challengertalk.com/forums/f18/heat-soak-eats-20-lb-ft-torque-36973/ and rayzazoo http://www.challengertalk.com/forums/f5/mystery-grey-iat-sensor-connector-solved-63343/

My car is a dog in 85+ degree weather, esp with the A/C on, so I was really excited about trying the new 392 IAT sensor PN 05149279AB. It was $3.50 and plugged right into my gray connector and into my RoboFab air tube. Today was the real test as I go home for lunch, the car heat soaks, and I drive back in 90+ degree humid temps. The new sensor really made a difference I could feel. This is in the stock mounting location. Eventually I'll get the extension cable and relocate to the air box.

Thanks for the research guys as the heat soaking was one of my biggest complaints about the car. :bigthumb: I can't wait to see if cooler weather performance is better as well.

(I wanted to put something with a "heat soak" subject in this section for exposure.)
Wait a minute, you just bought the regular 392 IAT sensor and it plugs into both the grey plug and the intake tube? I'm confused. Why does Rayazzo have these specially made adapters? Do you have to splice the wires and do it that way, or is it a direct plug into the grey plug (on 09 10 RTs.) Thank you. I am very much interested in this mod.
 
#38 ·
I don't have a modified intake and the 392 IAT Sensor plugged right into the stock connector and mounting location on my '10 R/T.
The adapters he makes can solve issues with a different connector, the need for a longer wire to relocate the sensor further from the stock location (some CAI's I assume), or both.

For the price I figured I had nothing to lose.
 
#40 ·
Thank you for the clarification. So since I have the grey plug (I have a '10 R/T), I can just buy the 392 sensor from the dealership and plug and play? Very nice, I will have to stop by Baxter next week and get me one of those. Would love to battle against heat soak.
 
#41 ·
wow i cannot believe i only just found this thread i am going to do the mod and see if it will help with my 09 challenger pulling hard under boost in very hot as well as cold conditions
procharger 7lbs of boost 6.1 liter
 
#42 ·
You'll need the adapter cable (gray connector) to use the '11+ style IAT. The '08-'10 SRT 6.1s have the black connector.

One of the members on the forum made adapter cables to allow the mod.
 
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