Challenger IAT Sensor

[oemtech]

Johan,

This was posted over on Challenger Talk....

Does anyone know what the part number is for the SHORT air intake sensor.. I have a 09 srt.. i pulled it out pitched it and bought the long one.. Well I found out that that is NOT something we should be doing. I talked to Johan at Diablo he says it is a waste of time and actually messes with other stuff. So does anyone have the part number so i can reorder the original one i had?

Care to enlighten us as ti why?

[Mike_Levy]

Probably because its blocking air flow. Why anybody would go to a LARGER IAT is beyond me. Why would you try to block the flow through the intake pipe?

[oemtech]

So why did Dodge switched to the long probe in 2011? This is blocking air? I would think you would be getting a much better IAT reading than one a 1/2" away from the edge of the intake tube.





According to CT this is what Johan said...

It is no good because its transfer function for converting temp to volts is not the same as the stock one so your pcm is not getting an accurate reading of what your air temp really is.

The next time I am out to my shop I will pull my short IAT sensor and and data record both long & short and see if there is any difference.

[Mike_Levy]

Okay, if thats what Johan said, then thats the problem.

[oemtech]

Okay, if thats what Johan said, then thats the problem.

Johan may be a hell of tuner but I would love to see some data.

So now for some Sam Spade work....

IAT Probes







As you can see from the previous photo the IAT has gone from no probe protection to a covered version. It is a bit hard to tell from the photos that the short one has a much thicker probe guard that the longer version.

Probes installed in TB/Air Box elbow





Next session is to data log both probes on the same driving circuit. This will take 2 days as I what to try to duplicate the runs from a cold start.

[mikel]

You guys are looking at this entirely wrong.

they are 2 different sensors, and chances are, they have 2 totally different output values (transfer functions), for example, if IAT1 says 3V = 100*, but IAT2 says 3V = 150*, well, like Johan said, it will cause problems

Ideally, swapping 0-5V sensors from application to application is not a good idea, unless you know their transfer functions are the same.

[Mike_Levy]

The smaller one is the one I had in my 300 and Jeep SRT8s. On the Jeep somebody cut the protector off and it still seemed to work fine.

[oemtech]

Well I set up a test gauge/log on my Trinity and recorded 2 runs a day apart. I started and ending the log in my garage.

2010 Challenger 5.7L
Cervini CAI with function air scoops
180° Stat
15 mile route
mixed driving - start/stop, hwy, frontage road
9 am start time
61° temp Dec 16, 2012 (long IAT test)
52° temp Dec 17, 2012 (short IAT test)

The 2 runs produced the results I suspected. The IAT's were almost Identical except the short IAT reacted quicker to heat soak. If in fact the IAT probes register different temps based on voltage readings as Mike Litisch says then Dodge, after market suppliers and tuners have a potential problem. It means they must know which probe is being used and adjust the tune accordingly. Also Dodge would have somehow restrict the sale of probes to the customers as it could effect how the engine runs.

Bottom line.... I am raising the BS flag.

Long IAT - Start


Long IAT - Finish



Short IAT - Start


Short IAT - Finish


Here are the Trinity logs. It should be noted that I added the speed and rpm gauges to the short IAT for reference.

[mikel]

Well I set up a test gauge/log on my Trinity and recorded 2 runs a day apart. I started and ending the log in my garage.

2010 Challenger 5.7L
Cervini CAI with function air scoops
180° Stat
15 mile route
mixed driving - start/stop, hwy, frontage road
9 am start time
61° temp Dec 16, 2012 (long IAT test)
52° temp Dec 17, 2012 (short IAT test)

The 2 runs produced the results I suspected. The IAT's were almost Identical except the short IAT reacted quicker to heat soak. If in fact the IAT probes register different temps based on voltage readings as Mike Litisch says then Dodge, after market suppliers and tuners have a potential problem. It means they must know which probe is being used and adjust the tune accordingly. Also Dodge would have somehow restrict the sale of probes to the customers as it could effect how the engine runs.

Bottom line.... I am raising the BS flag.

Long IAT - Start


Long IAT - Finish



Short IAT - Start


Short IAT - Finish


Here are the Trinity logs. It should be noted that I added the speed and rpm gauges to the short IAT for reference.

if they were different, and dodge used them in different applications, they would account for that in the software....

I simply said 'chances are they are different', I didnt state any facts there, so no need for the BS flag....

If they are selling it as a replacement, then yes, they would be sure it had the same transfer function or it would be an issue.