Does anyone have the ability to get me the operating range for the stock IAT sensor? Voltage and resistance

Mercedes: 651 153 0028
Standard: AX129
MOPAR: 5174042AB

I've called 6 MB dealerships and no one wants to help

 

I'll see what I can find for you. BTW I've found a way to mount the stock sensor in the surge tank runner using a brass fitting and circlip. Can't post pics from my phone Ill for it later when I'm home.

 

I'd love to see that actually!

To give a little more clarity on my request, I want to use one sensor for both my datalogging and my ecu input. I have the Zeitronix sensor and I want to see if this operates within the same range as the stocker. Not likely, but it's worth a shot. If I have to run two, I would prefer to move the stock sensor further downstream so those pictures would be nice

 

Yes, please post pics! Sorry for the stupid question, but what is the benefit of moving the IAT sensor for its OEM location?

 

This would be a more accurate representation of the air temperature going into the engine. In the stock configuration, the sensor essentially reads the temperature of both banks and uses it as an average, safer than one sensor in one bank and cheaper than two IAT ecu inputs (the SLR uses two IAT inputs).

For my application, the sensor isn't realizing the cooling effects of my water injection well enough because I flow too much air. With the sensor closer to the engine, it gives the water a chance to mix with the air more completely.

 

Here's what I found for you.
Its an NTC resistor. The resistance drops with increasing temperature.
ECU sends 5v signal and monitors the return voltage on the other wire.
20C/68F = 2.7v
40C/104F = 1.8v
60C/140F = 1.1v

Polarity of the sensor itself is not important/random.

Resistance of the sensor:

68F = 5800-6300 Ω
86F = 3700-4110 Ω
104F = 2500-2700 Ω
122F = 1700-1850 Ω
140F = 1100-1350 Ω
158F = 800-920 Ω
176F = 550-700 Ω

 

This is my second IAT location. I am still testing so I don't have any announcements yet, but I believe the stock IAT location is getting wet when spraying meth and causing a large temperature drop after letting off the gas, as the liquid evaporates off the sensor. Likewise during boost/spray, the sensor is being coated with the water/meth and reading the temperature of the liquid, not the actual air temperature. I wanted to verify the actual air charge temp by eliminating this possibility. Hopefully moving it farther away directly out of the spray will be more accurate. I still have the factory IAT installed to easily switch back to to prove my theory.

 

I connected my zt2 to the iat line and I was getting voltage, I contacted dashdaq and they told me they needed the voltage to degrees to make a formula for it, this seems like what they need

 

This is AWESOME work! I'll likely do the same thing as you have soon. Originally, I wanted to run only the aftermarket IAT sensor provided with the ZT-2 as it's likely a higher resolution. With how effective that relocation looks to be, I may just run both anyway to prevent 'noise' in the system... stock for ecu and aftermarket for ZT-2.

I had the same suspicions with regard to the water to close to the IAT. Then again, you know this because we've been texting (just realized it was the same screen name). I'll be installing all of my datalogging equipment this weekend, hope to get you an update

I have the resistance tables for the sensor provided with the ZT-2. This was quite a pain in the *** to get out of Zeitronix because it doesn't sound like they want it shared with the public. I can respect that but since I bought the product, I see nothing wrong with getting all of the needed specs so anyone with a ZT-2 feel free to PM me for the table if you need it. What I CAN say is now that GreaseMonkey has provided the resistance values, I see that these two sensors would not be interchangeable. The aftermarket sensor has FAR more resolution so its scale is greater.

 

I mean I hardwired into the iat sensor wire from the ecu, on one of my user inputs for the zt2 and when I was talking with dashdaq they said they needed the values for example what 1 volt is equal to in degrees so they could do the math equation via dashdaq via their SW and we could use a signal via zt2 instead of obd

 

Yea, I understand your situation. My goal was to use the aftermarket sensor for both the ecu and the ZT-2 but that will not work. Using the stock sensor for both inputs can work, but you'll have less resolution capabilities for your ZT-2 and the risk of noise in the signal system. Still effective though

 

Now if only we can get the right calculation for the rescale calculator in dashdaq, I'd rather just have timing off the obd

 

I'm watching this thread. I'd like to have IATs update in real time instead of the OBD stair-step.

 

I have a GM temp probe on one surge tank and I have a gauge display in the cabin. Simple and easy.

Some guys also relocated the ambient temp display on the surge tank and get the IAT reading on the dash.

 

I think the ambient temp sensor reads too slow for this application. But who knows until you try it. Bad weather here (heavy rains) has slowed down my testing with the relocated IAT sensor. It appears to be working good so far.

 

Best thing I've found if you are looking for values is to use OBD 2 readings, connect volt meter and if possible use a power supply to vary input voltage from 5V down to 0V. You can then get a good correlation between the two.

If you have none of these then use input from Dashdaq/ZT to log a voltage reading and temp reading via OBD from cold to warm ... You can extrapolate the curve on each side.

 

No tried the using the obd and using voltage, it doesn't work, user input is very fast, it might go up or down but obd is the same

With what greasemonkey has posted I'll contact dashdaq and see of they can come up with an equation for the rescaling calculator

 

Wish this thread kept going, some interesting stuff here. Was hoping to see the results by greasemonkey after the relocation of the iat vs the readings in the stock location with spraying meth.

 

In my tune temperature correction has been eliminated . Only way to get away with that is to know exactly what your IAT's are under all conditions or you can damage the engine.
Mine was pulling timing way to much for really no reason so it is set up like this now and will hold 21-22 degrees timing nice and solid now.
Nitrous also wrecked havoc on the IAT reading's just like Meth does in some circumstance's.

 

Interesting, so moving the iat sensor into the intake manifold plenum, has helped with your timing making it more stable? What about your temperature readings do they differ much from in the stock location spraying meth vs the new plenum location?

 

Just realised this made no sense @sicamg amazing your tune disregards the temp so nice to see that kind of timing all day long. I am in the process of relocating my IAT sensor into the intake plenum I am getting massive timing pull due to high temps as the meth bends around the stock location and believe the relocated sensor position is going to be seeing true air temp before hitting the cylinders. Very excited for the results to come.

 

There is no reason I see why this alone would not at least modestly work, to avoid the spray cooling problem. A second sensor is needed for logging and other purposes anyway really.

Only other improvement would be to find a sensor that can output same voltage ratios for the ECU to see. Maybe it would be quicker.

But getting more accurate readings on stock temp probe in ECU expected ranges would be best.