AEM temp sensor scaling

Discuss which Sensors work best with these ECUs and share how you are using inputs and outputs
Simon P.
Posts: 96
Joined: Sat Nov 12, 2011 6:24 pm
ECU Model: S100 Pro
Firmware Version: 61
Location: Montreal, Canada

Re: AEM temp sensor scaling

Post by Simon P. »

Shit, I'm an idiot! :shock:
Stevie, you're 100% right I think...Although I'll have to test it out, I'm pretty sure you're right! When looking at the wiring sketch from the AEM forum, that threw me off as the guy was using an external 5V power source to a 2.2k pull up. So I wired it the same way, not realizing that the DTA input is the 5V with it's own 1K pull up...
Let me test it out but for some reason this seems right...
The way I had wired it up the sensor output gave me 4800mv at ambient. This seemed off from Jon's scale. In order for it to be correct, the scale pull up value would have had to be in the 700ohm range.
Now the way I had it wired, both pull ups were in parallel to the signal line. The parallel sum of the DTA's 1K and my external 2.2k is 688ohm. Very close to my estimated 700ohm in the previous paragraph... Which seems to confirm just what you said Stevie; I wired the external 5V and 2.2k pull-up for NOTHING!!!
I'll let you guys know...
Thanks again very much.
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ignitionautosport
Posts: 577
Joined: Wed Jul 27, 2011 5:30 am
ECU Model: S80 Pro
Location: New Zealand
Contact:

Re: AEM temp sensor scaling

Post by ignitionautosport »

Yeah you only need the external pull-up if wiring to an AV, AT's have it built in as discussed.
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Jon K
Posts: 602
Joined: Fri Dec 04, 2009 1:45 am
ECU Model: S80 Pro
Distributor: DTA UK
Firmware Version: 73
Location: Pennsylvania, USA
Contact:

Re: AEM temp sensor scaling

Post by Jon K »

Simon P. wrote:Shit, I'm an idiot! :shock:
Stevie, you're 100% right I think...Although I'll have to test it out, I'm pretty sure you're right! When looking at the wiring sketch from the AEM forum, that threw me off as the guy was using an external 5V power source to a 2.2k pull up. So I wired it the same way, not realizing that the DTA input is the 5V with it's own 1K pull up...
Let me test it out but for some reason this seems right...
The way I had wired it up the sensor output gave me 4800mv at ambient. This seemed off from Jon's scale. In order for it to be correct, the scale pull up value would have had to be in the 700ohm range.
Now the way I had it wired, both pull ups were in parallel to the signal line. The parallel sum of the DTA's 1K and my external 2.2k is 688ohm. Very close to my estimated 700ohm in the previous paragraph... Which seems to confirm just what you said Stevie; I wired the external 5V and 2.2k pull-up for NOTHING!!!
I'll let you guys know...
Thanks again very much.
Crap - I didn't realize you were withing the 5v in external. Follow the spreadsheet as the 1K pull up to 5v is internal.
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