I'm new to the ECU world and wandering how folks go about getting the calibration data for the various engine sensors (IAT, TPS, MAP, Crank etc) to feed their aftermarket ECUs?

By calibration data I mean the value vs voltage relationship such that, for example, the ECU knows that when a specific MAP sensor says 2.34 volts it means 200 KPa or that a coolant sensor means 127 degrees when reading 4.21 volts etc.

I've been recommended to buy a number of "known" sensors for my ECU, which to be honest just seems a little nuts when the current OEM ones hanging off my Duratec work just fine.

Have I just misunderstood something?

Any advice?

[Edited on 6/11/20 by GrahamC]

Most ECU software has a library of common sensors. If not then you will need to calibrate them. There is calibration data for many sensors on the web. If not they are almost always linear so you will need two calibration poits - temperature sensors are a doddle ice and boiling water. Pressure sensors - not so easy but doable.


Other sensors like crank position will be configurable in the software.

You can go on the Motec website (maybe many ther ecu manufacturers do the same) and download the software for free for their older ECUs. Probably a very good idea to play with the software to decide which ECU you want to fit.

It is pretty easy to set up an aftermarket ECU

Most temperature sensors are thermistors (coolant and air) and are quite none linear, i start with a pan full of ice water, a thermometer and sensor in the water and the sensor connected to the ecu with live data running. Slowly heat the water to boiling adjusting the temperature points as it goes up in the ecu software so the ecu reads the same as the thermometer. I find it's well worth the time to get right.

Thanks for this info, really appreciated.

Took a look at some of the datasheets on the Motec site and that is exactly the type of info I was looking for.

I think in my case its the MAP, IAT, and coolant temperature that are my issue so will endeavour to track those datasheets down or do the ice/heat thing with the temp sensors and work it out myself.

I clearly need to do some learning.


I'm running a normally aspirated setup on a single large(ish) throttle body (plenum came off a Caterham 420r) and have understood that I might be able to bypass the MAP altogether and just tune based on TPS, again would welcome any advice.

Normally aspirated is absolutely fine just running a TPS. It's nice to run a baro sensor though, compensate for altitude/pressure and it just makes everything nicer for general use, not so important if it's just flat out racing.

some other sensors are available here: https://www.etbinstruments.com/index.php?route=product/category&path=100

Omex have some fair prices for some here too- http://omextechnology.co.uk/page145.html

and some more here- https://www.race-technology.com/gb/racing/products/sensors

You generally get what you pay for.

Though I've recently replaced a VDO 1 wire oil pressure transducer (which is circa £60), with a 3 wire chinese special from e-bay
https://www.ebay.co.uk/itm/1-8-NPT-Pressure-Transducer-Sender-Sensor-Stainless-Steel-for-Oil-Fuel-Air-Water/383204893026?ssPageName=STRK%3AMEBIDX%3AIT &var=651739860460&_trksid=p2057872.m2749.l2649

And it's great. Linear and repeatable performance, no glitches. It's feeding my Dash2 rather than the ECU, but still may be useful.

quote:

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Originally posted by IanmK
Though I've recently replaced a VDO 1 wire oil pressure transducer (which is circa £60), with a 3 wire chinese special from e-bay
https://www.ebay.co.uk/itm/1-8-NPT-Pressure-Transducer-Sender-Sensor-Stainless-Steel-for-Oil-Fuel-Air-Water/383204893026?ssPageName=STRK%3AMEBIDX%3AIT &var=651739860460&_trksid=p2057872.m2749.l2649

And it's great. Linear and repeatable performance, no glitches. It's feeding my Dash2 rather than the ECU, but still may be useful.

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Yeah just to confirm, IAT and CLT sensors are usually *very much* not linear and you'll need to do a good number of temps between freezer temp (-20) and boiling if you want it to run right in all weathers.

Pressure sensors are usually linear.

Other sensors are usually quite specific and the ECU software will either have compatibility, or not, as it needs to be hard-coded, such as wheel decoders for timing.