Refurbish antique diesel engines with modern parts

Sensors and Such

The turbo controller will need a handful of sensors to help it think about things.

For development I’m planning to use a throttle position sensor (TPS), exhaust gas temperature sensor (thermocouple interface), a manifold pressure sensor (MAP) , an exhaust gas pressure sensor and some kind of engine speed/RPM input. Some or all of these might end up in the final product. It’s hard to know until I start testing the code on my engine dyno. For development I may also use two air intake temp sensors (at compressor outlet and at engine intake) and a water temp sensor.

For the moment I’m testing a few different MAP sensors and a few EGP sensors. I’m looking for inexpensive sensors that are readily available that have 0-5volt analog outputs and an appropriate pressure range.

For the MAP sensor I think I’ll go with the older 3 bar GM style sensor. It’s unfortunate that ~33% of it’s functional range will basically be useless in a diesel application. (The Toyota 3B does have a throttle plate and being able to sense intake vacuum may end up being a benefit for implementing an exhaust brake with the VNT turbo.) I’ve measured and mapped the output signal from 0 PSIG to 30 PSIG and it’s fairly linear. The only deviation from linear in my measurements could be attributed to my digital pressure gauge’s range. I was able to verify from my measurements that the transfer function in my sensor does match the formula I found in the AEM Electronics forum. That formula is (volts * 10.906) – 14.53 = PSIG.

I also have mapped out the exhaust pressure sensor used on the 2006-07 Ford diesels. (This sensor is used in many other applications too.) This 5v sensor operates up to 40PSIG which should be plenty for my application. I don’t think the turbine should need to be driven by more than 40 psi ever. Excessive back pressure would just create excess heat. I calculated out a transfer function for this sensor to be: volts= (PSIG/10.906)+1.35. You can rearrange this function to calculate PSIG from an input voltage. From measurements I’ve verified it to be accurate within less than .5% of the measured voltage on my sillyscope.

Why am I messing with an exhaust gas pressure sensor? I’m not planning to do EGR which is part ofthe reason most production vehicles use one. Or they use it to help control an exhaust restriction valve to aid in engine warm up. I’m using one for development to study different VNT turbos. I want to know how much drive pressure it takes to generate certain boost levels vs. RPM and VNT blade angle. I may find that having an EGP sensor will be a beneficial input for production versions too. Hard to know this early in the process. It will certainly be helpful to develop the code for an exhaust brake function.

My sensor test setup. I used the PVC pipe as a buffer tank for air pressure. It helped make the process of taking measurements much easier.

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