Differential Pressure Transmitters in Automotive Applications

[peterlow]

A quick question hopefully here. Basically just want to know how common it is to use differential pressure transducers in the automotive industry and if they are used someone could point me in the direction of some good automotive industry standard low pressure DP's.

 

[Tmoose]

Some Fuel injection systems use a manifold pressure to make decisions. At full throttle manifold pressure would be nearly atmospheric. I think systems that use Mass airflow sensors are the opposite of what you want. I heard that Acura may have switched from one type to the other recently. Early Bosch systems had a manifold pressure sensor .

http://www.icbm.org/erkson/ttt/engine/fuel_injection/d-jet.html

Not a transducer, but MG 1100s and real mini coopers had a differential oil pressure switch to turn on a light if the oil filter was getting plugged. Probably because the engine and trans shared the sump, and are allergic to each other's unfiltered byproducts.

 

[OP800]

Ford 4.6 and 5.4L mod motors use a DPFE to measure exhaust pressure accross a restriction in the EGR pipe to tell what the flow conditions are for EGR gas recirculation.
It is a 0 to 5 volt device.
This detects any loss of pressure due to a leak, excessive pressure, plugged EGR port and inop EGR valve circuit.
All logic driven for results.
The PCM routine calls for pulewidth driven signal to the vacuum gate that operates the EGR valve to a known opening and flow rate. The routine then measures for an expected result of a flow test from pressure detection by the DPFE. If out of limits, a DTC code is set and the check engine light comes on.
When the engine is first started, the device is addressed to see if there is excessive flow indicating a cracked/rusted pipe, a hose off etc. A blocked exhaust system can even cause excess pressure and be detected since the EGR is not open at this time.
Device is not very large and is connected with short hoses on the EGR stand pipes located each side of the internal restriction.
Within a combination of routines, hardware configs and expected reaults, an inferred result is registered in a table as either a pass or fail.