Thread: Exhaust Gas Temperatures Readings Questions

D4 SDV6 here.

Was playing with my IID2 gadget monitoring engine parameters while driving, specifically some parameters I thought associated with the ERG's namely:

ERG valve position Bank 1 (% open)
ERG valve position Bank 2 (% open)
Exhaust Gas Temp Bank 1, sensor 1 (C)
Exhaust Gas Temp Bank 2, sensor 1 (C)

When driving, both ERG valve positions appeared to open and close in sync with each depending on engine load and throttle position etc. Positions changed within a range of ~4% to ~90 %. I thought this behaviour was normal and logical.

However, both exhaust gas temperature sensors gave reading which were not in sync with each other, which I thought was not logical, perhaps indicating a problem with a sensor or my understanding of what these temperature sensors actually measure. To my mind they should have mirrored each other if they are supposed to measuring the same property (exhaust gas temperature) only on different cylinder banks.

'Exhaust Gas Temp Bank 2, sensor 1' would vary up and down within a range of ~150C - 300C inline with changes in engine load. It appeared to be behaving logically. That is smoothly heating when engine load was increased and smoothly cooling down when engine load was reduced.

'Exhaust Gas Temp Bank 1, sensor 1' stayed fixed at ~120 C except under heavy load (up hill) and wide open throttle positions in which case it would spike very quickly (within 2-3 seconds) to peak at temperatures of ~300 C before slowly falling back to ~120 C (over ~10secs period) once the engine load was decreased.

It was like the temperature sensor on Bank 1 was only being exposed to hot exhaust gas under certain conditions whereas the sensor on Bank 2 was being exposed to hot exhaust gas all the time.

Does any body know where these temperature sensor are located. That is, is the behaviour of the two temperature sensors explained by the fact they are not really in identical positions on each bank and so are not really measuring the same thing. Or is this behaviour more indicative of a failed sensor on Bank 1.

If an exhaust gas temperature sensor has failed does it have any effect on engine performance or do the sensors just exist to raise alarm conditions in response to excessive exhaust gas temperatures.

The primary is on the left bank on the 3.0 TDV6/SDV6 and the secondary on the right, whereas on the 4.4 TDV8 the primary is on the right bank and the secondary on the left bank.