Throttle body

[Paul Davis]

I have been suffering with acceleration lag, no faults, live data for all sensors look good. The only one that I suspect not in range is the throttle body. When I accelerate the throttle body opens for a few seconds and then shuts while still accelerating. I have changed the IMRC sensor, but now the throttle body is almost fully open at idle with engine at temperature. What is the electronic relationship between the APP sensor and the throttle body. Should the throttle body follow the APP sensor position I.e APP at 0 TB at 0, APP at 50% TB at 50% etc

 

[Pale]

You've got a diesel? As far as I'm aware the throttle body (the butterfly valve position) is closely related to engine power in gasoline engines, but in diesels it functions a little differently - the engine power depends on the amount of fuel injected, so your APP sensor should be the ECU's reference for amount of diesel fuel to be injected. A diesel engine doesn't actually need a throttle body, it would operate just fine with it wide open 24/7, but in modern diesels it's not unusual to see a throttle body, it being used for improving emissions and the like.

 

[Paul Davis]

Yes it is a diesel. Just can’t understand why the acceleration is so bad. If the revs are at 2000 rpm and I accelerate with 100% throttle nothing happens, but if I take my foot of the accelerator and back to full throttle the car will accelerate as should. It seems though it is lacking something on the initial acceleration.

 

[F6HAD]

Sounds like a slow operating or leaking egr valve, pretty common on these. Solved with egr off solution.