Acceleration Problem

[Trog Dave]

I have an intermittent problem with an 04 2L HDI where the acceleration will occasionally be really poor/non-existent....I'm suspecting the accelerator pedal sensor because when the problem appears, it seems to accelerate normally using the cruise control....speed increases and instant mpg drops as you'd expect....at the same time. pressing the accelerator pedal fully to the floor (or to anywhere) produces no increase in speed or drop in mpg....is the pedal sensor a known fault and is there any way of testing it (for example, is it a potentiometer type device that I can measure)#

Thanks

[qman3428]

I have just had a similar problem, turned out to be the Mass air sensor, cleaned it and the sensor in the inlet manifold and the problem is cured. Mine didnt let me use the cruise control as the MIL came on. With regard to the TPS yes it is a potentiometer and this might help

http://www.ehow.co.uk/how_4489318_troubleshoot-tps-sensor.html

[Trog Dave]

If it was the mass airflow sensor, would it not report an engine fault? First thing I checked was the air filter and MAF....filter was clean and MAF slightly oily.

Also, if it was the MAF, would that not affect cruise control acceleation as well.

I'm suspecting the position sensor on the accelerator pedal itself, not a sensor on the engine/throttle body or equivalent....there is no mechanical cable linkage between the accelerator pedal and the engine....the pedal has a position sensor, wired presumably to the ECU

[qman3428]

The MAF can affect the performance without recording a fault, it should not be oily at all, there is also a second sensor in the air intake which is similar to the maf in design and talks to the maf, it too should be clean. The link I gave above shows how to test the TPS. If you want to be sure connect a lexia but cleaning sensors is free.