4.2tdi boost control
 

My car seems to continue accelerating after releasing the throttle. Is this a boost control issue? I've no fault codes on OBD.

Where is the controller on the 4.2tdi? Might this explain my low mpg?

Sounds daft this ............ its not the floor mat fouling the pedal at all ??

Has this fault developed over time ?
Has this fault come on since the re map you had done ?

Not daft at all, it happened to me recently.

Who done your remap??

Thanks for your replies.

It's been since I've had the car. Both before and after the remap. The mats ok.

Map was done by Expert Tuning. He's the guys who gives the course to Quantum tuning guys. I've used him a few times- really excellent.

So it had the issue before any tuning work ,reminds me of a software or programming glitch a little....definatley not had any tuning work done before you got to it .
How many miles on it ? does it black smoke when you put your foot down ?
Oil level ok .......not overfull at all ?
You say fuel consumption not very good ....how bad ? could be weeping injectors normally get a bit of diesel knock though or heavy smoking on start up aswell .

I cannot see it being the boost ......... boost is just air you need fuel present for the engine to carry on going .

Have you vcds ............ go into accelerator position sensor ....it may show as two tracks .......one track volts start low and go up , the other track start high and goes down or it may just show as accelerator percentage .

With throttle pedal released percentage should be low , with ignition on only press pedal all way down and back the volts or percentage should be a smooth transition up and down .

Will have to have a think on this one .

Thanks for your reply.

There is no smoke at all on start up, drive or on full boost. Infact exhaust tips shiny and clean.

Oil being changed on Friday while the DPF's are removed so will see if that makes a difference.

Don't think it was mapped before.

Fuel consumption around 29 on a 70mph cruise controlled run. Yet to see an average over 30- current average 27.8

In the process of sorting VCS should be by the end of the month.

Just a thought do they have dump valves of any sort? Perhaps it's not releasing boost on overrun?

Have you checked the oil level?

29mpg doesn't seem bad to me for a 4.2

With regards to accelerator percentage in vcds - my car is showing 15% with foot off the pedal is that normal or should that be closer to zero?

Can I ask those of you with a 4.2tdi what you cars idle speed is both in neutral and drive.

Thanks