My 525d intermittently feels like its holding back/jerky when accelerating or at a constant speed.

The car's been to the dealer several times and no fault has been found. Several people have mentioned it could be a problem with the EGR or air flow sensor. Problem is, since there's no fault code, is there anyway of testing these parts to know if they are faulty other than switching one from another car?

Thanks,

Steve

 

The jerky acceleration could be due to some other reason - a fuel pump, air filter, to name a couple. If this is a serious enough problem to justify a full-on investigation, I advise you take the car to a reputable indie mech. and have it thoroughly checked.

 

I have the same issue as you and have had in the past.
In the past the dealer eventually cleaned out the air filter and the EGR valve. This cured it.
It came back a while ago so I decided to take the EGR valve off myself and clean it. Time consuming job (you have to take the inlet manifold off) and very messy.
Cured it for 2 days and then it came back so I think something else in the EGR mechanism is faulty. Next time it's in the garage I'll ask them to check.

 

You could remove the MAF sensor and then try how the car performs. Detaching the sensor will make an error code, but you would be able to see if that's the reason for hesitating. The MAF sensor will get dirty in time and therefore give faulty info to ECU. If it's the MAF, then you could buy a new one or try to clean the original.

Take a look here.

- Antti -

 

Ok, thanks.

Car still under auc warranty so don't want to mess about with it myself, especially since I don't know what I'm doing However, will be putting these suggestions in front of the dealeer next time its back in as they seem to have given up

Any other ideas?

Thanks.

 

Steve, i get something similar with my 55 plate 525d. In my case it is the dpf cleaning cycle, the exhaust note sounds slightly deeper and the car gets very hesitant/jerky, its not normally too bad, however if it kicks in and i dont let it complete the cycle then for the next few journeys then the same symptoms present themselves. When i feel it kicking in i just drive on for a few miles and since i found this cure it sems to be rarely any problem.

Cheers.

 

Interesting, and thanks for your feedback...so how long does the cycle take? Is this a set time or number of miles? How frequently would you say this happens?

I'm travelling 15 miles twice a day which takes about 45 minutes each way. About 30 mins is in very slow traffic, the rest being dual carriageway. I experience the problem every day, to varying degrees :-(

 

To be honest that is not the best conditions to be driving a diesel with a DPF from what i have read, you should try to take it for a blast on the motorway at least once a week. It is unlikely that the DPF would be atempting to regen every day, you maybe just need to go for a long spirited drive somewhere to clear out any crap.

If it is still the same then I would look at the maf or the egr, some guys on here recomend unplugging the maf to see if the performance gets better. i think it is supposed to run on default settings when it is not connected.

Good luck, let use know how you get on.