jerky acceleration

**cwrtcoed** · 01-05-2010,10:09 PM

Hi
I have been having a few problems recently with my 2005 a4 140 tdi.
On acceleration the car is jerky and missing as if its lacking fuel, if you push the throttle down slowly and gradually build up speed its not to bad, im not sure as to whats causing the problem.
When i first start the car in the morning sometimes it turns over for ages before starting, and other days its ok.
Also the dreaded esp light comes on now and then, more so in dry weather. i plugged in a diagnostic and had a code of 00526 brake light switch -F sporadic 011 open circuit, i can clear it but then may reappear again whenever it feels like.
anyone experienced any of the above and how to i fix these faults.

re
rich

**fourringsrus** · 02-05-2010,11:36 AM

Do you know when your fuel and air filters were last changed ,if the fuel filter is clogging up you may experience the 'missing' and lack of power.
In reference to the 'brake light switch' fault code,I believe this may not be related to an actual brake light switch fault,as sometimes the brake light circuit can show errors related to ecu and accompanying components.
What I have said here may not not be 100% enlightening but it's certainly worth further investigation by a top tech at Audi or a reputable specialist.
Somebody else will be reading my remarks and hopefully be able to elaborate and clarify.
Good luck

Stuart

**cwrtcoed** · 02-05-2010,06:35 PM

The car has done 63,000 miles the air filter has been changed but i dont think the fuel filter has been. Would this cause it to be hesitant /jerky acceleration? Any other advice would be appreciated

**fourringsrus** · 02-05-2010,10:14 PM

Yes absolutely,if you imagine that the air filter is to the engine ,what a smog mask might be to you and I you will see that if the engine can't breathe clean air it won't breathe and die.
As for the fuel filter, the fuel is cleaned/strained/filtered just before it gets to the engine.
If the fuel filter becomes blocked the filter will not allow a good strong ,clean supply of fuel to the engine.
So if both filters were,shall we say spent, the engine is unable to breathe and not getting fuel, much like you trying to run up a mountain on an empty stomach with a clothes line peg on your nose during an asthma attack.
I would strongly suggest a service at the soonest if you are unsure of the cars recent service history and a code scan would shed more light on your other troubles

Stuart

**cwrtcoed** · 04-05-2010,08:32 PM

i have put a code reader in but theres nothing coming up besides the esp fault. if the filter is blocked would it show up on the reader?
re
rich

**fourringsrus** · 05-05-2010,10:09 PM

I would have thought not, if the filter is clogging up you would get some thing along the lines of "insufficient fuel supply"

**Alan02** · 05-05-2010,10:15 PM

Check out the Stop lamp switch fault if it is still current.

**cwrtcoed** · 06-05-2010,07:13 PM

because no fault registered on the code reader it gave me suspicions if it was the fuel filter that was causing the problem.
Is the stop lamp switch by the brake pedal? This is strange beacuse i had the same fault on my vw golf gt tdi. Both had a tunit box fitted, would this have caused the problem or you just think it may be coincidence.