2004 A4 1.9tdi occasional loss of power on motorway [Archive] - Audi Forums

: 2004 A4 1.9tdi occasional loss of power on motorway


viz
03-07-2012, 06:52 AM
Hi

I am new here and hope someone can offer some help. My A4 is the 1.9 tdi 130bhp B6 model (2004) with engine code AVF.

When I take my A4 on the motorway occasionally there is a complete loss of power, the car drives as if there is no turbo and really struggles to pick up especially up hill.

Then at the end of the journey when I stop the engine and restart it, it drives fine. There are no error codes displayed either during or after the loss of power.

Any advice would be greatly appreciated.

mullardel34
03-07-2012, 08:37 AM
Hmmm... start with the simplest possible answer; the problem could be crappy fuel. Bad/contaminated diesel fuel has sidelined quite few Audi TDI vehicles, so only fill-up with "Top Tier" rated fuels (Top Tier Gasoline (http://www.toptiergas.com/retailers.html)) for the next couple of refuelings (at least half of a tank at each refueling) and see if the problem is resolved.

Next up the diagnostic chain would be to replace the fuel filter; this simple act has corrected for quite a few power-loss problems which were intermittent enough not to leave behind any diagnostic fault-codes. If the fuel filter on your Audi has never been replaced, then it's at least an 8-year-old unit and is certainly due for replacement.

Keep in mind that there are a number of fault conditions which are logged in the ECU, but don't necessarily result in the illumination of the "check engine" light (the dreaded, "lightning-bolt to the engine-block" icon.... ;-)

So have the ECU scanned for any stored diagnostic fault-codes. If you don't have a VAG.COM diagnostic scanner, most of the major US auto-parts stores will download and list any stored diagnostic fault-codes for free with a generic OBD-II code-scanner. Interpreting the engine fault-codes is something of a "black art"; you have to consider all observed symptoms as well as all reported fault-codes and correlate this information in order to arrive at a rational prognosis.

Good luck! :cool: