a3

[CraigLamont1]

audi a3 2007 2.0 TDI Quattro 170

hi on a cold start up the car is idling rough i put my foot on the accelerator and it struggles to get to 3k revs won’t go past that for a few seconds then i do it again and it’s back to normal there is also lot of white smoke until the engine is warm then it goes away been told it’s a few things i have a video of it but don’t know how to upload


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[Crasher]

The BMN engine, bloody awful things. Are the DPF and EGR systems still there and working? If a code read shows no faults, check the fuel filter for engine oil contamination, if there are no codes and no contamination then the usual reason for poor running is failed injectors and these cost more than the car is worth to replace correctly.

[CraigLamont1]

The BMN engine, bloody awful things. Are the DPF and EGR systems still there and working? If a code read shows no faults, check the fuel filter for engine oil contamination, if there are no codes and no contamination then the usual reason for poor running is failed injectors and these cost more than the car is worth to replace correctly.

yeah both are there took the egr valve and throttle body off and cleaned it was lots of black hardened oil the dpf was cleaned out used a dpf foam loads of smoke came out after that but the next morning it was doing the same i have a multi meter can i check the switch using that?


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[Crasher]

Switch? Cleaning a blocked DPF like that is useless, you need to know what the soot and ash loading values are stored in the ECU; if the measured load is over 40% the DPF needs removing and specialist cleaning and then a forced regeneration after a new DPF pressure sensor has been fitted and calibrated. On this engine a multimeter is about as much use as an adjustable spanner, you MUST start off buy fooling proper diagnostic protocol.

[CraigLamont1]

Switch? Cleaning a blocked DPF like that is useless, you need to know what the soot and ash loading values are stored in the ECU; if the measured load is over 40% the DPF needs removing and specialist cleaning and then a forced regeneration after a new DPF pressure sensor has been fitted and calibrated. On this engine a multimeter is about as much use as an adjustable spanner, you MUST start off buy fooling proper diagnostic protocol.

ok no problem if there is oil in the fuel filter what does that mean? il get it booked in for a check


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[Crasher]

The fuel is taken from the tank by an electric pump and sent to the fuel filter and then onto the “tandem pump” on the end of the head. This generates a vacuum for the brake servo and vacuum control system on one side and the other takes the fuel and pressurises it to around 7 Bar for the injectors. This pump is lubricated by engine oil and the seals fail allowing the oil into the fuel return system which goes back to the fuel filter and then back to the tank if tandem pump demand is too low so eventually the fuel system becomes contaminated with engine oil which will make the fuel impossible to burn off the completely and this clogs the DPF to the point the engine cannot exhale. If the fuel filter is full of black fuel then the tandem pump needs replacing and the fuel system purging and a new fuel filter fitted, the DPF will also need cleaning and then when the car has had a couple of tanks of clean fuel it will be back to normal. If the fuel filter is clean and there are no relevant codes stored on the ECU then in addition to still having the DPF cleaned, the fuel return line to the filter needs checking for air bubble using a clear section of line.

[CraigLamont1]

The fuel is taken from the tank by an electric pump and sent to the fuel filter and then onto the “tandem pump” on the end of the head. This generates a vacuum for the brake servo and vacuum control system on one side and the other takes the fuel and pressurises it to around 7 Bar for the injectors. This pump is lubricated by engine oil and the seals fail allowing the oil into the fuel return system which goes back to the fuel filter and then back to the tank if tandem pump demand is too low so eventually the fuel system becomes contaminated with engine oil which will make the fuel impossible to burn off the completely and this clogs the DPF to the point the engine cannot exhale. If the fuel filter is full of black fuel then the tandem pump needs replacing and the fuel system purging and a new fuel filter fitted, the DPF will also need cleaning and then when the car has had a couple of tanks of clean fuel it will be back to normal. If the fuel filter is clean and there are no relevant codes stored on the ECU then in addition to still having the DPF cleaned, the fuel return line to the filter needs checking for air bubble using a clear section of line.

ok i don’t know it’s my dad who fixes my car il pass it along to him later today if there is fuel in the filter could that pump be causing it? and why that smell and smoke is there because the engine can’t breath properly il update you later once he checks it


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[CraigLamont1]

The fuel is taken from the tank by an electric pump and sent to the fuel filter and then onto the “tandem pump” on the end of the head. This generates a vacuum for the brake servo and vacuum control system on one side and the other takes the fuel and pressurises it to around 7 Bar for the injectors. This pump is lubricated by engine oil and the seals fail allowing the oil into the fuel return system which goes back to the fuel filter and then back to the tank if tandem pump demand is too low so eventually the fuel system becomes contaminated with engine oil which will make the fuel impossible to burn off the completely and this clogs the DPF to the point the engine cannot exhale. If the fuel filter is full of black fuel then the tandem pump needs replacing and the fuel system purging and a new fuel filter fitted, the DPF will also need cleaning and then when the car has had a couple of tanks of clean fuel it will be back to normal. If the fuel filter is clean and there are no relevant codes stored on the ECU then in addition to still having the DPF cleaned, the fuel return line to the filter needs checking for air bubble using a clear section of line.

took the fuel filter out pics attached and some fuel from the housing and it looks like dirt but am
no expert that pic is attached



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[Crasher]

I would like to see some full from the tank, cycle the ignition a few times and the lift pump will deliver

[CraigLamont1]

I would like to see some full from the tank, cycle the ignition a few times and the lift pump will deliver

ok i had not long stoped driving when i done it is it in the filter bit cheers


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