Help noob buying an Audi a4 avant

[Tobiasnugent]

Hey I'm looking at buying a T reg Audi a4 avant 2.5 tdi. It has a problem were when you accelerate to say 75mph the coil light comes on and the engine cuts out but if you turn the ignition on and off while your still mOving it works again. Also takes a while for the coil light to go out when starting

Is this a common fault ? Also does anyone have an engine bay picture of the 2.5 it appears to have some sort of filter that doesn't look like it should be there with four or so pipes going into it at the top of the bay near the windscreen.

Any help would be appreciated

 

[murran]

that filter will be the fuel filter. by your description, that sounds like the place it should be.

the coil light flashing indicates and engine fault. youd need to have it code read.

 

[Tobiasnugent]

The issue is the light only comes on when you go to that speed and doesnt stay on. Would they still be able to read the code ?

 

[tdia4]

Yeah it will be logged in the ecu, so will be there untill you clear the code.

 

[Tobiasnugent]

Okay cheers do you think it could be serious ? Sorry for all the questions I'm more of a Honda man myself

 

[nwmlarge]

sounds like a boost solenoid issue which may be affecting fuelling hence the light only coming on at a certain load.
the only way to find out is to have it read.
stick a few 20's in your pocket and go chat up a mechanic

 

[adamss24]

Boost solenoid wont trigger the coil light on the dash but will put the car in limp mode. Me money will be on a VP44 injector pump on its last legs... I would do a diagnostic scan with vag-com/VCDS fully registered and check the dynamic timing while at it. If the timing is within spec then the pump quantity adjuster is funked and thus the coil popping on dash as the pump cannot meet the required fuel demand of 6 hungry pistons. Either way you're looking at up to 1 grand if the pump needs a rebuild !

 

[Tobiasnugent]

iv managed to get hold of a vag-com cable is there any recomended software to check ? Would the pump on its last legs show any other signs apart from just what i have said above ?

 

[adamss24]

Sometimes if the case pressure is very low then it will trigger a few faults but ussualy its a gradual power and performance loss and the pump could give-up the gost at any time(the electronic part of it). Mechanically the VP44 pumps are pretty reliable but coasting for long periods of time or dirty fuel does them no good. I would download the VCDS lite from ross tech website and scan the engine for faults. Are your brake lights working fine ? The brake switch also trips the coil light if faulty...

 

[Tobiasnugent]

Sometimes if the case pressure is very low then it will trigger a few faults but ussualy its a gradual power and performance loss and the pump could give-up the gost at any time(the electronic part of it). Mechanically the VP44 pumps are pretty reliable but coasting for long periods of time or dirty fuel does them no good. I would download the VCDS lite from ross tech website and scan the engine for faults. Are your brake lights working fine ? The brake switch also trips the coil light if faulty...

That wouldnt make the engien cut out/feel like its missed a beat would it though ?

 

[adamss24]

Will do mate, the same could be if you have a plugged fuel filter or blocked cat, the car will feel like not having enough fuel and can miss and splutter. How much money you're thinking to spend ? I might have a mechanically mint 98 a4 tdi quattro sport with a tweaked chassys and engine for sale soon- i am sorting out me "new"allroad at the moment...Pm me for more details and i could email a few pictures as well...

 

[Tobiasnugent]

This is exactly what the add says

when the car gets to over 75mph, or sometimes when your just driving about, the 'Heater Coil' light flashes on the dash. (The same light that you wait to go out when starting any diesel engine from cold). Also, when this light flashes the engine seems to miss or it seems like there is not enough fuel getting to the engine. Sometimes if you take it steady driving it goes away and sometimes it may cut out. Either way if you turn the ignition off then back on again it fixes it and car is straight back to normal. It will be fine then for the rest of your journey, or not, depending on how it feels! I'm not mechanically minded and for the reasons listed below I do not want to pay to get it looked at.