It's embarrassing. I was neck and neck with an old LDV van on the motorway the other day. This can't continue! (2000 Golf Tdi AGR) My car is going in to (according to extensive googling) 'limp mode' when any stress is put on the engine. So around town the car is fine, but as soon as; - I go over 65* - Accelerate hard - Drive up inclines ...it goes in to limp mode and is very very slow. If I turn the ignition off and on again it resets itself. The first thing I did was replace the MAF but that didn't solve it. That was easy to do but anything more technical is stumping me really. What should I try next? Would it end up being big bucks to send it to a garage? Due to being skint as usual I'm thinking I'll have to try and fix it myself
It could The vanes in the turbo will be sticking My tdi has done this a few times once I'v freed off the vanes is fine
I've just found this thread, http://www.audi-sport.net/vb/a4-s4-forum-b5-chassis/107121-un-sticking-your-tdi-vnt-turbo-vanes.html Sounds like something I could do, and it's cheap. Just need to get my head round it lol
Do you have a VVTurbo? is the 1st question,I know its a comon problem with hem but its best to check 1st lol. The 2nd one is,have you checked for any fault codes? my guess is;its a boost "threshold breach" or "overboost" removing the intercooler and flushing it out with petrol would cure part of that (make sure you remove all the petrol or it could cause more problems than you fix) Get the codes read 1st though.
If it's a non PD engine it may not have a vnt turbo some do some don't If it don't check all the vac hoses also the n75 valve can play up as well putting it in to limp mode My TDI always under boost's It is worth scanning for fault codes but both the above can show the same fault
I think it's non PD, I'm not sure how to check if it's got a VNT turbo? I'm going to change the vacuum lines first then because it's the cheapest, has anyone got any links to a guide?
It's an agr so its not pd, it also has a wastegate (the only mk4 tdi with a wastegate) i.e. not vnt. I know this because I have had the same problem for the past 2 years and im fed up at this stage, i changed the n75, cleaned the egr and inlet and replaced air flow meter and nothing has solved it. I'm now confident its my turbo but its not vnt so what do I have to do to try and free it up from sticking?? Regards - Jamie
Basicaly your ecu is reading boost pressure outside what is expecting to see based on the boost reference maps. Your map sensor lives inside the ecu and reads boost. If the line to it (probebly a material/rubber braided line) has split, the ecu will see less boost than the airflow meter is seeing being drawn in. I would also suggest checking all vac and boost lines, for oil ingress aswell as splits. Really you need someone with vcds, as it should be apparent straight away if a sensor is at fault. A diagnostic will also stop you wasteing time and money on replaceing stuff that isnt at fault.
Scanning will always reveal a huge number of issues!! Another way of just testing the turbo vanes can be applying vacumm on the pipe that goes down to it. looking down you should see the arm moving if you get a long screw driver on it you shouldn't be able to push it further if all is well. as dubnutter says also check all the lines and you getting suction on when your on idle, a faulty valve will also loose all the amount of control the n75 has to play with
