Please Help

[inarush]

Hi all, I have just bought my first Galaxy a w reg tdi. On the drive home the car went in to the famouse limp mode. I got the car cheap so was not that bothered as i have a good knowledge of cars,, or so i thought lol. I bought a vag scanner and plugged it in and the code that came up were 17958 (p1550) charge pressure deviation. and 17563 manifold pressure sensor short to b+ positive, what the hell does that mean b+ positive? The car is hard to start when warm ie= 10 seconds but starts first time when cold. I have also noticed when its hard to start i some times get a single beep, sounds like its coming from the key area, Have i bought a wrong un or is this common. I think the p..ck i bought it off has tried to have a go at it as there is tale tale signs. Many thanks in advance. Oh and by the way i think its a 110 hp

[seatkid]

17952 / P1550 - Charge Pressure: Control Deviation - Control Limit Not Reached - Intermittent

 

If its a 110bhp (AFN) engine, it is fitted with a variable vane geometry turbo. Although it could be a number of things (mainly to do with the vacuum controlled boost circuit), your first port of call should probably be to check the vane actuator mechanism on the turbo, this is known to get sticky in old age due to a build of carbon deposits etc. Check it moves freely, there are several threads on the forums about how to do check this and suggested methods of freeing.

While your at it, check all the vacuum piping (and there is lots) for leaks/splits etc. The main vacuum line going from the brake servo to the vacuum pump is a stiff plastic affair that often splits in old age nears any connection. The smaller vacuum pipes perishes with age.

 

17563 manifold pressure sensor short to b+ positive

means the output signal from the sensor has hit the upper limit and could indicate an electrical short of the output to the b+ wire. However, I think the pressure sensor for your car lives in the ECU behind the dash so its more likely a side effect of the turbo boost fault. Reset the code with the VAG scanner first and see if it returns.

 

The AFN engine has a known history of problem starting when hot. Various reasons have been sited, a tired battery or low charge (poorly alternator or burnt out fuse box in engine bay) (which might be the reason for the beep) is common, a knackered starter motor (brush gear) is another possible reason - apparently the AFN engine requires a minimum cranking speed to start. An air leak at the fuel filter T piece is another possibilty - usually because the O ring that should be fitted has been lost or has been damaged/not replaced when the filter was changed.

Edited March 24, 2012 by seatkid

[inarush]

First off i would like to thank you for your reply. have been out and had a quick look at the vacum pipes and blimey your right there is loads. i will change them all for new rather than check them for cracks. I think its probably best to take the turbo off and inspect it for seizure as it a tight squeeze around the back of engine, One thing though i dont understand if the fuse box has commited suicide would the hard start fault be there all the time. As i have said i think the last owner had problems as there is bits of pipe and a spare n75 valve and maf sensor in the back, i just hope he hasnt put vac pipes on wrong. Will keep you all posted with results. thanks

[seatkid]

One thing though i dont understand if the fuse box has commited suicide would the hard start fault be there all the time.

The usual problem with the engine bay power distribution fusebox is a bad crimp on the main cable from the alternator. This crimp overheats and oxidises and melts the fuse box. The bad connection invariably leads to low or no charging of the battery. The beep you sometimes hear is probably due to low battery voltage (the ECU complaining) - low voltage whilst cranking can also mean the fuel stop solenoid valve located on the distributor pump doesnt open....

 

Your battery may just be old and tired.

 

The AFN engine (and IIRC some early PD engines) seem to have software in the ecu that looks for a minimum cranking speed before starting (I may be wrong here). Often a tired starter motor is to blame - they say the brushes get worn and some segments of the commutator dont make good contact and it spins slower.

 

The T piece on the fuel filter is a thermostatic valve, air leaks here give starting problems (cold and hot IIRC) and you can usually see air in the clear pipe going to the distributor pump. Note some small air bubbles are often seen on healthy cars and are not a problem.

[inarush]

Once again thank you so much for your reply what you have told me so far is new to me and im in your debt for it, Bad news at my end end though i had my arm broke training yesterday so was not able to to do much, Did buy a new battery wich has made no difference to warm/hot starting but cant do much in the way of vac pipe change. Something i forgot to mention though is i get turbo chatter or flutter on changing gear wich after reading through previouse threads sounds like bad news= pending on your age. The younger generation seem to want it, must make there man bits bigger, i dunno. I will keep you informed of what i can do over the next week or so you never know my efforts might help some one somewhere. once again thanks seatkid, you are already a legend.

[mrben]

Hello seat kid, great posts btw. I' v just taken off my fuel filter to drain and replace. Where abouts should the o-ring be on the t piece please? i didn't see one (although i'm not having any problems). Would a new filter come with the o ring? thanks.