Low boost maybe Limp Mode?

[Gti Oli]

Afternoon,

i drove my 1.8t this morning a distance of about 60 miles to university and back, on varying roads, motorways mainly. Going to uni was fine but i put £15 of petrol in at a BP on the way home and noticed towards the end of my journey that the boost pressure of my gauge had dropped from 7-8psi under full acceleration to 5. Could this be limp mode and what would cause this? i fill up from BP or sainsburys as they are supplied by BP so im hoping its unconnected to this crap petrol business.

My car is not remapped and the mods i have are minimal but i shall list them anyway in case they are causing the problem although all have been on my car for at least two months.

carbonio induction kit,
bailey recirc valve,
milltek non resonated 2.5 inch cat back exhaust
3inch downpipe.

Any ideas or suggestions to test my car further would be greatly appreciated, i want my boost back! 

[ub7rm]

If just after you've started your car and set off in first it accelerates and feels as if its about to take off but then all of a sudden feels like all boost is gone................thats limp mode - a whole heap of things can cause it like MAF, O2 sensors or coolant temp sensor (the one that feeds the ECU not the temp gauge) to name some of the most common. These won't necessarily throw your CEL light on.  To check if its the MAF, disconnect it and see if it drives more smoothly without it - this will throw a CEL though.

Best bet would be to find someone with VAG-COM to se what the probs are.

HTH

[Gti Oli]

Right ive been to the dealers and my cars has been scanned so i now have the following fault codes,

01262 - solenoid valve for charge pressure control N75 Output open

i was told that more investigation work would be needed in order to identify the problem, but it maybe due to my induction kit, which i doubt.

Any one seen this code before?

[dunkz2006]

i may be totally wrong here but the 1.8t has a few problems when a dump valve is fitted i reckon that fault code is pointing towards that is your idle a bit funny on and off? i just fitted a dubtorque recirc dumpvalve where the original bosch one goes and its made hell of a difference for little money was only £30 brand new on ebay and he is a fellow enthusiast out to help dubbers rather than make a hefty profit its not very loud but does exactly what its supposed to do and the car feels much more punchy now

[Gti Oli]

The baileys one fitted is a recirc valve and has been on my car for bout 10 months so im less inclined to thinks its that,also you mention idling funny and this also has never been a problem. Been reading bout a fair bit and looks like it could be the N75 valve, goin to visit a tuning shop who i know have worked on a few turbo dubs so il find out for sure hopefully and get a replacement.

Thanks for the input, il keep you informed of the outcome

[richandhazel]

Right ive been to the dealers and my cars has been scanned so i now have the following fault codes,

01262 - solenoid valve for charge pressure control N75 Output open

i was told that more investigation work would be needed in order to identify the problem, but it maybe due to my induction kit, which i doubt.

Any one seen this code before?

01262 is throwing up a different description to the one you have just shown. Can you give me the exact age and engine code so that I can double check?

[ub7rm]

I thought that the N75 being open was an indication that the car was in limp mode rather than being the actual problem?  ie this is how the ECU limits the boost?  A symptom certainly but not the underlying problem.