Limp mode

[Izzy1]

Hi Guys,

Bit of a problem. Car has been cutting out on me lately when driving at speeds of 70mph on the motorway. managed to get a fault code and googled it. came up as a MAF. replaced the MAF last night with a Bosch one and this morning it did the same thing. car went into limp mode 4 times on the way to work. is there anything else that could be causing the car to limp?

Cheers

 

[aragorn]

Whats the fault code?

 

[Izzy1]

Didn't write it down i'm affraid.
what are the other factors to consider when the car goes into limp mode?

 

[aragorn]

It could be overboosting, which might be a faulty N75 or dodgy vacuum pipework, or a faulty boost sensor making the engine THINK its overboosting?

 

[Izzy1]

what is an N75 valve? where can this be located? I'll have a look at lunch to see if i can see any damaged/loose pipes.

 

[Izzy1]

where can i locate the Boost sensor?
tried looking at the pipes at lunch but i didn't have the tools to take the cover off so will see if i can try at home tonight.

 

[aragorn]

Boost sensor is in or near the intercooler. No idea where the N75 is on a TDi.

 

[Izzy1]

i'll have a look in the engine bay tomorrow after work and see if i can find anything. will also try and get the fault code again.

 

[Izzy1]

didn't get anytime last night to check for a code will defo to it tonight. just a quick question. when i put on the new MAF will i need to reset the code in order for it to work properly?

 

[Izzy1]

this is the fault i'm getting.
17965 - charge preassure control: positive deviation.
P1557 -35-10 - - - intermittent
any ideas???

 

[aragorn]

as above.

That code means your overboosting.

Possibilities are the N75, the boost sensor itself, or perhaps sticking vanes in the turbo if its a VGT model.

 

[Izzy1]

i've looked for the N75 valve and can't seem to find it. any ideas on where is could be? what does it lead off?

i've checked the pipes and nothing seems to be leaking/damaged or loose. i've tried a new MAF and it's still giving me the fault so i'm going to take that out now.

 

[Izzy1]

located n75 valve. where can i get replacement from?

 

[Izzy1]

can anyone point me in the right direction of where to get a replacement N75 valve?

 

[aragorn]

Its a dealer only part mate. Bout 45-50quid.

Bit of an expense when you cant be sure it will fix it!

 

[Izzy1]

******. guess i'll have to try that avenue now that i know the maf isn't at fault.

just hope it fixes the problem. cheers buddy. will keep you updated on how i get on once i replace the valve

 

[timmayaudi]

I had the same problem recently, my A4 kept cutting out at around 70mph. it turned out to be a split in one of the vaccum pipes located front left of the engine in front of the air filter.. I also changed the MAF and air filter (which was full of sh*t) as they hadn't been changed and have had no problems since. i got the MAF from Euro car Parts.

my car also sounded louder when boosting which was also a give away that there was a leak. Does yours sound louder?

 

[Izzy1]

i've checked the pipes and they seen in tact. engine noise doesn't get louder. how often do the N75 valves go faulty?

 

[Izzy1]

Went to see a couple VW/audi specialist on the weekend and told them my problem. they both told me it could be my turbo and the viens might be sticking...
how do i take off the turbo and check/clean?
is there anything i need to look out for?

 

[Broken Byzan]

I would google Innotec they do a chemical cleaning kit for the VVT turbos that has a very high rate of success and doent require the turbo to be removed.

N75, Stealer or specialist only.

 

[Izzy1]

cheers mark,
any ideas on the price for this kit?
I'm hopefully taking it down to my local VW/audi guy to check it out for me. will see what he has to say before trying the cleaning kit.

 

[moschino]

Izzy,

You could try the following contact if you don't mind using 2nd hand spares.
I have obtained a N75 valve + Boost sensor from them, all OK.
Make sure you give them as much info as you can about the part so they send you the correct one.

Overton Dismantlers
Overton Garage Ltd
off Dyce Drive
Aberdeen
Scotland AB21 0EQ
Tel: 00.44.1224.722354
Parts Fax: 00.44.1224.775451
General Fax:00.44.1224.722457
Email : sales@overtongarage.co.uk

Regards,

Jim.

 

[Izzy1]

Cheers Jim,
i'm going to try and give it to my mechanic and see if you can clean out the viens this week. kinda tight for time as i'm off to climb ben nevis on the weekend. looks like i'll be taking the VW for that trip.