Looking for any sort of advice guys.

I had two fault codes:

17608 - Boost Pressure Control Valve (N249): Mechanical Malfunction

17563 - Manifold Abs.Pressure Sensor (G71): Circ. Short to B+

The car has been revo'd and should be 200+bhp (mods in signature) but had been running at around 150bhp. So it went in to be fixed. I had the following work done (some were general maintenance not related to the above faults):

- Clean + lube starter motor internals

- Clean throttle body

- Replace turbo charger divert air valve (N249)

- Checked wiring, connections, pipes and hoses of Manifold absolute pressure sensor (all fine)

- Auxiliary belt changed

- Forge diverter valve fitted

SWMBO picked it up and I used it to go to work last night. I plugged my liquid gauge in and it gave 4 fault codes, which I stupidly didn't write down. I decided that as the car had been worked on they could have been as a result of that and cleared the codes. I presumed that if they were genuine problems that they'd come back over the 20 mile trip to work.

I set off and it felt ok until I got to the first open road and the first chance to really go for it. I floored it in 2nd with the liquid monitoring bhp. The car accelerated. Slowly. The liquid measured a max of 116bhp!!! It felt like it to. I kept testing it and on one occasion it gave a kick and jumped to a max of 145bhp and felt like it did before it went in to have the work done but still not like it did when it was 200+bhp.

I then switched the gauge to boost pressure. Max was 410mbar which works out to about 5.9psi!! The car is definitely ill. I got to work and checked for fault codes and it came back with nothing at all.

The only two options I can think of are replacing the N75 (solenoid valve for charge pressure control) or replacing the turbo but I could really do without the cost.

It was previously running at around 150bhp with the two fault codes so I don't see why the work I've had done would make it worse.

Any ideas would be helpful. Cheers.

who did the work? Revo? as they should of test driven it afterwards and then scanned it for error codes.

No it was Revo mapped about 10k miles ago. It was a local Vag specialist that I always use.

Strange there is on fault codes running that amount of boost! is the dv ok? if you ever wanted to test the n75 i have a spare you could try. I'm not far from you.

I might actually take you up on that Martin. It's my last hope before I think I'll need a new turbo unless anyone else can suggest anything less expensive to try?

How hard are the N75s to swap?

That was one other thing. I used the liquid to check the N75 position. I was in third quite low down the rev range (Certainly less than 3k) and blipped the throttle for only a second. The car hardly reacted at all but the reading went from 0% to 95% straight away. Would that suggest that it's opening/closing to easily and would that cause my problem (I've wandered into a realm I know nothing about here so forgive me if I've just been talking complete rubbish!).

Anyway I'll leave it to the expertise of the forum for a while and come back later. I'm off to bed. (I'm on nights).

Cheers in advance again guys.

yes the n75 operation sounds fine they start high and should drop off. If you did pop round i will have a look at it with you and fit the n75 if required.

I doubt very much that it is the turbo itself at fault, as when they go, they go!

But it does sound like the wastegate valve is sticking open. This could be due to a duff wastegate valve, a duff wategate actuator, or a duff N75. First step would be to try Martins N75, then check the wiring to the N75, and the hoses from the N75. Then get under the car to try and visually inspect the wastegate actuator and rod ends (where it enters the turbine housing and where it enters the actuator) for damage or wear. You could even test the actuator, if you have a controllable pressure source and a DTI. That's how we run hysteresis checks on them.

I'm not sure how the wategate valves are attached to these turbos, but at the most I'd imagine it would need a new or rebuilt turbine housing if it is that. Forge make aftermarket actuators for the KO3 so that shouldn't mean a new turbo either (Forge Motorsport | Alloy Fabrication).

But hopefully it's just the N75!

Cheers for that guys. I'll PM you to arrange that then Martin at some point. Is it a big job swapping the N75 over? Just wondering how much time we'll need. Cheers again.

About 5 mins, need to get the original one use clips off (unless they already have jubilee clips on), swap n75 and fit some new jubilees.

Can you source three jubilee clips size 000 (9.5-12mm)?

Edited 5 March, 200917 yr by martziniuk

maybe the ecu has been flashed and is now running a standard map??? as the boost pressure is the same as a standar octy and your gettng near 150 :confused:

Its below standard boost Clive, looks more like a limp mode boost setting to me.

isnt standard boost 6 psi?? or is it 8 psi ??

just a stab in the dark really:thumbup:

Standard boost is 9-10 psi. Hopefully another n75 may help?

In relation to whether the ECU may have been flashed - It is running below standard bhp which I know can happen but it is well serviced and well looked after but the torque is 20-30 nm up on standard. So I don't think it's that but you'll know better than me.

And I'm guessing even if it was standard map then the other mods would contribute something to take it slightly above standard. Granted it's only a DV and an induction kit but still.

Cheers.

PM sent Martin

Just checked the part number of that valve Dave, it is a N249 valve which they have put in the place of where the N75 goes :eek::confused:

You will need the correct n75 to put where we put mine and to put the N249 where it should go under the inlet manifold,then we are getting somewhere.

Take it to someone who knows what they are doing.

Cheers again Martin. You've answered part of my PM anyway so ignore that bit.

Guess I'll be taking it to Bradford then! At least I know it'll be in good hands.