Fault code 17608 Boost Pressure Control Valve

[Coless3]

Hi all,

Does this fault code mean I need to replace the n249 valve or is it my forge008 needing a service? Anyone got any other ideas?

Cheers Coless3

 

[<tuffty/>]

Have you got an N249 bypass?

<tuffty/>

 

[Coless3]

No I haven't. Am I right in thinking that the n249 valve dumps the boost or not?
Is it best to do a bypass? Won't it mean that the fault code is there continually if the n249 is bypassed or am I wrong

coless3

 

[<tuffty/>]

That fault code is the result of the ECU trying to use the N249 to operate the dump valve under boost as there is an issue somewhere (typically an over boost deviation)... if the ECU doesn't see the boost pressure drop quickly enough (or at all) then this code is thrown as it implies there is an issue with the dump valve...

If you have not done an N249 bypass then it suggests the DV is the problem.. I would look at that in the first instance...

<tuffty/>

 

[Coless3]

What's the reason for a n249 bypass? I have a forge 008 fitted, should I service it? Could this solve the problem?

 

[<tuffty/>]

N249 bypass is more suited to highly tuned setups... big turbo power etc... it also serves to clean up the engine bay if thats what you wish to do.. for stage 1/2 levels of tune it is not really thats required to be done but it does improve DV response a little...

Its a protection system that is used by the ECU to prevent engine damage from an overboost situation...

I couldn't say for sure if servicing the 008 will 'fix' your problem as the very fact that this has come up in the first place is because of another potential issue requiring the ECU to try and dump boost... service the DV anyway as they do require this from time to time, make sure that its actually working too... if you are getting a fluttering sound (choo, choo, choo noise) when you lift off the throttle (even revving the engine whilst stood still will highlight this) then the DV is not working properly so check it and the way its plumbed in

<tuffty/>

 

[Coless3]

Cheers for that, I know this is properly a silly question and there properly is an endless amount of things it could be but what would make the ECU try to dump boost?

 

[<tuffty/>]

...as I explained above... too high a boost deviation... if actual boost is higher than requested boost by 200mbar or more for a set amount of time then it will try and dump boost and throttle cut to protect the engine...

<tuffty/>

 

[Gizmo20VT]

Error codes and logs would point you in the right direction , could be anything from a small boost/vac leak, to a faulty electronic component.

 

[Coless3]

Gizmo20vt

what would I be looking for in the logs? Would this highlight where the problem is coming from?
is there set values for what certain things should be running at whilst looking at a log?

 

[<tuffty/>]

You need to log block 115 as a minimum... this will give you requested boost vs actual boost

<tuffty/>

 

[Coless3]

So if my actual boost is higher then then the requested boost what would I be looking at then?

 

[<tuffty/>]

So if my actual boost is higher then then the requested boost what sort of log block would I need to do then?

If this is the case then you have a mechanical problem....

One issue at a time though... fix the DV issue then start logging...

<tuffty/>

 

[Coless3]

Have taken out the DV and serviced it and checked it is working as far as i can. Did a log block 115 and as far as i can tell the actual boost pressure and desired boost pressure are all within 200mbar.
Results were at 5760rpm ;- Actual boost pressure was 2190mbar and desired boost pressure was 2180mbar.
Could the problem just be a faulty N249 valve? Is there any way of testing it?

 

[<tuffty/>]

Not particularly...

I assume the code hasn't come back and the car is running ok? if so I would not worry too much about it at this time... if you are sure the boost is ok (what gear did you do the logging in?) then I would wait and see if you get the code again

<tuffty/>

 

[Coless3]

3rd gear ? does that boost pressure sound about right?

 

[<tuffty/>]

Would need to see the logs tbh...

<tuffty/>

 

[Coless3]

i haven't got them with me atm, would you mind looking at them tomo night.

 

[<tuffty/>]

Sure...

<tuffty/>

 

[Aaron S3 8L]

Sure...

<tuffty/>

Is there a post I can look at to help or show me how to delete it please as mines faulty changed DV and still dumping boost

 

[Stuart B]

N249 Delete is highlighted in the FAQs it takes away all that jungle of pipes and you replace it with one tube from inlet manifold to DV (and leave the electric valve connected) it was the first thing I did on my S3 after plugs and oil - ands actually pretty neat - there is another purpose for this setup that it is supposed to hold the boost pressure in between 1st and 2nd gear.

be prepared when you do this modification that you will probably break the dipstick holder and break the plastic cover in front of the inlet manifold, and if it easily undoes then someone else must have already been under your manifold?

 

[Aaron S3 8L]

N249 Delete is highlighted in the FAQs it takes away all that jungle of pipes and you replace it with one tube from inlet manifold to DV (and leave the electric valve connected) it was the first thing I did on my S3 after plugs and oil - ands actually pretty neat - there is another purpose for this setup that it is supposed to hold the boost pressure in between 1st and 2nd gear.

be prepared when you do this modification that you will probably break the dipstick holder and break the plastic cover in front of the inlet manifold, and if it easily undoes then someone else must have already been under your manifold?

Is it as simple as the only pipe to put in place is from DV to underside of inlet mani? Also it had the cover of Infront inlet recently as I did all the breather pipes that run behind it all

 

[Aaron S3 8L]

In just looked at the thread aswel... I already have my fpr going to that nipple under the inlet mani is there 2 or something or is it not rigged up correct from FPR

 

[Stuart B]

Your N249 pipe will already go under there somewhere, if I remember rightly it is on the left side of the inlet manifold if looking from the front.

You can obviously take a short cut and simply join the pipe going from the Inlet to N249 directly onto the DV (there is only one) - but you will need to extend that existing pipe and risk additional leaks.

 

[Aaron S3 8L]

Your N249 pipe will already go under there somewhere, if I remember rightly it is on the left side of the inlet manifold if looking from the front.

You can obviously take a short cut and simply join the pipe going from the Inlet to N249 directly onto the DV (there is only one) - but you will need to extend that existing pipe and risk additional leaks.

All sorted took me under and hour to take the whole lot off and do it cars boosting lovely now and DV sounds loads better! Thanks for all yours and everyone else's help