TFSI hesitation/missfires at high rpm's

[jon-tfsi]

I eventually got the car down to JBS for them to have a look at it. After a few hours of logs, inspections and more logs, they were pretty confident it was the n75 valve as the boost is pulsing.
I have got a new n75 to fit and had a look at doing it myself but its in an unbelievably awkward place to get at. Fingers crossed it solves the problem and it was only £16!!!!

 

[zyklon]

N75, it seems strange, but it could be.
This has changed my piece does not exist. filter for petrol, petrol pump and also KMD kit, sensor Low fuel pressure (G40) coils, spark plugs and more things, still at high rpm misfire from 4th.

The only improvement was the move settings, fuel, 9 to 3 and less failed, but failed.

Luck with the N75, if I find fault with the writing on the forum, I think more and more the fault of the electronics revo.

Greetings.

 

[jon-tfsi]

Aargh!!! This is getting frustrating. After getting the N75 valve replaced which was suggested as the offending part, the problem is still there. The most frustrating thing is there are no codes to indicate where the problem lies. Tons of logging has been done also.
As it hesitates the boost drops slightly and so does the fuel pressure. Occasionally the boost will drop right off and the dump valve will blow off under full throttle.
It only seems to do this at 5000rpm and over with the Custom Code map on. With the standard map on it doesnt do it at all, and with a more aggressive map the symptoms are worse and it happens lower down the rev range.
I have managed to eliminate the following possible causes:
MAF
INTAKE
PLUGS
COIL PACKS
PCV
DV
N75
HPFP
FUEL FILTER

If it was down to poor flow of the fuel, would it not show up as a fault on the low pressure fuel system? Also if it was poor flow presumably i wouldnt be seeing the good pressures on the high pressure side? I was thinking its possibly the in-tank fuel pump but if its a fault with this surely i would be getting a fault code?

 

[zyklon]

It seemed strange that the culprit was the N75.
Mine has changed all that and also too low the sensor that goes into the pump.

Only thing that gave some positive results, was enriched with the mixture of REVO SPS, so not to misfire in 4th, but in 5th and 6th, always at 6600.

I believe that in this case the problem is software. REVO said they know nothing and be all normal, but there are several TFSI and with the same problem.

With no software stock fails.

 

[chrisboyle999]

did you try the injector cleaner?

 

[jon-tfsi]

I put some forte fuel system cleaner through it. Would there be something better?

 

[chrisboyle999]

fuel addatives are all much of a muchness.

If it was down to poor flow of the fuel, would it not show up as a fault on the low pressure fuel system? Also if it was poor flow presumably i wouldnt be seeing the good pressures on the high pressure side? I was thinking its possibly the in-tank fuel pump but if its a fault with this surely i would be getting a fault code?

just re-reading your post above. its a common mistake lots of people make, but do not confuse pressure and flow.
a pump of any sort does not provide pressure, it only provides flow.
pressure is built as a result of resistance to flow.
as such, poor fuel flow if caused by some sort of restriction (blocked injector/s, kinked pipework, whatever) does not go hand in hand with low pressure, in fact the pressure is often greater.

but yes, youd like to think you would have some sort of fault code to give you a clue.

 

[Tfsi_Mike]

Seen alot about the N75 valve. Dont know why assumed it was a mk1 20vT thing.
What is it?

 

[chrisboyle999]

Seen alot about the N75 valve. Dont know why assumed it was a mk1 20vT thing.
What is it?

wastegate bypass regulator.

 

[Tfsi_Mike]

wastegate bypass regulator.

Thanks mate

wooooooooooosh (sound of that flying straight over my head ) lol

 

[chrisboyle999]

boost control valve (different name for the same thing)

 

[Tfsi_Mike]

boost control valve (different name for the same thing)

Aaaah ok, thanks again!

 

[D*P]

Can anyone on here read german? I've got a very interesting vw document relating to this issue! My dad and I both have this problem on our 58 k1's with remap only.

 

[Tfsi_Mike]

Can anyone on here read german? I've got a very interesting vw document relating to this issue! My dad and I both have this problem on our 58 k1's with remap only.

Email it me. im ok at gerrman. If i cant sus it it i live in paderborn germany sure someone here can

 

[D*P]

sent.

 

[Tfsi_Mike]

sent.

PM'd bugger wont let me, emailed

 

[leon_2009]

chaek the cam flower if it ok change the plugs if it ok chaek the fuel pump in tank
the last thing go to the delear and till them to make update softwere

 

[zyklon]

hello How can I get this document in German?

 

[D*P]

whats your email zyklon?

 

[zyklon]

[email protected]

thanks