00544 Fault Code RS2

[Lloyd]

I'm trying to solve an intermittent boost problem with the RS2.
Not sure if anyone else has had this problem?

The only fault code given (aside from usual 00513) is:
00544 - Maximum Boost Pressure Exceeded, 35-10 Intermittent.

Occasionally, when the car touches 2.1 (maybe even 2.2 bar on overboost), boost is quickly and smoothly cut right back for 1 or 2 seconds and then returns in full as per normal right away. It's not a hard cut, it's really smooth. Car then drives as per normal. I can't get it to repeat the fault/boost cut. It just happens every now and again. I think it's most frequent with overboost.

I've checked the hoses for the N75. All good.
I've pulled out, cleaned and checked resitance of the N75. All good.
Car has fairly new silicon boost and vacuum hoses throughout.
99% of the time, car runs perfectly to it's usual max 1.9 bar boost.

Would be grateful to hear thoughts on what I should check next?
At the weekend I will carry out a full boost leak test with soap and update the thread.

Cheers

[Rusty]

Sounds similar to what Sonic and Ross were saying at ADI. No solution was mentioned, only soft boost cut.

[UrS4boy]

S2 3B and ABY and RS2 ADU Boost Leak Testing

...The only fault code given (aside from usual 00513) is:
00544 - Maximum Boost Pressure Exceeded, 35-10 Intermittent....
Would be grateful to hear thoughts on what I should check next?
At the weekend I will carry out a full boost leak test with soap and update the thread. Cheers

There is a bit more to the 00544 code defintion that probably makes sense:

•2224 (Blink Fault Code), 00544 VAG1551/2 Fault Code Number
Maximum Charge Pressure Exceeded,
Intake air leak after turbocharger, ECU Vacuum/pressure line has leak between intake manifold
Waste gate or pressure hose, Waste Gate Solenoid/hose problem, ECU pressure sensor malfunction
Symptom: Misfire during wide open throttle, boost pressure too high

Definitely sounds like you should start with the boost test.

Here are some hints on that:

http://www.s2forum.com/forum/showthread.php?t=63974&highlight=boost+leak+testing

[UrS4boy]

Just to highlight this:

"Many people, most notably prj (dmitri) have suggested that the simplest method of boost leak testing that captures all the possibilities in one go is to place the pressure bung in "A1" in the diagram and disconnect the hose from the cam cover to "A3" and plug "A3", leaving the rest alone. This falls some where between test Option 1 and Option 3."

[Lloyd]

Thanks for the link and input. Dmitri suggested I also check the MFTS. Anyone know how I am supposed to check/test it? Thanks.

[Rusty]

Unplug it or check if the warning line is shorted to ground.

[Ross]

I had this, very intermittently, on the RS2 before i pulled it apart last year. It is still an issue too - i had one such cut on track at ADI.

I have also noticed it always happens in 3rd gear, the boost is pretty steady in 4th + peaking at 2.1-2.2bar on the gauge. I believe i have 2.1bar requested on the midrange with a 2.3bar limit. I have noted it hits 2.3 when it cuts, it seems to go to 2.1-2.2 and creep slighly over and then cut.

Boost leak is possible, i havent tested but it was tight for the longest time. It does seem like boost ramps up and cant quite stop building quick enough in 3rd.

[UrS4boy]

F76 Multifunction Temperature Switch (MFTS) R&R Info

Thanks for the link and input. Dmitri suggested I also check the MFTS. Anyone know how I am supposed to check/test it? Thanks.

Some F76 Multifunction Temperature Switch info here (be aware that the connector might crumble when you remove it):

http://forums.quattroworld.com/s4s6/msgs/22584.phtml

[Colesy]

I have a similar issue to this also. It only happens at WOT on full boost to begin with, after it's done it once it will keep doing it until an ECU reset. The boost cuts for ~1 second and then comes straight back on. I've fully boost leak tested and there are no leaks...

So would be very interested in finding out a possible cure for this as well. I'll pull the codes again and see if I have the same as this.

[prj]

Interesting...

If you guys want, I can increase the boost cut threshold in your software, but that's not really fixing the issue of why the boost goes too high in the first place.

The thing is, it's not an instant cut - for it to kick in, you must be overboosting 200+ mbar over a period of some time. This should never happen normally.

[Lloyd]

I had this, very intermittently, on the RS2 before i pulled it apart last year. It is still an issue too - i had one such cut on track at ADI.

I have also noticed it always happens in 3rd gear, the boost is pretty steady in 4th + peaking at 2.1-2.2bar on the gauge. I believe i have 2.1bar requested on the midrange with a 2.3bar limit. I have noted it hits 2.3 when it cuts, it seems to go to 2.1-2.2 and creep slighly over and then cut.

Boost leak is possible, i havent tested but it was tight for the longest time. It does seem like boost ramps up and cant quite stop building quick enough in 3rd.

I will have another look to see if it's the same with my car....

What could cause it to over boost ? I would have thought that a boost leak would have had the opposite effect...

[prj]

Boost leak can actually cause described behaviour if it is a slight leak.
The ECU is adaptive, and so if it it can't reach setpoint, then it might overcompensate in some other cases.

Could be a problem with the N75 being really old ... could be wastegate playing up...

[Lloyd]

I checked the N75, clicks ok and resistance is within range. Also cleaned it right up.

Will also check the diaphragm on wg

[Ross]

Could be a problem with the N75 being really old ... could be wastegate playing up...

I was thinking this.. tried to get it to cut coming home from work but it behaved impeccably. Is having a 1bar spring going to make it less 'accurate' on boost control? Certainly when it boost cuts it is very quick to drop to a controlled 1.1bar and then back up again which makes me think it's not.

What peak boost are you running Lloyd/Colesy? Wondering if our old WGFV's don't like high boost as much? Or the stock WG perhaps? Just seems like it only happens where boost builds very quickly and peaks >2bar. An extra 0.1bar would be a quick fix, if I'm not going to break anything that could be a good band-aid but I'm in no rush. Perhaps when I go RS4 MAF I might try a replacement MFTS some time.

[prj]

You can try to reduce the spring tension slightly, that might also just be enough to fix the issue.
And yes, you are right, it is harder to control boost with a stiff spring... Most aftermarket tunes I have seen have boost cut completely disabled, but I don't really like this approach