00544 Fault Code RS2

[Sonic]

I had similar with mine... tried another WG and same, so i assumed it wasn't the WG. After lots of faffing i opened up the new one and it was seized. Finally replaced it with a brand new TiAL, and not had the problem since.

This was seperate to the boost issues i was having after gear-change, which were as a result of the hall sensor being every so slightly out.

[prj]

Yup, just to re-iterate, the cut is programmed into the ECU and is a safety feature to prevent engine damage.

The cause for the cut is the boost pressure exceeding the setpoint by more than 200mbar (usually what I set it to) for more than a second.

Why it is exceeding it - could be a crappy mapping job on my part, could be a hardware problem. If the car did not do it while mapping and for extended periods of time, and then just suddenly started doing it, then it is usually something hardware related.
As said - I can up the cut threshold, but it's just a band-aid, it's not solving the underlying issue.

[Lloyd]

I went out in the car today and filmed the boost gauge and tacho whilst driving WOT in several gears. Today I was able to repeatedly get the boost cut problem in 3rd and 4th gears. It seems to be cut most frequently when going WOT from low RPM like 2k-2.5k rpm. I was seeing max overboost at 2.1 bar gauge and it was dropping to 0.9 bar for about a second before coming back on as per normal. Normal max boost is 1.9bar with my tune.

The car certainly was not doing this when we mapped it and only started doing this back in April AFAIK. Hasn't been driven much since as I've been busy elsewhere. Will do the boost leak test and see what that offers. Will then try a 1/4 turn back off the WG spring.

[Lloyd]

OK some good news.

Wound the wg spring right off, to 1/4 +ve and ran the car. Boost cut gone.
Gradually, increased the spring compression and testedt with WOT pulls.

So far, I'm back to 3 +ve turns on and still no boost cut.
I reckon it was roughly set to about 4 +ve turns before testing.

I wonder if the wg piston had somehow siezed up a bit? By winding the spring compression right off and doing a few WOT pulls it's now freed right up.

[Ross]

Hi Lloyd

That is good news. Sounds like the spring being too tight was indeed the problem. I'll have to wind mine out a bit, its at 1.1bar so pretty high. I noted yours was cutting about 1bar too, any chance of a quick pull with the WGFV unplugged to see what its at now?

[Rusty]

Stock spring? Stock spring has 10mm of pre-load when measuring the depth of the standard allen head screw from the WG upper surface. This equates to 0.4 Bar at WG crack, dropping to about 0.3 Bar at redline.

If it's not stock then just ignore the above

[Lloyd]

@ Ross, sure will have a look next time.
@ Rusty, I think it's 1.9 bar spring

[prj]

Just to update here - Colesy's was a fuel cut, and it seems it was caused by bad MAF connector, as it's sorted after cleaning.

[UrS4boy]

@ Ross, sure will have a look next time.
@ Rusty, I think it's 1.9 bar spring

Sorry but if you had mentioned that it was a 1.9 Bar spring in your original post, I probably would have suggested that the perch is wound in too far. I had a nasty cyclic boost cut on WOT, say in 3rd gear, when I first installed a 1.9 Bar WG spring in my RS2'd UrS4. The solution was to wind the perch up until the boost cut went away.

My theory was the 1.9 Bar WG spring resultrd in a rapid rate of rise in boost pressures that was outside the "understanding" (map) of the ECU and it "freaked out" for a moment, cutting boost via the WGFV. When the boost dropped, the rapid rise started again and again the ECU would again panic and cut boost. This would go on (over a few seconds) until I got my foot out of it. Taking spring pressure off the WG was the cure.

[Lloyd]

Yes, winding off fixed the problem. Weird thing is why should it have started doing this in the first place? Spring tension has not been adjusted since mapping.

[prj]

Sorry but if you had mentioned that it was a 1.9 Bar spring in your original post, I probably would have suggested that the perch is wound in too far. I had a nasty cyclic boost cut on WOT, say in 3rd gear, when I first installed a 1.9 Bar WG spring in my RS2'd UrS4. The solution was to wind the perch up until the boost cut went away.

My theory was the 1.9 Bar WG spring resultrd in a rapid rate of rise in boost pressures that was outside the "understanding" (map) of the ECU and it "freaked out" for a moment, cutting boost via the WGFV. When the boost dropped, the rapid rise started again and again the ECU would again panic and cut boost. This would go on (over a few seconds) until I got my foot out of it. Taking spring pressure off the WG was the cure.

Thing is it was mapped with the spring like this.

Yes, winding off fixed the problem. Weird thing is why should it have started doing this in the first place? Spring tension has not been adjusted since mapping.

Which gets me to this... no idea. But at least it's cured now.

[UrS4boy]

Thing is it was mapped with the spring like this.

That is curious/wierd.

In my case, the chipset is a "generic" AAN MRC Stage 3 (RS2+) 3 Bar/K24-7200 chipset so probably not the 1.9 Bar spring.

[Ross]

You'd normally expect a spring to weaken over time... Perhaps being a stiffer spring causes it to bind or catch as things wear over time. It doesn't seem to be an uncommon side effect of a 0.9bar spring.

Incidentally mine hasn't cut since castle coombe now! I'm sure it will tomorrow now I've mentioned it... that said I hardly ever seem to get to open her out in 3rd gear, too much town driving.

Obviously I had no issues under mapping either, although I did find the ECU line pinched which seemed to cause overboosting quite frequently for a little while afterwards - it became infrequent after a little while, I guess the ECU learns a bit?

[prj]

The ECU does adapt the pilot map for the N75 somewhat, yes.

[Ross]

So I tempted fate.. 3rd gear pull and after a second or 2 at 2.3bar it boost cut.

Loosened up the wastegate screw and wound off 1.5 turns, took it back out for a spin, a touch smoother coming on boost (less aggressive) but WOT in 3rd gear and it's up to 2.1bar and holding steady. No overboost and no cut