VAG COM Logged - your thoughts and help please gents

[dazzer]

Have been getting the following recently:

17963 - Charge Pressure: Maximum Limit Exceeded
P1555 - 35-10 - - - Intermittent

Therefore I cleared the code and logged the following. I got as close to 6800 rpm before a camper van foiled my run. From the readings the MAF looks OK to me although in 3rd gear the reading drops as the RPM increases - this look strange would you agree? However should I be concerned with the boost readings? I made three runs and never got the error code!

AMD - rr=320bhp. g is the gear I was in.

......rpm.....Maf..........rpm.......S Boost.........A Boost
.........................................990-1800 mbar <=1800 mbar
g..../min.....g/s........./min...........mbar...........mbar
3....2480...11.47.......2520..........1000..............990
......2520...38.78.......2640..........1000............1030
......2720...37.72.......2800..........1000............1060
......2960...61.97.......3080..........1000............1150
......3120...36.94.......3200..........1000............1100
......3280...42.22.......3440..........1230............1100
......3600 142.25......3960...........2190...........1910
......4320 234.94......4720...........2080...........2080
......5120 261.39......5480...........1990...........1900
......5800..273.44......6160...........1920...........1850
......6440..278.42......6760...........1360...........1760
4....6080..........0......4440...........2150...........1140
......4560..244.03......4720...........2080...........2200
......4880..251.5........5000...........2050...........2000
......5200..256.58......5320...........2010...........1950
......5480..267.42......5640...........1970...........1930
......5760..269.5........5920...........1760...........1900
......5960...68.58.......5960...........1000...........1180
......5880....30...........5880..........1000...........1100
......5800....15.83......5760...........1000...........1050
......5680....17.08......5640...........1000...........1040
......5560....17.89......5520...........1000...........1040
......5640..118...........5600...........1970...........1610
......5720..274.58......5840...........1960...........1930
......5960..275.53......6080...........1940...........1880
......6200..280.92......6320...........1940...........1870
......6440..279...........6520...........1940...........1840
5....6640..284.44.......6280...........1000...........1660
......5520....10...........5040...........1000...........1090
......5000...14.25........4840..........1000...........1050

Thanks for looking and I appreciate your thoughts on these figures and any other suggestions. I am not keen on doing this often as I like having my licence. It was fun though....

Cheers
Dazzer

[SimonS4MTM]

Looks okay to me, the error code you reported is quite common i believe.

My old car did the same, i think it is either caused by an air leak, though your numbers do not show one. Or it is because of the chip, as the car is producing more boost, some spikes may appear that is above the ecu's threashold so it puts it into limp mode.

I stand to be corrected however

[gezzerS4]

I have had a similar from Mine from Time to Time, it is also AMD stage 1 @ 320 ish, it happened more just after the chip was modded, not so much now though, (although I feel I am a little power down somewhere).

I never managed to re-create the error code by doing any form of power runs though, so I am guessing that it is under certain conditions of temp, atmospheric pressure, throttle opening and road speed that sets it up, and it never went into Limp mode, so I am guessing that it must have been very momentary each time.

Boost in 3rd does look strange, although KO3's do fall off after 5000 RPM I believe, but I thought it would happen in a all gears, perhaps someone can shed some light on that one.

[dazzer]

Thanks geezers,

The only time I have experienced limp mode has been when cruising at 75-80 in sixth then plant my foot - it was just like driving an aspirated motor, zero boost, but don't know whether that was linked to the DTC. It then reset itself and all was OK.

I also sent the figures to AMD. They basically said that I may have an air leak. I find this strange as I would have expected the error code to have shown on one of my runs with that kind of boost. They also said it was not uncommon for the sensors to report inaccurate readings and to book the car in. The last point is a fair suggestion - diagnosis by e-mail is not reliable.

Thanks for replies - if I get to the bottom of it I will report back.

[dazzer]

GezzerS4,

Just noticed you are running Bailey DVs. What do you think to them?

Cheers
Dazzer

[tartan_rob]

Boost in 3rd does look strange, although KO3's do fall off after 5000 RPM I believe, but I thought it would happen in a all gears, perhaps someone can shed some light on that one.

I don't think the boost is dropping off significantly. The boost starts to drop but the ECU is starting to request less boost from the turbo's. Check out the Spec'd boost.....

[JonnyX]

Can you do a a full run in 3rd? (2k rpm to redline). It's a bit difficult to really see what is going on. Log 003 and 115.

Your MAF figures look really high, what mods do you have?

[dazzer]

I am running AMD stage 1, Miltek Cat Back, S/S. DVs are 710Ns.

Won't be able to do another run until over the Easter period. However I will give it another shot.

[Dippy]

Dazzer,

Firstly as an AmD customer myself, I do not believe that you should blame their chip. This will be a fault on your car so do not ignore it. I have only ever seen this code once myself, and it was due to limp mode caused by a faulty exhaust sensor.

I agree with Jonny, your MAF peaks are too high. That's what I get and I have the FULL Miltek system.

Also looking at your data, although actual boost lags behind demanded, your differences after lift-off look high. At one point you have 400 mbar above demanded and later it is 660 mbar! Of course since boost is falling at these points it is OK, however it might be enough for the ECU to detect and raise the DTC.

Although I am far from an expert, an air leak seems likely. Basically since the ECU has closed-loop control using the MAP sensor reading, this will introduce some hysteresis: With some air leaking the turbos have to work a little harder to maintain boost. When you lift off, this means that for a short time there is more pressure in the TBB that Audi designed for, causing the DTC.

An air leak matches your high MAF readings.

Of course you can have 'internal' air leaks with your DVs, but I can't decide in my head if this would cause a higher MAF or not. Since DVs are easy to test I recommend you check yours.

[dazzer]

Cheers Jonny/Dippy,

I have a spare new set of 710Ns so I will swap them over as a matter of precaution and give it another run and see what VAG COM throws up. To play it safe I will get it into AmD for a health check.

Hopefully I can report something conclusive at the end.

Dazzer

[dazzer]

Cheers Jonny/Dippy,

I have a spare new set of 710Ns so I will swap them over as a matter of precaution and give it another run and see what VAG COM throws up. To play it safe I will get it into AmD for a health check.

Hopefully I can report something conclusive at the end.

Dazzer

[MarkB]

Dazzer

Did you ever get to the bottom of this? My car seems to be doing the same and is similar spec...

Thanks