NeS4atu

<center><img src="http://pictureposter.audiworld.com/29650/boost-graph.jpg"></center><p>Been having some problems with uneven power when I go into a WOT condition. So I decided to do a log of Block 115 showing actual versus requested boost, then graphed it. You can clearly feel the rise and fall and rise in acceleration that the graph shows. By 4440 rpm everything smooths out. Pedal was floored the entire run. Any ideas what could be causing this? Here is the data for those with better charting:

2320-6000 RPM WOT 3RD GEAR
Time, Engine Speed, Engine Load, Specified Boost, Actual Boost
14.83,2320,105.2,2170,1220
15.13,2440,123.3,2120,1400
15.43,2560,147.3,2080,1650
15.73,2720,176.6,2050,1950
16.04,2880,191.7,2070,2280
16.35,3080,179.6,2100,2380
16.65,3240,167.6,2120,1980
16.95,3440,184.2,2160,2100
17.25,3600,191.7,2200,2230
17.54,3760,191.7,2210,2290
17.85,3920,189.4,2280,2230
18.16,4120,184.9,2300,2160
18.47,4280,188.7,2270,2230
18.78,4440,186.4,2250,2240
19.10,4640,184.9,2220,2230
19.42,4800,181.9,2190,2200
19.76,5000,177.4,2160,2150
20.09,5160,173.6,2130,2110
20.45,5320,169.1,2080,2070
20.80,5520,165.4,2050,2050
21.15,5680,160.9,2020,2030
21.50,5840,155.6,1990,1990
21.87,6000,154.1,1940,1970

VR_Life

Post turbo hose, clamp or TBB that is leaking under pressure ... done yer pressure test ?

Bramell-EVOvert

The requested boost looks to be osolating. Why not use lemmiwinks to turn down the wastegate duty cycle, then use a bleeder to bring the pressure back up to where the software expects it?

At 100% duty it will cause some irratic requests. However, the requested could look funky simply because of a boost leak, and the active n75 control. I would need to see more charts like this on healthy cars to know for sure.

PSmalls::DoggieStyle

Check for leaks. If you can't find one, do a log of block 003 under the same driving conditions.

NeS4atu

<center><img src="http://pictureposter.audiworld.com/29650/boost-graph2.jpg"></center><p>Same test later in day after turning the N75 1/8th turn. Granted this wasn't back to back testing. But look at the lag on initial WOT and the overall lower boost values for much of the run. I will say tho that on the second run the power 'felt' much smoother and more sustained. Strange tho why the initial requested boost was higher than before after tweaking the N75.

NeS4atu

Is there a way to log 2 different blocks simultaneously with ProDiag? (block 003 timing + block 115)

Bramell-EVOvert

Yeah, put a bleeder in there to raise the boost back up.

PSmalls::DoggieStyle

You can log more than one block at a time, but you get less readings/sec. I recommend you either get APR ECU Explorer to log tons of variables at once or you log one block at a time with VAG-Com.

PSmalls::DoggieStyle

I'm not a big advocate of messing with the N75.....BTDT.

NeS4atu

and going to look again for a leak - Maybe a parallel MBC will help. Can someone explain tho how a boost leak can cause a boost spike?