Understanding Actual vs Requsted boost

[__B3NNY__]

Im still quite a newbie to vag com, ive basicly got the jest of some of the other blocks, but im still a little unsure on 115. Ive posted a recent log of my car so if anybody would care to explain on whats good and bad and what you should really be looking out for. I notice that it meets boost up until around the 4.5k mark and then doesnt seem to meet boost again? is this normal or does it not matter becasue its only a fraction from requsted?


Just a general explanation of requsted vs actual would be great using my logs.


Cheers

'115				Group B:
RPM	Load	Absolute Pres.	Absolute Pres.	
				TIME
 /min	%	 mbar	 mbar	STAMP
2760	144.4	2200	1850	
2920	177.4	2200	2320	
3040	191.7	2200	2520	
3120	191.7	2200	2520	
3240	184.2	2200	2430	
3320	181.2	2190	2400	
3400	182.7	2180	2380	
3520	178.9	2180	2350	
3640	175.9	2180	2320	
3720	176.7	2190	2310	
3840	175.9	2190	2270	
3960	175.9	2190	2250	
4040	172.9	2190	2230
4160	172.9	2190	2220
4240	171.4	2180	2210
4320	169.9	2180	2190
4400	169.2	2170	2170
4520	169.2	2170	2160
4560	170.7	2160	2160
4680	168.4	2170	2140
4760	169.2	2160	2120
4840	168.4	2160	2120
4880	168.4	2160	2120
4960	167.7	2150	2100
5040	166.9	2130	2080
5120	166.2	2110	2090
5160	163.9	2110	2090
5240	163.9	2100	2090
5280	162.4	2090	2070
5360	160.2	2080	2070
5400	157.9	2080	2040
5480	157.1	2070	2060
5480	155.6	2060	2040
5560	155.6	2050	2040
5640	154.1	2050	2020
5680	153.4	2040	2020
5680	153.4	2020	2010
5760	152.6	2010	2000
5800	151.9	2020	2000
5800	151.9	2010	1980
5880	151.1	2010	1970
5920	150.4	2000	1980
5920	150.4	1990	1970
6000	149.6	1990	1950
6040	148.9	1990	1950
6040	148.9	1980	1940
6040	147.4	1980	1950
6080	147.4	1980	1930
6120	146.6	1960	1930
6120	146.6	1950	1930
6160	145.9	1950	1940
6880	41.4	1000	2250
5680	124.1	1990	1360

 

[longman]

The best way to see what is happening is to do a graph of RPM against the two boost data sets.

I have done a quick one of yours (I was bored)!!

The specifed boost value will always start higher than acutal as it requests boost to match demand (Your right foot!)

The there will be a delay before actual meets specified, thats just the turbo spooling up.

Its also common that it will over boost past the specified and then settle. Yours looks good as it follows the specified really well with no major differences.

Althought the numbers look as though they are not matching, they never will that accurately. This is nothing to worry about unless they are more than 1-2 PSI different through the range.

Thats my view anyway......

 

[__B3NNY__]

Cheers for that, The graph kinda makes it abit more easy to understand.

How did you go about making the graph?

 

[longman]

If you go on here: http://www.ross-tech.com/vag-com/cars/index.html

And download the "Block 115 Spreadsheet". You then paste the values in and adjust the scale etc to suit your values.

I have just changed it about a bit and coloured it differently to match the other ones I use.