Boost dip around 4000 RPM

sbrauns · 15-01-2005, 23:06

Hi all,
I have a question about my car.
When i go on WOT on the accelerator in second gear i feel a dip in torque delevery. I hooked up vag-com to plot the boost. This is wat it looks like.

The plot looks like it feels. Boost shoots up to 1.4 bar and then drops back down to 1 bar around 4000 RPM. Has anyboday else experienced this.
Can there be done anything about it? Has it to do with the settings of my tuner or would a N75 J valve fix it.
Car is chipped to around 210bhp and runs a standaard N75 valve.

Any comments.

SkodiRS · 16-01-2005, 12:18

I ran an N75J for a little to try and solve a slow spool up problem and while it did allow a slightly quicker spool up it didn't cure it entirely.

It will also give you about 0.1bar more boost so I was always hitting the limiter.

The SCN have a lot on the N75J but I think they mainly used it for standard cars and not to cure remapped issues. Check them out for more info.

Perhaps what you are seeing is you hitting the boost limit, which is 1.4 bar IIRC, and then the time taken for it to spool back to where it was. Also I guess you will also see some boost fade at the end of the range due to heat.

Just throwing some ideas around.

*all my normal disclaimers apply.

Fasterbaby · 16-01-2005, 15:10

How do you rig VAG COM up to read that? I would like to test mine to see how it looks.

sbrauns · 16-01-2005, 15:50

Use vag-com to log block 115. In here are RPM spec. boost and actual boost. the log you can than import in Excel. and make i nice graph from it.

Fasterbaby · 16-01-2005, 16:18

Thanks i'll try that with mine tomorrow and then compare it with what i get after it has been jabba'd on tuesday.

***DGW*** · 16-01-2005, 16:28

Is the chip you have tweakable (tuneable) and has your car always had the problem?

sbrauns · 16-01-2005, 16:56

No the chip is not tuneable. And since my car has been chipped it has done this.
But when you drive it you can feel it, but it isn't to bad.

What i thought is that when you hit the boost limmiter it always jumps into limp-mode and that the limiter was around 22 psi and mine just hits 20 psi.
Could it be a defective N75 valve?

Ninj · 15-06-2005, 15:22

Sorry to be a biff but how do you import those figures into Excel to plot it as a graph - Im a bit of an Excel pleb

Thanks

Richie

***ncarring*** · 15-06-2005, 15:31

VAGCom saves them as a CSV file which opens automatically in Excel anwyay. To make a chart, select the columns you want and press the chart wizard button (the one on the toolbar with a little bar graph on it). It will do most of the work for you and you can work out the rest by right-clicking on the chart it produces and playing with the options.

Ninj · 15-06-2005, 15:33

Excellent, I figured it would be a csv.

Thanks again

Rich

faboka vrs · 15-06-2005, 15:37

You have to deduct atmosphere pressure which is 1bar

***ncarring*** · 15-06-2005, 15:39

of course. I will delete my post.

15-01-2005, 23:06	#1
sbrauns Briskodian Join Date: Jun 2004 Location: Netherlands Posts: 57 Thanks: 0 Thanked 0 Times in 0 Posts	Boost dip around 4000 RPM Hi all, I have a question about my car. When i go on WOT on the accelerator in second gear i feel a dip in torque delevery. I hooked up vag-com to plot the boost. This is wat it looks like. The plot looks like it feels. Boost shoots up to 1.4 bar and then drops back down to 1 bar around 4000 RPM. Has anyboday else experienced this. Can there be done anything about it? Has it to do with the settings of my tuner or would a N75 J valve fix it. Car is chipped to around 210bhp and runs a standaard N75 valve. Any comments. __________________ Silver octavia RS 210BHP/326Nm Forge 007P

16-01-2005, 12:18	#2
SkodiRS BRISKODA Staff Join Date: Oct 2002 Location: darkest Hampshire Posts: 8,650 Thanks: 0 Thanked 17 Times in 13 Posts	I ran an N75J for a little to try and solve a slow spool up problem and while it did allow a slightly quicker spool up it didn't cure it entirely. It will also give you about 0.1bar more boost so I was always hitting the limiter. The SCN have a lot on the N75J but I think they mainly used it for standard cars and not to cure remapped issues. Check them out for more info. Perhaps what you are seeing is you hitting the boost limit, which is 1.4 bar IIRC, and then the time taken for it to spool back to where it was. Also I guess you will also see some boost fade at the end of the range due to heat. Just throwing some ideas around. *all my normal disclaimers apply. __________________ Adrian.

16-01-2005, 15:10	#3
Fasterbaby Briskodian Join Date: Oct 2004 Location: Grimsby Posts: 732 Thanks: 0 Thanked 0 Times in 0 Posts	How do you rig VAG COM up to read that? I would like to test mine to see how it looks. __________________ www.fasterbaby.co.uk www.ulcebybengals.co.uk My gallery Ex Octavia Vrs, now Volvo 850 T5 Rica'd to 304 bhp.

16-01-2005, 15:50	#4
sbrauns Briskodian Join Date: Jun 2004 Location: Netherlands Posts: 57 Thanks: 0 Thanked 0 Times in 0 Posts	Use vag-com to log block 115. In here are RPM spec. boost and actual boost. the log you can than import in Excel. and make i nice graph from it. __________________ Silver octavia RS 210BHP/326Nm Forge 007P

16-01-2005, 16:18	#5
Fasterbaby Briskodian Join Date: Oct 2004 Location: Grimsby Posts: 732 Thanks: 0 Thanked 0 Times in 0 Posts	Thanks i'll try that with mine tomorrow and then compare it with what i get after it has been jabba'd on tuesday. __________________ www.fasterbaby.co.uk www.ulcebybengals.co.uk My gallery Ex Octavia Vrs, now Volvo 850 T5 Rica'd to 304 bhp.

16-01-2005, 16:28	#6
*DGW* BRISKODA Staff Join Date: Oct 2002 Location: Cambridgeshire Posts: 17,112 Thanks: 48 Thanked 165 Times in 122 Posts	Is the chip you have tweakable (tuneable) and has your car always had the problem? __________________ Denis 2002 Octavia 1.8T 4X4 turbo Estate - rebreathed on by Jabba ... 31.93mpg 2007 Fabia vRS - CC, ESP and full leather trim by Seat Surgeons ...48.09 mpg...

16-01-2005, 16:56	#7
sbrauns Briskodian Join Date: Jun 2004 Location: Netherlands Posts: 57 Thanks: 0 Thanked 0 Times in 0 Posts	No the chip is not tuneable. And since my car has been chipped it has done this. But when you drive it you can feel it, but it isn't to bad. What i thought is that when you hit the boost limmiter it always jumps into limp-mode and that the limiter was around 22 psi and mine just hits 20 psi. Could it be a defective N75 valve? __________________ Silver octavia RS 210BHP/326Nm Forge 007P

15-06-2005, 15:22	#8
Ninj Briskodian Join Date: Jan 2004 Posts: 83 Thanks: 0 Thanked 0 Times in 0 Posts	Sorry to be a biff but how do you import those figures into Excel to plot it as a graph - Im a bit of an Excel pleb Thanks Richie

15-06-2005, 15:31	#9
*ncarring* Don't talk, drive! Join Date: Feb 2003 Location: The B roads of Britain Posts: 12,903 Thanks: 15 Thanked 87 Times in 75 Posts	VAGCom saves them as a CSV file which opens automatically in Excel anwyay. To make a chart, select the columns you want and press the chart wizard button (the one on the toolbar with a little bar graph on it). It will do most of the work for you and you can work out the rest by right-clicking on the chart it produces and playing with the options. __________________ Nick

15-06-2005, 15:33	#10
Ninj Briskodian Join Date: Jan 2004 Posts: 83 Thanks: 0 Thanked 0 Times in 0 Posts	Excellent, I figured it would be a csv. Thanks again Rich

15-06-2005, 15:37	#11
faboka vrs Briskodian Join Date: Oct 2003 Location: Merseyside Posts: 5,941 Thanks: 11 Thanked 35 Times in 35 Posts	You have to deduct atmosphere pressure which is 1bar __________________ John Take away the poor damping, inadequate bushes, heavy diesel lump and spongy brakes its not a bad warm hatch

15-06-2005, 15:39	#12
*ncarring* Don't talk, drive! Join Date: Feb 2003 Location: The B roads of Britain Posts: 12,903 Thanks: 15 Thanked 87 Times in 75 Posts	of course. I will delete my post. __________________ Nick

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