Mk2 VRS stage 1 boost question

[octydan]

I had a stage 1 generic map put on to my 2008 tfsi a few weeks ago. (71k miles, pipercross panel and no other mods.) sometimes it feels really quick and other times just adequate. I've carried out a few logs on the Torque App. It appears that I'm getting a peak boost pressure of 21 psi, quickly  dropping to around 15 to 17 this fluctuates depending on which gear I'm in. Does this sound right? I also seem to have an issue where once I start the car for the first time in the morning and immediately drive it it feels like it's holding back (almost like the brakes are being held on) then it suddenly goes, holds back maybe once or twice more and then it's fine for the rest of the day. Any ideas.? Thanks in advance. 

Edited 31 March, 2018 by octydan

[MarkyG82]

I don't know much about remapping in particular but a mechy so some experience with engine stuff.

Most engines whether turbo or not have a sweet spot in the accel where if you give it too much it'll big down a bit so back off and it'll give it some more. Could be related.

As for the not being full power first thing, do maps have smarts built in to limit power when first started as they go through 'calibration' to get the best for the current conditions? Would make sense to me.

Boost pressure will also drop off, as the faster the engine turns the more air it'll use. Only way to increase the boost at higher revs is to bolt on a bigger turbo.

Sounds like your map is optimised for max boost as soon as possible. Might find it drives nicer with the boost backed off a little.

[octydan]

Thanks for your reply Markyg82, what you say makes sense with regards to the max boost level coming on soon as possible and also the bogging down. When you say "back off and it'll  give it some more" do you mean back off the throttle and reapply it? Also the flat spot issue first thing in the morning seems like more than a calibration, as the car seems to barely accelerate even with a small amount of throttle. At this same time the exhaust strangely appears louder... This only happens for max 30 seconds driving though then it feels like you've been driving with the handbrake on and just released it. 

[Mr G 76]

Here's a log of my Shark stage 1, it peaks at about 19.5 PSI, then progressively drops until it's producing around 11 PSI at the redline

[octydan]

Nice one. Thanks for posting that.I did some logging on torque app but I think I need to redo it in 3rd or 4th gear to get a more accurate reading and then plot it on a graph as you have . Are you pleased with the shark map? Looks quite smooth.  Also is a standard tfsi about 10 psi max? 

[MarkyG82]

When I say 'backoff' i mean ease off. Should find a spot in the pedal travel where more power is found. This then moves as the engine spools up. Kinda like in the old carb days when giving too much throttle would make it far too rich a mixture and wouldn't give max power for the fuel.

Does that make sense? V tired and brain not right today 

[octydan]

Haha. Yes that makes sense. I will give that a go. Cheers. 

[Mr G 76]

10 hours ago, octydan said:

Nice one. Thanks for posting that.I did some logging on torque app but I think I need to redo it in 3rd or 4th gear to get a more accurate reading and then plot it on a graph as you have . Are you pleased with the shark map? Looks quite smooth.  Also is a standard tfsi about 10 psi max? 

 

Yeah the map's really smooth and very similar in its delivery to stock.

 

My boost plot was done in 3rd. 4th to the redline is too fast for my preferred 'test road'.

I believe standard boost pressure peaks at around 11 PSI. This'll vary from car to car especially as even the newest TFSI's are 9 years old now!