Cruising Boost Surge

Oatmeal

Discovered I just like symmetrical AWD
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Well, I probably know the answer already but was hoping for a 2nd opinion.

B7 A4 1.8T Quattro SE. It's been remapped from the standard 163 -> ~210.
Got a Forge 007 with a green spring. Intercooler has been replaced with a large fmic (just an eBay job but it'll do for this power).
Manual Boost Controller in parallel with n75, boost gauge, etc (just to limit boost to 15psi, was otherwise jumping to ~20psi in the mid-range)

So the issue I'm seeing is when I'm cruising at 70mph, come a bit of an incline, the boost will slowly build as the load increases to ~5psi, then it surges up to ~8psi. Then drops to 3-4psi, rinse and repeat.
It's quite annoying to be happily cruising up a hill and the car jumps on the boost then drops off over and over, like once every 2 seconds.

In an ideal world, regardless of the lag, the boost would be based on how much power I was demanding from the engine with the throttle over the whole range of travel. What I find is that the first 30% of pedal travel is all vacuum, 30-40% is the first 5psi, then 40%-42% is 8psi+, followed by 42%+ which seems to just pin the thing to near full boost until you push the pedal to the floor.

It's great that it spools quickly but the power delivery is very challenging to deal with with such a small gap in throttle position meaning the difference between pushing on and aggressively flooring it.

I have checked and the setup for the N75 + MBC is correct. They work together.

Is this just a map issue? Like the tune is just too aggressive with wanting to build boost or is there some mechanical aspect of this that needs looking at?
 
If you ask me the map you got right now is purely based on performance... and not nicely done either, take it to a reputable remapper that makes the car daily driveable yet still can get the maximum performance out AKA take it somewhere for a custom map done on a RR. (rolling road)
 
Funnily enough, it wasn't the map. I went to Bill @ Badger5 and he is very reputable.

However, I did resolve it. So I've answered my own question but not in the way I was expecting. :whistle2:

I replaced the TIP with one from Evolution Raceworks, thankfully the B6 variant fits the B7 very nicely.

I also replaced the crankcase breather elbow as mine had completely fallen to bits, absolute nightmare, spent the best part of 2 hours with an endoscope and a modified vacuum to get all the plastic junk out.

Swapped some of the harder to reach check valves for good measure whilst I already had the car in bits. Replaced some of those 'orrid factory clamps for jubilee clips on some of the hoses.

Fired it up and it's a completely different car! Feels brand new, everything is so smooth now. Boost response is near instant and I can more easily control the boost pressure with the throttle.

The only thing to note was that after installing the TIP I used some cheap silicone hose from the N75 to the TIP. This kinked and my boost wouldn't get much past 9psi. Replaced this with a reinforced hose and now it's back to the usual 17psi.

Still got a weird boost dropping issue with WOT at like 5k+ in 3rd/4th but I'm taking it back to Bill to investigate this.
 
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could be that the exhaust is a bottle neck if you are still running the oem diameter from turbo back.