[Chris050999]

Hi!
Long story short, swapped my downpipe to a catless one, and now I have no power.

After the swap I went for a small drive to another garage to slap a tune on the car, and I got a "Drive malfunction, go to nearest service center". Figuring it would be related to o2 sensors or similar, i kept on driving and flashed a stage 2 OTS tune. After the flash, I still have exact same power.
Went from a 328i to feeling exactly like a 316i (~110hp) after the swap. Relevant codes: 120208 - Boost pressure regulation, pressure too low

During the swap I broke the midpipe-downpipe exhaust clamp (N20 uses regular exhaust clamp rather than the flange type i've seen on n26's. LUCKY YOU by the way, that clamp made my swap take an hour longer) and while its slightly tightened, its not fully secured and I would strongly suspect there is a small exhaust leak. Could this be the cause of my lack of power? Logs seem to show that it is still building boost fine. Bootmod3 log

Also, is this hose in the engine bay supposed to lead anywhere? Noticed earlier today that it was loose. Seems like it would fit onto the "VAC" labelled plastic connection right under it.

[BettyFkinCrocker]

Well, you are on the right track. Couple of things, that log shows major issues. You are making ZERO boost. "MAP" is the line to look at. While you are 100% throttle you are in vacuum throughout the pull. I'm not entirely sure, but that hose may control the waste gate. An alternate theory would be the direction you clocked the vband at the turbo to downpipe connection. The wastegate arm could be hitting the vband, not allowing it to close fully/properly. If neither of those seem to be the issue, maybe just try reflashing/recoding. It's unlikely to be the issue but worth a shot. Once you look into those things, contact PTF directly to see what they think.

Exhaust leaks should not cause any real loss in power, so I'd doubt that has anything to do with it.

[J3LLY]

I changed to catless downpipe with stage 1, and the CEL of the map config is OEM, nothing happend during the way I came home.
And then I took the stage2 map and set the CEL off, nothing happened too...

[Chris050999]

Originally Posted by BettyFkinCrocker

You are making ZERO boost. "MAP" is the line to look at.

Thanks, this lead to the fix.

Originally Posted by BettyFkinCrocker

An alternate theory would be the direction you clocked the vband at the turbo to downpipe connection. The wastegate arm could be hitting the vband, not allowing it to close fully/properly.

After moving the vband, I discovered that there is infact no way to install it in a matter that it would block the wastegate arm.


ISSUE IS FIXED.
The loose hose that I posted a picture of is wastegate control and obviously needs to be connected =)
There was also a second hose for the same purpose behind it.

They got disconnected without me being aware of it as the hoses lead to the plastic engine cover, which I had no issue taking off. I find it odd that such vital parts are not secured in any way, I would expect a clamp or atleast a zip-tie.

Thanks for the help lads, rookie mistake but the car now runs great at 266whp
Funfact: n20 engine without turbo and cats sound like a 6th gen honda civic.

[Gen13 F36]

Originally Posted by Chris050999

Funfact: n20 engine without turbo and cats sound like a 6th gen honda civic.

No way I owned a EK civic si with B16A. No way man... just my 2 cent.