Strange Power Delivery

[powerhearse]

On my C34 s2 stagea - Got the misfire problem sorted and it was great for a while, now this problem has cropped up.

I've noticed a definite decrease in power; it seems to rev just as hard and the boost gauge indicates boost but it's not accelerating properly. If anything it appears to boost more in the lower rev range than before; it feels like the boost comes on with less throttle but the power just isn't being delivered.

I've also noticed when accelerating slowly in second or third, as you increase pressure on the accelerator the revs increase from 1k to 2k, then drop back down to about 1.5k with no change to throttle position and I can hear a faint rumble/vibration. It takes an unusual amount of right foot to power through it then it seems to be normal.

Except for being considerably less powerful/smooth.

My first thoughts were leak somewhere or maybe AFM as I had to disconnect the AFM to change the pod filter back to the stock air box, maybe I dislodged something? Would unplugging the AFM cause the ECU to freak out a little?

[scotty nm35]

Unplugging the AFM can cause the AFM to freak out, perhaps try resoldering the pins on the board inside the AFM first, there is a how-to on here somewhere...

[Duncan]

what have you changed recently, what computer is it, and what boost are you running?

generally, the standard c34 computer is very intolerant of extra boost. You say it seems to be boosting more in the low range then stopping, that is typical of the car getting more air than it likes and moving to the rich/retard part of the maps which makes it quickly loose power.

[powerhearse]

Changed the pod filter back over to the stock air box, other than that I haven't changed anything...I put the pod back on the other day and had to disconnect the AFM so I thought maybe I'd freaked the computer out?

[Duncan]

unplugging the AFM should not cause an issue, unless you were very unlucky and something broke while you were doing it.

If you changed the intake I'd suspect a boost leak somewhere. Double check everything including all the clamp being tight. Also it can be hard/impossible to see if the intake is on the AFM properly so you may need to do it by feel.

[powerhearse]

Awesome, cheers for that, yeah I was thinking it might be a leak of some kind....seems to be okay now though, maybe the hose wasn't onto the AFM properly like you say?