Hey guys

I just did a tubi on my 09. Something that may be different, though I don’t have enough miles on the car to tell, is that the car seems to have a yo-yo affect when accelerating somewhat hard.

The issue isn't when it's floored, it's if the throttle is maybe halfway hit, there is a weird surge that makes my foot shift on/off a teetering point that makes the car surge forward then backward. It almost seems like I'm hitting a boost peak or spool up that is a little digital and not that progressive.

I don't necessarily remember this much with the stock exhaust, but it seems more pronounced with the tubi.

My previous experience is my 135i which is very linear, and my lotus that was low torque but 250hp from 4-6K. I only have 700 miles on the car, and 40 on the new tubi, so maybe there is some ECU adjustment coming. Thanks

 

Perhaps this is the variocam changeover point at partial throttle. I have felt it before in my car.

 

I experienced the same thing when I first got mine and took it to the dealer for a checkup. The said it was most like the vario-cam because it always happened at part throttle right around 2800-3200rpm. If I hard on the throttle nothing and the same if I just eased it on. It also just seemed to happen in 1st and very rarely in 2nd.

Now I just get on it harder all the time.

 

Make sure you don't have a loose boost hose.

 

I'll check this tonight, I did have hoses off for the install.

 

That is what I recently have been experiencing?

 

Update, I set up the boost graph and I'm not getting over 5 PSI, though a lot of noise. We may have a winner!

 

+ reps all round, thanks guys.

Yeah, it was the main hose off the Y pipe. It had blown off, it must not have been seated right. Crappy a$$ mechanic! Oh wait, that was me, nevermind.

 

Just drove it with full boost through the tubi. 6K RPM sounds awesome and pulls hard!