I've began to notice what feels like a boost problem in my car but I can't really pinpoint it. I do have a 19% pulley with the stock bypass valve so maybe thats the problem. I just got it tuned by Jan a few months ago so I know the map is fine. But the story is, when I go WOT in 1st gear and I shift quickly into 2nd at redline (not slamming), The engine pulls decently right into 2nd but then a few hundred rpm's later, it feels like the power just shoots up like its a turbo finally hitting boost. It's almost like theres a slight power delay when i shift at high rpm. Throughout 1st the power is linear and I don't get this jump. Its only right after I shift. So I can't tell if it's the belt slipping after I shift, or the bypass valve is slow to close due to all the boost. The clutch is fine though. I tested that. Basically, I shift out of first at redline, power comes back slightly, then shoots back up a few hundred rpm later. Same happens from 2nd to 3rd. Sorry for the long post but I just want to be as clear as possible. If anyone has an idea of what this problem might be I'd greatly appreciate it. Thanks a lot

 

Do you have a boost gauge? A boost gauge would show you if your boost is dropping off from a leak and also slipping belt I would think.

 

I don't have a boost gauge. But the power difference is definitely noticeable from right after the next gear is engaged to a few hundred rpms later.

 

sounds like a belt issue to me. but get a boost gauge, it helps seriously

 

I say buy a new belt and see what happens.

 

Currently I'm using the Napa 535 belt. Would a gatorback belt be a better for me? If so, what is the part number for a 19%. Thanks a lot

 

Actually, I'm pretty sure the belt is fine. I can still see over half a hole on the tensioner. I guess it could be the bypass valve then. Is there a way to close the bypass valve temporarily so I could test the power again with it permanently closed? The car has 55,000 miles by the way.

 

I know some people were adjusting the tension on the spring instead of getting a Detroit Tuned? I can tell you that the spring on my OEM BPV was very weak in comparison to the DT BPV. The OEM valve was also not sealed all the way when closed.

 

yep ziptie

 

Do I have to remove the bv to ziptie it shut?

 

if your OEM BPV is not adjusted to close fully then zip tieing will not close that final gap. There is an adjustment screw on the bpv that controls the setting for closing fully and you have to remove the IC to get at it, i think. If you search on the "yoyo chronicles" you'll see pictures and descriptions on it. Its a huge posting though, with lots of tial and error analysis and fluff. I went through it once and wish there was just a summarized version with just the juicy details - perhaps there is but i dont know of it

 

How about having the traction control switched off?

 

You know what, I actually thought of that today so I went out and tested it with and without the dsc on. Without it on the power is linear the whole time. That seems to have fixed it then. I'll post back if it turns out to be something else. Thanks for all of your help though. Haha another pointless thread .

 

Good to hear. Your description reminded me of how annoying BMW traction control is, so I thought I might as well throw the idea out there!

 

I had so much hesitation in my car with dsc on i have it permanently switched off and instead toggle it on only when its raining. I use one of those window up + dsc off chips

 

Dont you have to be braking traction before the ASC and the DSC come into play, or are you telling me that if I turn off my ASC my car will be snappier than with it on?

 

where'd you find that, sounds llike bliss

 

details for such a auto up dsc off chip http://www.motoringfile.com/2006/01/...cuit-reviewed/

 

sounds like time for a quaife upgrade...worth its weight in gold

 

okijack nice looking car... Yeah they sure are arent they I just dont have one yet. I need some sort of LSD