I have a problem with turbo boost "chocking" after an upshift - any advice would be highly appreciated!

I recently installed Autothority Mass Air Flow kit in my 1989 944 Turbo. My track car is otherwise stock, except for Fabspeed 2.5" exhaust with no cat converter. It now pulls much stronger, and if I floor it, the boost gauge swings to 2 bar and we really go flying, while waste gate is hissing. I upshift just above 6,000 rpm, hear the blow-off valve dumping excess pressure, but then the car looses power - it feels "stuck" at 4,000rpm and does not respond to throttle. I have to ease off and then it gradually rebuilds the boost. This nose-diving "flutter" is a nuisance on the street and will be a real problem at Lime Rock, where I am heading for DE. If anyone had a similar problem, please share your thoughts and advice.

Andrey

 

What wastegate are you using? You know that the boost guage on the dash measures vaccum up to 1 bar and then anything over that is boost. I am assuming you are referring to that guage and not actually running 29 psi on your car?

BTW - Congrats on your first post on rennlist! You should add the general area of the country you are in and post up some pics of your ride!

 

I would look at the diverter valve. It may not be working properly.

 

That was my first thought as well.^^^^

 

Thank you for your quick replies and advice. Yes, I refer to the dash gauge - otherwise the engine would be blown up by now. As I don't have the catr converter and this is a differential gauge, the actual boost is more than 1bar - 1.2-1.3 perhaps. The waste gate is stock and the diverter valve same (is it the same as a blow-off valve?). I will take a look into the valve idea - any suggestions on the replacement or stock is good, just needs a check? Any other changes that are advizable wth the Autothority - Tial wastegate, boost controller, etc.?

Andrey

 

The diverter valve is very similar to a Blow Off Valve except it recirculates air. Look around. Forge is very popular one. I would not get stock. They blow up in about 6 months. They still use a rubber diaphragm so get something with a spring or piston. Like the forge.

http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT

This looks like a good knockoff piece which I am thinking about buying myself.