Miata Turbo Forum - Boost cars, acquire cats.

Miata Turbo Forum - Boost cars, acquire cats. (https://www.miataturbo.net/)
-   DIY Turbo Discussion (https://www.miataturbo.net/diy-turbo-discussion-14/)
-   -   Freeway speeds, VTA, and 02Clamp (https://www.miataturbo.net/diy-turbo-discussion-14/freeway-speeds-vta-02clamp-6149/)

Braineack 12-13-2006 12:58 PM

I never had a bucking problem VTA, only an engine cutting out problem.

jayc72 12-13-2006 01:02 PM

Maybe what you call cutting out and what we call bucking are the same thing?

Splitime 12-13-2006 01:16 PM

Get rid of the AFM? ;)

Braineack 12-13-2006 01:46 PM


Originally Posted by jayc72 (Post 64295)
Maybe what you call cutting out and what we call bucking are the same thing?


no. i mean 0rpms are hard to mistake.

jayc72 12-13-2006 02:11 PM


Originally Posted by braineack (Post 64310)
no. i mean 0rpms are hard to mistake.

Ok, your car is busted.

Braineack 12-13-2006 02:28 PM

no, it's why a huge vacuum leak on a metered engine sucks.

SamS 12-13-2006 02:41 PM

...literally :gay:

getsidewaysd1 12-13-2006 06:22 PM

Lol

samnavy 12-17-2006 05:45 PM

O2 Clamp Installed!
 
Well, I just went for a nice little jaunt to test out the O2 clamp just installed. My freeway cruising jerkiness seems to be about 50% gone. At 75-80 though, I'm still in that grey area where a breath on the pedal takes me from -10vaccum to 8psi in an eyeblink. I honestly think that the turbo is spooling and making positive pressure while the manifold is still in vaccum and the boost is just going straight out VTA. I can hear the turbo wind up and can modulate the gas to keep the BOV open. I can hear both working at the same time... my record is about 6seconds, during which time, the car will jerk like crazy (but a lot less now due to the 02Clamp).

Olderguy's instructions say don't adjust the little brass screw on the clamp unless I've got a voltmeter. Can I adjust it a little bit pretty please if I mark where it was when I started just to expiriment? If so, what am I looking for in response. Is moving that little brass screw going to do something I can feel.
Also, it comes set to "clamp" at .5psi... any reason I should want it to wait until more boost to clamp.
What should I be trying to feel wrt driveability to "tune" the thing... or is most of it stuff to mess with on the dyno?

olderguy 12-17-2006 05:54 PM

You can increase the boost pressure setting by turning in the allen screw on top of the switch clockwise. I run mine about 1-1.5psi so that I don't hit clamp at high speed cruise.

Changing the voltage to the ECU during clamping should be done with a digital voltmeter. It is set to send a pretty lean signal. Counterclockwise will make the signal more rich, but it is very sensitive.

bripab007 12-17-2006 08:57 PM

Yeah, I can guarantee you're turbo's producing boost at freeway speeds and spitting the excess out the bypass valve. I can clearly hear my bypass valve venting on the freeway...it's built into the compressor housing (recirculating) and it makes quite a bit of noise at those speeds.


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