Pelican Parts Forums

Pelican Parts Forums (http://forums.pelicanparts.com/)
-   Porsche 911 Technical Forum (http://forums.pelicanparts.com/porsche-911-technical-forum/)
-   -   MFI Throttle Body Correlation (http://forums.pelicanparts.com/porsche-911-technical-forum/501913-mfi-throttle-body-correlation.html)

BSNMOE 09-28-2009 04:22 AM

MFI Throttle Body Correlation
 
It appears that Lee Rice says to adjust throttle stop bolts out 3/4 turns, air screws out 2 to 2 1/2 turns. Then adjust air flow by turning throttle stop bolts. I assume he wants equal air flow via throttle stop bolts, leaving the air screws alone. Others, including Grady Clay say to keep the throttle bodies at stop and adjust air flow via air screws. Also, my car is a 2.4 S, and if I adjust it the Lee Rice way, should I only turn the air screws out 1 1/2 turns out as the Bosch Manual states.

tobluforu 09-28-2009 07:17 AM

I just did this on my 72 and I turned out the air screws 2.5 turns. Since my car already ran good, I then adjusted the T.B. stops until I had the stacks even, flow wise. You will then have to adjust the rods, connect them back up, drive the car around, and then adjust the air screws at 3000 rpm, rods off. If your stacks are original like mine, then it's almost impossible to get the car to run perfect. Make sure you tighten all the nuts that hold the stacks to the butterflies and the butterflies to the head as I could not believe how loose mine were.

304065 09-28-2009 07:45 AM

The 2,0 and 2,2 vs. 2,4 stacks are different-- follow the instructions in CHECK MEASURE ADJUST. One is five half-turns, the other three.

If you can't set the correlation with the air screws you're unlikely to get it right with the throttle stops.

BSNMOE 09-28-2009 04:41 PM

John, I turned my air screws out 1 1/2 turns then adjusted throttle stop bolts to get the car to idle at 950 RPM at 180 deg. This is similar to what tobuforu did however, he set his air screws at 2 1/2 turns. Because my air screws are only 1 1/2 turns out my throttle bolts have to be turned out more than Lee Rice's 3/4 turns out in order to achieve this idle. I believe this is why when oil temp is around 210 deg. my idle is around 1100 RPM. AFR around 12.8 to 13.1 and the car runs great, however all this does not answer my origional question.

BK911 09-28-2009 06:16 PM

Adjusting the TB stops or the air bypass screws both do the same thing, bypass air around the throttle bodies. How much you do either depends on your idle. If 1.5 turns gives you the right idle, than stop there.

Personally I use Grady's method. I start with the TBs closed and turn the adjuster until the TBs are still closed, but resting on the screws. Then I adjust the air bypass screws to give equal air flow across the cylinders and the idle I want.


All times are GMT -8. The time now is 01:49 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2025 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website


DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.