Quote:
Originally Posted by Jonny H
If I set my timing to 14 BTDC it would idle at 1500 RPM too. Surely it needs to be down at 5 degrees BTDC or less?
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Quote:
Originally Posted by '76 911S 3.0
I would try to set your warm base idle with the idle valve completely closed and use your base throttle blade position to get you your desired idle speed. From my experience with the Carrera idle valve, with the electrical connector disconnected, the valve is open about 25%. I have my base idle set using the blade base position (you can use the bleed screw to fine tune), and even with the idle valve completely unplugged, it will settle into a rock steady idle at 950 RPM every time.
Also make sure that there is no Idle Ignition PID active when setting the base idle (not sure if MS has this functionality), or any idle ignition modifier active. It sounds like there might be an Idle Ignition modifier going on in the background that, when it becomes active, starts chasing its tail and might be causing your oscillations and stalling.
And FWIW, my idle ignition timing is 10 degrees BTDC.
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Thanks guys. I just went through another cycle of trying some adjustments and logging.
I dialed the ignition back to 7.5, then 5, then back to 7.5. Not a huge change.
Once warm, I closed the throttlebody bypass all the way. Then I closed off the idle valve (Anything below 20 is closed on this idle valve, i locked it at lucky 13.) Then I backed off the throttle stop until the idle went into its usual surging up to 2000 rpm and down to 600. If I back off further it just dies. If I screw it in to 2.2% throttle it will idle smoothly there at 1500 but anything below that is just cycles between 600 and 2000.
I richened up the fuel map there too and even when its cycling the AFRs are 12 to 13.
I eliminated the idle valve by closing it, and closed off the throttle bypass almost all the way (just a 1/4 turn open so I have some downward-adjustment) and locked in the timing to 5, 7.5 and 10. I adjusted down the idle with the throttleplate screw but still I get this cycling.
Any more help? I suspected a vacuum leak but I cant find anything.