924Board.org

kcoyle · Joined: 15 Jan 2011 Posts: 712 Location: Long Island, NY

Sooooo,

I adjusted the throttle stop and "timing" as per smoothie's excellent instruction. I can get the '"o" timing mark to align in the timing window but that leaves me at around 725 rpm's which is pretty low.
Putting the air temp sensor back in doesn't seem to have any effect.(not sure if it really should at idle should) I also went back and checked that my A/F mixture was good according to my dwellmeter and the reading was around 45 which I believe is spot on.
Air temp sensor is at 5k at room temp(around 70 degrees)

How does one get the idle higher properly?

KC
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1982 931- Stock with MBC at 8psi

Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.

emoore924 · Joined: 13 Apr 2004 Posts: 2822

There should be a procedure in haynes. IIRC, if all else is well (timing, fuel pressure, blah), you introduce an air leak into the TB with an adjusting screw. More leak = higher idle. But everything else needs to be right first or you're just compensating for a problem elsewhere...

kcoyle · Joined: 15 Jan 2011 Posts: 712 Location: Long Island, NY

Yea, my copy of the FSM is missing a few key pages, like the next page after this one.

_________________
1982 931- Stock with MBC at 8psi

Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.

Nein37 · Joined: 29 Dec 2009 Posts: 513 Location: New London, CT

You need to unplug the oxygen sensor connector on the cross member. With it plugged in your frequency valve is always working to adjust mixture to stoich, so your mixture is probably off a bit causing the low idle.
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1981 931 CGT replica, OEM CGT intercooler, .8 BAR WG spring, GTS Headlights, Innovative Wide band A/F, A/C delete, 16" Fuchs, Weltmeister 200lb lowering springs, Bilstein HDs front, Koni Sport rears.

kcoyle · Joined: 15 Jan 2011 Posts: 712 Location: Long Island, NY

I will try that tonight. Also, found the full page below in my pile of electronic paperwork.

I will adjust mix with 02 unplugged and try again.
thanks!

_________________
1982 931- Stock with MBC at 8psi

Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.

kcoyle · Joined: 15 Jan 2011 Posts: 712 Location: Long Island, NY

Well, after starting over from scratch (again) it appears I have successfully followed a set of instructions. We be idling smoothly at around 850. Still seems low to me but what do I know.
Thanks all!
_________________
1982 931- Stock with MBC at 8psi

Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.

tyfighter123 · Joined: 19 Jan 2010 Posts: 551 Location: Colorado

Now come do it to mine!

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Porsche 924 1977 N/A
Mustang GT/CS 2007
Porsche 924S 1987 (parts car)(cut up and recycled)
Porsche 911S 1976
Porsche 931 1980
Porsche 931 1980 (parts car)

kcoyle · Joined: 15 Jan 2011 Posts: 712 Location: Long Island, NY

No problem, I'll be over in 5 min.

_________________
1982 931- Stock with MBC at 8psi

Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.

musicalannette · Joined: 21 Feb 2012 Posts: 413 Location: UK

That ignition system looks interesting, I presume it is all closed loop without any real maps, does the system have a knock sensor?
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

kcoyle · Joined: 15 Jan 2011 Posts: 712 Location: Long Island, NY

Don't know, it's over my head. Here's some detailed reading for ya.

http://photobucket.com/ditc1
_________________
1982 931- Stock with MBC at 8psi

Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.