Excessively High Idle - '79 928
#1
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Hi all,
I have been getting this estate sale 928 back together (https://rennlist.com/forums/928-foru...-79-928-a.html) and after a bit of a break to put the 86.5 back together, I am back to it.
The current issue is the idle. I have checked high and low for vacuum leaks and don't see any at all. I've had the metering plate and throttle body out, replaced the injectors and the intake gaskets but no sign of a leak
If I close the idle screw all the way the car will start and idle at about 1300 RPM when it's cold. As the air slide closes up, I have to open the idle screw way up to keep it running. At that point I think I could drive it around and it would behave normally. However, if I start it up with the idle screw in that position when it's cold, It starts at like 2500 rpm.
could this be an air slide that's letting too much air through it when "open" ?
here's the unit fresh out of the freezer:
![](http://castledb.me/images/2023/08/15/IMG_2906.md.jpg)
I have been getting this estate sale 928 back together (https://rennlist.com/forums/928-foru...-79-928-a.html) and after a bit of a break to put the 86.5 back together, I am back to it.
The current issue is the idle. I have checked high and low for vacuum leaks and don't see any at all. I've had the metering plate and throttle body out, replaced the injectors and the intake gaskets but no sign of a leak
If I close the idle screw all the way the car will start and idle at about 1300 RPM when it's cold. As the air slide closes up, I have to open the idle screw way up to keep it running. At that point I think I could drive it around and it would behave normally. However, if I start it up with the idle screw in that position when it's cold, It starts at like 2500 rpm.
could this be an air slide that's letting too much air through it when "open" ?
here's the unit fresh out of the freezer:
![](http://castledb.me/images/2023/08/15/IMG_2906.md.jpg)
#2
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Just thinking through this again, I think the issue is the difference in the amount of air coming through. if it's closing off completely, that would be a problem too. I can adjust the idle for the valve open or closed, just not both
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grillage (08-16-2023)
#4
RL Community Team
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There are 2 different versions of the Auxiliary Air Valve, but I don't remember which goes with which fueling system. The other has a notch in the middle of the plate.
K-Jet is made up of a number of components and if any one of them isn't right people mess things up by trying to compensate for that by adjusting other things which may help to mask the issue but usually results in the system having an issue at another time.
Fuel Distributor, WUR, AAV, mixture screw, cold start injector, and thermo switch all need to be set correctly or good.
K-Jet is made up of a number of components and if any one of them isn't right people mess things up by trying to compensate for that by adjusting other things which may help to mask the issue but usually results in the system having an issue at another time.
Fuel Distributor, WUR, AAV, mixture screw, cold start injector, and thermo switch all need to be set correctly or good.