Oorspronkelijk geplaatst door
Pierro
hier een doc die het process goed weergeeft voor wat betreft koude motor en warmloop...
The first thing to do when adjusting CIS is to do nothing to the adjustments. You need to inspect the spark plugs, plug wires, ignition timing, camshaft timing, valve clearance, and vacuum lines FIRST.
CIS adjustments are VERY STABLE, unless expendable/maintenance items or ignition adjustment need replacement or adjustment.
The worst thing you can do is to start screwing with the setting when you don't have everything else to snuff.
NEVER make adjustments to a CIS fuel system when it is cold. The system has cold start, and cold running compensation, in the form of the WUR, cold start valve, and aux air regulator. Idle speed and mizture are adjusted AFTER the engine is at normal operating temperature.
Cold Start Valve is a 5th injector that injects extra fuel when engine is cold to aid starting.
WUR lowers fuel system feedback pressure to allow the airflow sensor arm to rise higher when the engine is cold, allowing more fuel into the engine when it is cold.
Aux Air Valve opens when engine is cold to allow more air into engine when it is cold to increase idle speed.
If you have already taken care of all the maintenance items listed above, the the exhaust is now rich with the engine at normal operating temperature, the adjustments were probably fiddled with when some vaccum lines were leaking, and now after replacement, with proper vaccum restored, the mizture is rich.
The opening on the air flow sensor box needs a long 3mm hex wrench to adjust the idle mixture. Mixture is adjusted while the engine is running. DO NOT PRESS DOWN while making adjustment. Adjustment is always made from RICH TO LEAN.
The default starting adjustment position for the idle speed and idle mixture are approxiamtely 2.5 turns out (counterclock wise) from all the way in (clockwise).
Idle speed is adjusted on the throttle body (flat screwdriver).
Check and ignition timing first. Then, adjust idle speed. Now find the engine idle sweet spot (middle of the adjustment range where turning the adjustment screw does not affect idle speed) turning the adjustment to the left and right to find the ends of the adjustment range, then setting the adjustment to the middle of the range. Now, go back and recheck the ignition timing and the idle speed, and readjust to factory spec.
Go around and around until the idle speed, ignition timing, and idle mixture are all in spec.
The hole in the air flow sensor box is a leak in the vaccum system. Make sure that you plug it before taking any critical mixture readings, and after you are done adjusting the idle mixture. The earlier 924s, and VW Golf, Jetta used a rubber plug on a stick, which can also be used on the later 924
succes,
Pierro