Any 924 experts out there ?
09-22-2009, 04:36 PM
#3
Three Wheelin'
Thread Starter
Ok Car is an 81 924... Problem is ...
The car idles fine but lacks power when gas is given unless someone stands at the motor and lifts up the small plate under the fuel distributor. What could be bad ?
The car idles fine but lacks power when gas is given unless someone stands at the motor and lifts up the small plate under the fuel distributor. What could be bad ?
09-22-2009, 04:44 PM
#4
09-22-2009, 05:03 PM
#7
Burning Brakes
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The plate under the fuel distributor should be rised/lowered as the airflow changes; this is the "mechanical" control of the fuel mixture. If the airflow isn't lifing the plate as it should, that means there's too much resistance on the control plunger. Resistance is provided by a combination of fuel pressure and a spring. Opening force is provided with airflow and a counterweight.
I'd start by checking the fuel pressure regulator.
I'd start by checking the fuel pressure regulator.
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09-22-2009, 05:50 PM
#8
a set of fuel pressure gauges are an absolute necessity when trying to diagnose CIS issues. I had similar symptoms on a CIS 928. You can't guess the system. Figure out the system pressure, control pressure, and residual pressure. Then measure fuel flow. Post those numbers to the 924 board and ask for advice.
my guess is control pressure or a clogged fuel distributor.
my guess is control pressure or a clogged fuel distributor.
09-22-2009, 06:00 PM
#9
whoops... I forgot something simple. Check for vacuum leaks first. If there is a leak behind the plate there won't be enough air pressure to lift the plate and your mixture will be off.
Last edited by jdgunn; 09-22-2009 at 06:02 PM. Reason: clarification
09-22-2009, 09:27 PM
#12
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I have a 928 with CIS and it sat too long and the fuel distributor gummed up inside. It would idle fine but as I gave it gas it would start to stumble. It turned out that the plunger inside the center of the fuel distributor which hovers inside rather than be connected was hanging up on sticky gas and not allowing the fuel mixture to adjust in sync with the air plate. After alot of diagnosing, all it took was spraying a can of carb cleaner through the top and out the bottom of the fuel distributor and it ran perfect.
09-22-2009, 11:14 PM
#13
Three Wheelin'
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Make sure its not binding at all. The fact that you can raise it by hand
and it revs tells me that the plunger itself is working fine. IIRC, The plunger
controls pressure to a diaphram which allows more or less flow to the injectors.
Air flow past the vane raises the vane. 1st step is to find out why its not raising on its own.
Make sure all the intake boots are connected and not ripped.
Also make sure there is no binding. There is a bolt that holds the vane to
the lever, you can loosen that bolt and center the vane in the bore
then tighten.
09-23-2009, 08:46 AM
#14
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More likely than a problem with the air flow meter (which is the plate you're lifting) - the warm up regulator aka control pressure regulator is shot, due to sitting, and the pressure is incorrect. This would be verified by the correct CIS gauges, as jdgunn said.
That said - check first for vacuum leaks etc. Ignition timing too...
That said - check first for vacuum leaks etc. Ignition timing too...
09-23-2009, 04:29 PM
#15
Three Wheelin'
Thread Starter
More likely than a problem with the air flow meter (which is the plate you're lifting) - the warm up regulator aka control pressure regulator is shot, due to sitting, and the pressure is incorrect. This would be verified by the correct CIS gauges, as jdgunn said.
That said - check first for vacuum leaks etc. Ignition timing too...
That said - check first for vacuum leaks etc. Ignition timing too...