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I had the stalling problem on decel for about a week after installing the LWF, only about 3 red faced incidents at traffic lights and then it seemed to cure itself. Some have said the DME “learns” the new flywheel and compensates; seems like this might be true.
Does require a bit more finesse when accelerating from standstill though, since the new clutch carries less mass/momentum so is more prone to stalling.
I used the 996 116 015 32 disk. At the time I seem to recall the 996 part was far more reasonably priced than the 964 part.
I only notice additional noise at idle with clutch out, sounds like nuts swirling in a metal can. I also notice a "clunk clunk" sound when the clutch is suddenly released with the drivetrain loaded (I.e. when inching forward and you stab the clutch back in and the drivetrain unloads). The clunking sound bugs me more than the nuts in a can sound, but neither are terribly obnoxious.
I installed the RS 4.0 GT3 flywheel which a lightened version of the 964 flywheel that is 3 pounds lighter with all mass removed from periphery, so a big change in polar moment of inertia. I found I had an issue with the engine reliably returning to idle and upping the idle speed and injector coast down restart RPM didn't fix the problem.
What fixed the problem was, along with the above, readjusting the base opening of the ISV by a few degrees and now it stalls about the same frequency as a stock 964 RS which is tolerable. When doing some research, I found the same Bosch ISV is OE to several cars - some with around 1/2 the displacement of the Porsche, so the base opening has to suit a smaller engine and the slow coast down of the dual mass flywheel allows the system to catch up in opening the valve.
I installed the RS 4.0 GT3 flywheel which a lightened version of the 964 flywheel that is 3 pounds lighter with all mass removed from periphery, so a big change in polar moment of inertia. I found I had an issue with the engine reliably returning to idle and upping the idle speed and injector coast down restart RPM didn't fix the problem.
What fixed the problem was, along with the above, readjusting the base opening of the ISV by a few degrees and now it stalls about the same frequency as a stock 964 RS which is tolerable. When doing some research, I found the same Bosch ISV is OE to several cars - some with around 1/2 the displacement of the Porsche, so the base opening has to suit a smaller engine and the slow coast down of the dual mass flywheel allows the system to catch up in opening the valve.
Make sure your ISV is gleaming clean on the inside. I actually started with a new one myself.
The valve pictured is for a 1995 993
Originally Posted by John D. Hmmm - I just did this.. Today....
Remove the ISV and scribe the metal and the grey plastic so you can get back to the original setting...
Next - take a sharp SMALL jewelers screwdriver, and remove the epoxy from the 3 holes you'll see. Under the epoxy are 3 allen screw heads. Clean enough epoxy so you can get to the screws.
Next - loosen the screws a bit, and turn the plastic part (the electrical connector) about 3 degrees COUNTER CLOCKWISE.
Next - tighten one screw head so nothing moves.
Next - reinstall the ISV and start the car.
Next - if the idle isn't right (mine is set at 890) - loosen that one screw head, and turn the base (the grey part that the electrical connector is molded into) about 1 degree. Let the engine settle.
Next - repeat the previous step as needed. If you go too far - turn it back, and start over - the ISVs are VERY sensitive as is the idle as you adjust it...
Next - when you are set - tighten all three heads.
JOhn
Photo from mr_bock with added text (note actual screws removed here):
That’s great info. It seems as 964 guys aren’t able to do this but they gave me the idea of just drilling a small hole in the valve to allow more airflow at idle. I’ll check it out.
That’s great info. It seems as 964 guys aren’t able to do this but they gave me the idea of just drilling a small hole in the valve to allow more airflow at idle. I’ll check it out.
Pete
On a 993 the throttle plate is closed completely and ALL the engine's air at idle comes via the ISV. There is an adjustment for the throttle plate on the 993 that is just like the adjustment on a carburetor; if a 964 has a similar throttle plate adjustment you may want to try tweaking that open that a touch rather than drilling holes. Just a thought - no experience at all.
That’s great info. It seems as 964 guys aren’t able to do this but they gave me the idea of just drilling a small hole in the valve to allow more airflow at idle. I’ll check it out.
Pete
On a 993 the throttle plate is closed completely and ALL the engine's air at idle comes via the ISV. There is an adjustment for the throttle plate on the 993 that is just like the adjustment on a carburetor; if a 964 has a similar throttle plate adjustment you may want to try tweaking that open a that rather than drilling holes. Just a thought - no experience at all.
I was thinking regarding many post it was another option
so with the LFW the only option is the "normal" 993 RS disc ?
Yes, that is the case. One thing though is the noise is not related to the disc it is related to the periodic oscillations of the crankshaft as it turns. Each cylinder firing creates a period of acceleration and deceleration as the crank turns - it is not smooth like an electric motor. This excites the gears and they rattle in the case creating a noise. A dual mass flywheel has two metal masses connected by an elastomer or spring to absorb the oscillations. The 997.2 GT3 assembly is 3 pounds lighter than the 964/993 unit and complicates stalling issues.
11-30-2018, 03:34 PM
