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RarlyL8 RarlyL8 is offline
Crotchety Old Bastard
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Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,525
Alan - thank you for the '86 WUR info. It turned out to be a missing piece to a WUR puzzle I had a couple of years ago.

A buddy of mine was having issues with his 930 so I lent him my adjustable WUR for a few days. I had a -153 WUR laying in a box so I tossed it on and took the pressure readings. They were is spec so I ran it for a few days with no issue. Turns out that the -153 is the '86 WUR we are speaking about now.
The reason I think it worked in my car was that my fuel head was set at 90psi. The system pressure will affect all others so it likely brought the -153 WUR into spec for use with my engine. Many other bench tests were done on that unit to figure out how it worked. The various year WURs have slightly different features but all work basically the same.
I do not know why the '86 has higher spec pressures. It could be that more cylinder cooling was added to the smog motor via more fuel - this is pure speculation.

As for your cold start issue, I cannot remember off the top of my head at what temperature the cold start valve is taken off-line. At any rate, on a hot (95F) day you should be able to start the engine without the valve, it just takes a few more revolutions of the starter to get things going. There is one fellow here on the board who has removed his CSV and does fine in a warm climate.
The put-put-put is very typical of a lean start caused by slightly high cold fuel pressure. By slightly high I mean in spec but on the high side. It can be that finnicky. If you can tap the plug just a smidge and get it to mid spec this problem should dissapear. If not you have hurt nothing and the cold pressure will be spot-on.
As for the rich warm condition it really does sound like your WUR is taking a dump. Try installing the '79 WUR and take pressure readings. If it is in spec hook up your A/F gage and drive it until warm to see how she acts. You will do no harm and there is nothing to lose by trying.
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 07-08-2008, 06:37 PM
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