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AFD660's Avatar
 
Join Date: Sep 2008
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Trouble cold starting

Having problems with my 930 starting when cold. I'll crank it and it'll turn over run for about 1 second then die. Go back to cranking at it will just turn over. Eventually it will start, and sometimes I'll press on the accelerator pedal and it'll start. It starts just fine when the engine is warm or hot. I cleaned the air filter, and changed the spark plugs. Car runs fine and drives fine. These are what the old plugs looked like when I pulled them. The problem was there before and after I changed the plugs. Car is an 84 ROW 930.



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1984 930... Andial intercooler, GT35R, Zork tube, RarlyL8 wastegate pipe

Last edited by AFD660; 07-25-2011 at 11:02 AM..
Old 07-25-2011, 10:45 AM
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Cold Start Control Pressure is too high - adjust the WUR. You could also test this theory by [while cold]:
1. remove the air filter housing and expose the metering plate
2. have someone else try to start the car [with no gas pedal]
3. while the starter is turning, you push slightly on the metering plate [just slightly - maybe an 1/8"- 1/4"]. This will cause extra fuel to go into the the combustion chamber and should help the car to start immediately.
4. If this works, then you'll know your car is starving for fuel...

This would be a problem with your WUR. You'll need CIS gauges to test and see if your cold control pressure is within spec. If it is in spec, then your Cold Start Injector may be inoperable...
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LIVN80S - - Red '79 Porsche 930 Steel Slant Nose Conversion [in 1987] w. 46k miles 3.3L; 964 Cams; K27HF @ 1.0 BAR, with Garrettson Intercooler; Rarly Zork; CIS Flowtech Fuel Head & BL-WUR.

Last edited by mooney265; 07-25-2011 at 03:16 PM..
Old 07-25-2011, 03:09 PM
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What he said.
I might add that if you are in a warm environment the cold start injector is not needed to start the car. I set my cold pressure on the low side as I find it works best there.
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 07-25-2011, 05:53 PM
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All of the above is excellent advice. I will throw in one more wrinkle; I had similar symptoms (I know, it's hard to convey symptoms via the written word sometimes) but I would experience the car starting and running for for like maybe a second or less, then nothing. Crank, fire, and run for a partial second, then stop. It would not act up every time, usually every other day until it got to be a regular thing. Turned out to be my overspeed relay under the drivers seat. Sometimes it would allow the pumps to run, other times not or for just a brief second. Didn't seem to make any difference hot or cold, entirely sporadic. Since refurbishing the relay, I've been driving the car daily for a couple of weeks with no issues.

Your issue is certainly as already described, but if all else fails look elsewhere. Unplug your connector to the metering plate behind the fuel head to force the pumps to run with just the key in the on position. At least that way you have the piece of mind that the pumps are running before you crank the engine over.
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Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 07-25-2011, 06:48 PM
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Maybe this thread will help:

Tough cold start ideas ?
Old 07-26-2011, 08:21 AM
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I did what Mooney265 recommended and it started up when the metering plate was pressed slightly. Just need to get a set of gauges now and check pressures. Thanks for the help guys. New problem though, the engine misses/stumbles at higher RPM. Gonna change the fuel filter, check spark plugs, plug wires, cap and rotor, and for any vaccum or intercooler leaks. Thanks again everyone.
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Old 08-01-2011, 10:35 AM
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That means that your Cold Control Pressure [CCP] is too high. You'll need some CIS gauges so that you can check all of your pressures:
1. System Pressure [SP]
2. Cold Control Pressure [CCP]
3. Warm Control Pressure [WCP]
4. Boost Control Pressure [BCP] - for this you'll also need a Mitey-Vac/Boost

Before you start, remember to unplug the electrical connector at the WUR and start with a cold [sat overnight] engine...

Also, be aware that the higher the Control Pressure, the Leaner the Air to Fuel Mixture result.

You may also want to check your idle mixture, it may be too lean. The way I was taught was to wait until car fully warmed and then "slowly" push the idle mixture screw in. When you begin to feel pressure [the beginning of extra fuel being added], you'll need to notice your idle speed.
1. If it goes up initially, then your too Lean
2. If it goes down initially, then your too Rich

You'll want to try this excercise 3-4 times so that you consistantly know how it is effecting the idle speed... If it turns out your too lean, then you could adjust with 3mm allen wrench [[turn clockwise [to the right]] to Richen up the idle AFR... I'd turn 1/8 of a turn at a time. Then, redo the test and try to find the sweet spot where an extra 1/8 of a turn gets you in the "too rich" category and meet in the middle... A little winded but, I hope you get the picture...

Good Luck - Shannon
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LIVN80S - - Red '79 Porsche 930 Steel Slant Nose Conversion [in 1987] w. 46k miles 3.3L; 964 Cams; K27HF @ 1.0 BAR, with Garrettson Intercooler; Rarly Zork; CIS Flowtech Fuel Head & BL-WUR.
Old 08-01-2011, 02:16 PM
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