2004 Pontiac Grand Prix Cold Start Problem-Must tap acceler

2004 PONTIAC GRAND PRIX
101,000 MILES • 6 CYL • 2WD • AUTOMATIC
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FASTER18
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I have a well maintained car and I consider myself fairly mechanically proficient. But I have been totally stumped by this problem. I have scoured resources on the Net and can’t seem to figure this out.
Here is the Issue: Every time I go to start my Grand Prix, I have to tap the accelerator when starting the car. If I don’t tap the accelerator then the car won’t start. I checked my fuel pressure and I have a strong 56psi and the fuel pressure seems to hold after sitting for awhile. I have changed the fuel filter for good measure. I have scanned the engine and my scanner shows no error codes and shows that all systems checkout correctly. The car always runs well and gets decent mileage. I cleaned the pcv valve and map sensor seems to be good. Please help me out.
Oct 20, 2009 at 10:47 PM
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MMPRINCE4000
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Sounds like the cold start valve, it adds fuel to engine while cranking for cold starting.

Remove valve, disable ignition and put valve (connected to connector) in glass jar. When cranking, fuel should squirt out injector (CSV is an injector).
Oct 25, 2009 at 10:19 AM
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FASTER18
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I fixed it. I read a post from a user having the same problem. He said to clean the throttle body. So I grabbed a can of Gumout Carb Cleaner and went to town on the throttle body. I could not believe how dirty it was. I had just ran some seafoam through the previous tank of gas. Anyway, i thoughly cleaned it with carb spray. The car now starts perfectly and runs even better than before.
Oct 31, 2009 at 10:18 PM
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MMPRINCE4000
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Glad to hear you figured it out.
Nov 1, 2009 at 7:59 AM
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GILAMAN4U
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My grand prix has the same issue. The inside of my thottle body is also very dirty do i need to remove it before i clean it with carb cleaner?
Apr 5, 2010 at 8:23 PM
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MMPRINCE4000
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It was most likely a dirty MAF sensor, use a MAF cleaner available from most autoparts stores.
Apr 7, 2010 at 8:47 AM