2004 Pontiac Grand Prix Cold Start Problem-Must tap acceler

Tiny
FASTER18
  • MEMBER
  • 2004 PONTIAC GRAND PRIX
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 101,000 MILES
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.
Tuesday, October 20th, 2009 AT 10:47 PM

5 Replies

Tiny
MMPRINCE4000
  • MECHANIC
  • 8,548 POSTS
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).
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Sunday, October 25th, 2009 AT 10:19 AM
Tiny
FASTER18
  • MEMBER
  • 2 POSTS
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.
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Saturday, October 31st, 2009 AT 10:18 PM
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,548 POSTS
Glad to hear you figured it out.
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Sunday, November 1st, 2009 AT 7:59 AM
Tiny
GILAMAN4U
  • MEMBER
  • 1 POST
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?
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Monday, April 5th, 2010 AT 8:23 PM
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,548 POSTS
It was most likely a dirty MAF sensor, use a MAF cleaner available from most autoparts stores.
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Wednesday, April 7th, 2010 AT 8:47 AM

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