2003 Buick Regal rough idling

Tiny
STEPHEN KARANJA
  • MEMBER
  • 2003 BUICK REGAL
  • 3.8L
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 150,000 MILES
I just got done with a head gasket job on this vehicle. And thanks to you guys with your help about how to resolve a rocker arm and pushrod problem that I had. The car drives fine as long as you"ve got your foot on the gas pedal. However when you come to a stop, it shakes and idles very rough. Has a check engine light that's on. And code is po300. Radom misfire. So far I have replaced spark plugs cleaned injectors checked for vacuum leak the only thing that I have not replaced is spark plug wires. The problem has not disappeared. What else could I be missing. And also how come it drives so well on the freeway, the problem only shows up when I come to a stop. Tell me how I can send a donation you guys are well worth it.
Monday, July 28th, 2014 AT 2:44 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Are you certain there are no vacuum leaks? Also, have you checked fuel pump pressure to make sure the regulator is doing its job and not providing too much pressure?

To be honest, a vacuum leak is felt more at an idle. Once you rev the engine, the air fuel mixture isn't as off as when it idles. So, double check that and make sure the idle air control valve (IAC) is working. The IAC is responsible for maintaining a smooth idle.
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Monday, July 28th, 2014 AT 5:42 PM
Tiny
STEPHEN KARANJA
  • MEMBER
  • 47 POSTS
Thankyou so much Jacobandnicolas.I'll take your advice and recheck vacuum leak. And fuel pressure.
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Tuesday, July 29th, 2014 AT 9:01 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Let me know what you find.

Joe
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Tuesday, July 29th, 2014 AT 7:38 PM

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