LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Running rich at idle

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Old Sep 17, 2008 | 08:50 AM
  #1  
stvski80085's Avatar
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From: Lake St. Louis Mo.
Running rich at idle

Well i have replaced the spark plugs, wires,opti, and one o2 sensor. It runs good but I can smell the gas when it starts. What should I be looking at? I have checked for vac leaks and can't find anything. I do think my cat may be going bad because of a rattle I get from that area. The rattle only comes when shifting though so i still need to hop under again and double check that. Just wondering if there is anything else to check.
Old Sep 17, 2008 | 09:05 AM
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From: College Station, Texas
Cats will definitely rattle when going south. Who tuned the vehicle and is this a new issue? Also, have you a put a fuel pressure gauge on it?
Old Sep 17, 2008 | 09:20 AM
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I have not put a fuel pressure gauge on it. i just bought this car about 4 months ago. been getting the kinks out of it. It runs great but i think it's rich when i start i up. It may be fuel related because it normally has to turn over a few times before it starts. Once started it's perfect. Fuel pump? I will need to get a gauge and check it and see what the pressure is.
Old Sep 17, 2008 | 03:51 PM
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leaky injectors?
Old Sep 17, 2008 | 06:39 PM
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Does is smell of fuel mainly on "cold" starts, or on both "hot" and "cold" starts? The PCM richens the mixture for cold starts, then leans it out as the coolant warms up. Do you have a cat?

When you check the fuel pressure, watch how quickly the pressure bleed off when you shut the engine down. A rapid loss of pressure can cause extended starting periods. That can be due to a bad check valve in the fuel pump, a leaking fuel pressure regulator or leaking injectors.
Old Sep 17, 2008 | 07:17 PM
  #6  
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I only notice it when it is a cold start. I guess it could be normal. I wish I had a scanner or the other programs that would tell me what the pcm was doing. Like i said though i have had no plug fouling at all and the car runs great with lots of power. just noticed the smell at startup. I do need a new cat for sure though. I plan on getting one next week. It also has a new fuel filter too.
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