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'00 Z71 Rough Idle

67ChevyRedneck

By 67ChevyRedneck
in Ask A GM Technician

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67ChevyRedneck Enthusiast

67ChevyRedneck

Posted
Posted

Hey all, I'm new to this board. I just purchased a nice 2000 Z71 x-cab with 68K on it. When I bought it it ran like a smooth top. I've had it for 2 weeks and it seems like the idle gets a little rougher everyday, almost like a miss. It runs fine once I accelerate and going down the road. At idle it holds a constant 500 rpm in gear AND in park? Is that too low? It seems odd it would be 500 at both, I would have thought 700 or so in park and 500 in gear. I'm good with OLDER vehicles, this is my first one newer than '86 so please don't get all technical on me. I love this truck, but the idle really bothers me. Please help.

 

Also: I talked to a friend of mine and he's going to help me run some top end cleaner through it this weekend. Also: there are no "check engine" lights on. This truck came from indianapolis, In. and it's now in SC, could it be an elevation difference with different air pressures?

Frank S Senior Enthusiast

Frank S

Posted
Posted

500 RPM's is low for idle in park or in gear. Try finding a parts store or a friend and checking the fuel pressure for one as it may be somewhat low seeing as how the vehicle smooths out when you accelerate from what you say. The ideal pressure on your truck at idle should be 62 psi, though the vehicle can function with it somewhat lower.

 

If it comes in lower, start by changing the fuel filter and see if that helps. Retry the pressure gauge after the change and if it's still lower than about 57-58 psi you may be losing the pump.

USA1Fan Enthusiast

USA1Fan

Posted
Posted

I haven't paid much attention to my idle when in Park, but in gear it idles at ~500 rpm. My Z71 EC is a 2004 with the 5.3l, less than 10k miles / just over 6 months old.

67ChevyRedneck Enthusiast

67ChevyRedneck

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Posted

I know the idle can't be right. I tried to listen for the typical whining sound a failing pump makes, but I can't hear anything. It is still under Carmax's 30 day warranty. I'm bringing it back today. Any other suggestions?

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