Normal Idle on Tach?

[YukonCrazy]

2008 Yukon 5.3 Flex

What should be the normal idle on the tach sitting in gear at a red light with A/C running? I have been trying to diagnose why the Yukon has been idling rough that started about a month ago. I changed the plugs, wires, cleaned the MAF/TB. No change.

Sitting in gear at a stop light, the tach is moving slightly back and forth from 500 to just under 500. When it dips just under 500, it feels rough on the idle.

 

[Reester]

My 07 Avalanche is fully stock and at idle my RPM's range from 500-600 according to my scan tool.


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[AZSCTACO]

2008 Yukon 5.3 Flex

What should be the normal idle on the tach sitting in gear at a red light with A/C running? I have been trying to diagnose why the Yukon has been idling rough that started about a month ago. I changed the plugs, wires, cleaned the MAF/TB. No change.

Sitting in gear at a stop light, the tach is moving slightly back and forth from 500 to just under 500. When it dips just under 500, it feels rough on the idle.

Have you ever replaced the Alternator? Mine was doing this and I replaced mine. I figured mine wasn't getting enough amps at idle. Either my alternator was going or the voltage regulator.