Vibration at idle while warming up?
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Joined: Jan 2012
Posts: 72
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From: Tucson Arizona
Vibration at idle while warming up?
Puzzler folks! 100K miles...well maintained...but a couple of months ago the thing began vibrating at idle from a cold start. Even worse if in gear at a light. It's even still there when the water temp hits normal at or about 200. I'd say you have to drive for about 10 or so minutes until it's smooth/normal again at idle. By the way it's always smooth as normal above idle.
My Chevy Tech told me to open up and lube the intake valves, etc. Did that. Zero change. IDEAS?
Thanks!
My Chevy Tech told me to open up and lube the intake valves, etc. Did that. Zero change. IDEAS?
Thanks!
Thread Starter
Advanced
Joined: Jan 2012
Posts: 72
Likes: 2
From: Tucson Arizona
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Lube the intake valves...???
No codes, is that with a robust GM scanner?
New plug wires & plugs...suspect...is this when the issue began or an attempt to fix?
My guesses fall to gas or spark.
Certainly could be throttle body related as mentioned above...loose connection wire (known to occur) or carbon build up on blade.
(Lube the intake valve implies to me the tech thinks it is carbon build up.)
Easiset...
1) Add a maximun dose of Techron for a few tanks, run high rpms, in an effort to clean out the fuel injectors.
2) At cold start inspect the spark plug wires for a misfire, plus look for a crack in a coil. A a trick, in the night/ dark/ no lights, do a cold start and looks for a visible spark.
Next...
1) Have a robust GM scanner hooked up at cold start, look for codes (easy) or abnormalities (skilled).
2) I'd say you need to identify which cylinder is misfiring (if it is only one) and perhaps inspecting your new spark plugs before you do anything could be a good idea and lead you in a direction.
Hardest...
1) Search for a frayed, pinched or loose wire "anywhere".
2) Could be an intake leak...but I don't think so as the rough idle is not constant...but perhaps once metal/ plastic expands the leak seals...such as the intake manifold to heads or throttle body to intake manifold. (Spraying some starter fluid around these areas when cold starting to see if the idle increases is a home mechanic test.)
All FWIW good luck.
Let us all know what the cause was.
No codes, is that with a robust GM scanner?
New plug wires & plugs...suspect...is this when the issue began or an attempt to fix?
My guesses fall to gas or spark.
Certainly could be throttle body related as mentioned above...loose connection wire (known to occur) or carbon build up on blade.
(Lube the intake valve implies to me the tech thinks it is carbon build up.)
Easiset...
1) Add a maximun dose of Techron for a few tanks, run high rpms, in an effort to clean out the fuel injectors.
2) At cold start inspect the spark plug wires for a misfire, plus look for a crack in a coil. A a trick, in the night/ dark/ no lights, do a cold start and looks for a visible spark.
Next...
1) Have a robust GM scanner hooked up at cold start, look for codes (easy) or abnormalities (skilled).
2) I'd say you need to identify which cylinder is misfiring (if it is only one) and perhaps inspecting your new spark plugs before you do anything could be a good idea and lead you in a direction.
Hardest...
1) Search for a frayed, pinched or loose wire "anywhere".
2) Could be an intake leak...but I don't think so as the rough idle is not constant...but perhaps once metal/ plastic expands the leak seals...such as the intake manifold to heads or throttle body to intake manifold. (Spraying some starter fluid around these areas when cold starting to see if the idle increases is a home mechanic test.)
All FWIW good luck.
Let us all know what the cause was.
