Gauges and rough engine when Ambient temp below 40 from cold start
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Joined: Mar 2014
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From: Texas
Gauges and rough engine when Ambient temp below 40 from cold start
I have a 1982 base vette with a few mods, 1985 ECM, small Cam, up graded fuel pump and mid size headers. When the outside temp started dropping under 40 degrees my gauges started acting like they lost ground and the engine started running rough. only from a cold start. When this happens and I let is sit and run for 10 to 15 minutes it will start running smooth and the gauges will snap back and start working normal. On days when it is above 40 degrees it runs fine and the gauges work normal. any ideas where to look or what may be wrong?
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Joined: Jun 2015
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From: Central Virginia
I have a 1982 base vette with a few mods, 1985 ECM, small Cam, up graded fuel pump and mid size headers. When the outside temp started dropping under 40 degrees my gauges started acting like they lost ground and the engine started running rough. only from a cold start. When this happens and I let is sit and run for 10 to 15 minutes it will start running smooth and the gauges will snap back and start working normal. On days when it is above 40 degrees it runs fine and the gauges work normal. any ideas where to look or what may be wrong?
I more than enough experience with electrical but not with Corvettes. This is the very first thing I would do even if it doesn't solve your problem.
Get a good multimeter and set it to resistance.
1. Check the negative battery terminal, that means check the post with a multimeter lead and check the terminal. You should get no more than .02 Ohms resistance. If it is higher .02 remove the negative terminal, clean reinstall and check again.
2. Repeat this everywhere there is a negative grounding terminal like engine to body, the negative side of the battery to the body, the grounding terminal that is close to the rear differential, everything.
3. After you check all negative terminals you can then check wires, especially those you suspect. End to end, terminal to terminal, though connections and at connections. A safe rule on short wire is .04 Ohms rom end to end. Longer wire allow for more Ohms.
4. Troubleshoot the temp sending unit.
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Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Drive it on warmer days, these engines are finicky in cold weather unless it has all the components on it that came from the factory. 
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Joined: Mar 2014
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From: Texas
problem is it has been running just fine in 20 degree weather for over two months before it started doing this.....something has changed....I checked all the grounds no problems found.....
