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Topic: voltage affecting idle/power??

in Forum: C3 Engines


voltage affecting idle/power??

Posted: 7/6/05 2:42pm Message 1 of 6
Former Member
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Estero, FL - USA
Joined: 6/1/2005
Posts: 6
Vette(s): 1972 Stingray coupe, numbers matching, all original unrestored (except has been repainted Mille Miglia red instead of Warbonnet Yellow), 72372 miles, base motor, automatic w/ factory air.
Here's one. Recently my perfect running car would not rev over 2000 rpms under load and had no power. I limped home and checked ignition, etc. all seemed fine. After revving a few times, power and throttle response returned but idle is erractic and "hunts" between 650 and 1000 rpms. I also noticed dome lighting getting brighter and dimmer erractically but not in unison with idle. Ignition system is stock. Can voltage regulator and/or alternator output affect these things?


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voltage affecting idle/power??

Posted: 7/6/05 8:25pm Message 2 of 6
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Portland, TN - USA
Joined: 4/29/2003
Posts: 805
Vette(s): 1972 Coupe Anything, but Stock and more mods to come! SSBC Force 10 Brakes, 3.73, TH350, 355 CID, Rack and Pinion, Vette Brakes suspension front and rear.

Not related to a corvette, but I have owned my toyota truck since 1987 and any time it experiences the conditions you described above, it always turned out to be wires, cap, rotor and plugs.  After I changed them it would rev fine.  I would check resistance on the wires with an ohm meter.

Surprising it can be that simple the cores in the wires just burn up and can not carry the energy of the spark to the plugs.  Finally plugs foul and the rotor just gets burnt up and the contacts in the cap overheat to the point they won't conduct.

 

 




voltage affecting idle/power??

Posted: 7/6/05 8:30pm Message 3 of 6
Former Member
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Portland, TN - USA
Joined: 4/29/2003
Posts: 805
Vette(s): 1972 Coupe Anything, but Stock and more mods to come! SSBC Force 10 Brakes, 3.73, TH350, 355 CID, Rack and Pinion, Vette Brakes suspension front and rear.

Something else I wanted to add.  The condition had no affect on lights dimming on the dash.

That could be related to a bad altenator, but usually when they go bad the ignition will start missing and the car usually just dies all together.  You will also see a dimming of the headlights and dash lights.  You can usually limp home as long as system voltage stays above 9 volts on a stock ignitions system, after that everything goes dead.  




voltage affecting idle/power??

Posted: 7/7/05 12:24pm Message 4 of 6
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CUYAHOGA FALLS, OH - USA
Joined: 12/2/2003
Posts: 6424
Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!

Actually, it may be related.  If the engine drops under the intended idle, the alternator output can drop, and the lights dim.   When the RPM comes back up, the lights brighten back up.   But that makes them surge with the idle surge, and does not seem to be the case here.   Just thought I would metion it.

I would check the alt belt, alt, and regulator as well as bad electrical connections for the surging lights.




voltage affecting idle/power??

Posted: 7/8/05 6:24am Message 5 of 6
Former Member
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Estero, FL - USA
Joined: 6/1/2005
Posts: 6
Vette(s): 1972 Stingray coupe, numbers matching, all original unrestored (except has been repainted Mille Miglia red instead of Warbonnet Yellow), 72372 miles, base motor, automatic w/ factory air.
Problem is intermittent as far as power loss goes. Now engine revs great under load and has great power but idle still "hunting".???? I afraid to leave the neighborhood with it because I can't pinpoint a cause. I guess I'll have to wait for it to reoccur as alternator/regulator outputs are normal now that it is running ok.


voltage affecting idle/power??

Posted: 7/8/05 7:30pm Message 6 of 6
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sonoma, CA - USA
Joined: 8/9/2002
Posts: 784
Vette(s): 72 LT-1 AC coupe,69 l-36 coupe
Here's a guess, check the fuse box connections where the electrical harness's plugs into the engine side of the firewall on the driver's side under the steering column, they are the engine and chassis electical   harness's there are two seperate harness's held in place with a screw, if the screw works it's way out they get loose, not to mention the dirt than gets thrown on them, also check all your grounds. anips38541.8217361111


in Forum: C3 Engines


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