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Matt, Engineer
Category: Car
Satisfied Customers: 21627
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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1988 Camaro: Sport..idling, the rpm gauge goes

Customer Question

Hello, I have a 1988 Camaro Rally Sport. When I start the car, the battery gauge goes over half. When idling, the rpm gauge goes up and down and up and down. The car sometimes gives a little shudder, but so far it hasn't stalled out. It makes me nervous, though! I have a new battery, new distributer, and the battery and alternator were checked on the meter at a garage. They were both found to be fine. Also, after driving about 5 miles, when idling, the battery gauge sometimes goes down below half. Thank You!!!
Submitted: 5 years ago.
Category: Car
Expert:  Matt replied 5 years ago.

I'd check that the alternator is actually charging the battery in the car, by taking a battery voltage reading with the engine off then another with the engine running. The 2nd reading should be higher than the 1st and climbing steadily. And also check that the alternator is secure to the engine as this provides the ground for the charging circuit and make sure that the engine / gearbox earth strap is secure and the contacts are clean and bright.

also check that the main battery contacts are on tight and the contacts are bright and clean, do the same for the engine earth strap

if this is all OK it may just be a sticking idle speed control motor / valve as these get clogged up with carbon and some brake cleaner washed through helps free things off.

Matt and 7 other Car Specialists are ready to help you
Customer: replied 5 years ago.
Thank you!!! Is there any danger of my car stalling out? I drive in LA, CA!!
Expert:  Matt replied 5 years ago.

sounds like you're running close to that happening, try cleaning out the idle valve as a 1st action and check for air / vacuum leaks on the intake manifold

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.
Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.