Hey guys I have a 97 Civic LX that's giving me heartburn. Starting about a week ago, the idle RPM dips whenever under electrical load. When idling if I turn the wheel, turn the fan on, or turn my headlights on the RPM dips to around 300. Also randomly bouncing idle whether under load or not, anywhere from 1000 to 300. It's got new plugs, new battery, new dist cap and rotor, new fuel filter, and new ignition coil. Most of these were replaced before the problem started, I'm not just throwing parts at the problem.

I also seem to be having power loss when engine is at temp, especially when the AC is on. I'm probably going to replace the plug wires in the next couple days (they're kind of old) but I haven't noticed any arcing. Any advice on how to diagnose this problem would be appreciated.

Thanks,
TheFinder

 

Take off the alternator, take it to AutoZone, and have them test it for free.

The idle problem could be a few things. I would start by cleaning your IACV that is bolted on the back of the intake manifold. Clean the metal screen. Also for the idle, make sure there are no air bubbles in your coolant system. To remove them, start the car with the radiator cap off. As it warms up you will see bubbles. Keep adding coolant when needed and replace cap after you stop seeing significant bubbles.

Check the timing.

It is normal for the idle to dip when you switch on an electrical load. Mine will dip for a second then go back up. Or sometimes it lowers but never to 300 rpm.

What does it idle at under no loads at operating temperature? It is quite possible that your IACV is causing your bouncing idle AND the lower idle when loads are applied.

 

Thank you for the response, I should have added that I checked the alternator and it was fine, including the voltage regulator. I also burped the coolant system already. I also tried cleaning the IACV but I didn't replace it, replacing it could solve my issue it's just kind of pricey so I was hoping it was something else. Without a load it usually idles around 600 RPM, but sometimes it will drop to 300 even without a load for no apparent reason. This is especially true when I start the car while engine is at temp.

I'm not sure how to check the timing but I will look it up and try to do so. I guess instead of replacing the spark plugs wires (if the timing checks out) I should think about investing in a new IACV. Is there any way to check to make sure it's bad?