The rpms on my 92 VX Rise to 1000 when I’m Idling if the Headlights are on. I hope that’s a neat clue for someone out there. I haven’t found this symptom anywhere. I have the shop manual. My mpgs aren’t what they should be (low40’s). I drive 50-60 on the flat. I’m at 0’ - 100’ elevation. Northern Pacific coast, Humboldt County, California I coast like she’s a roller skate. I keep the rpms at or under 2000 unless accelerating.

I lost :( a reference that said to set the base idle with the lights ON. I think.

  • Welcome to the site @MichelleWalker. As SolarMike says RPMs rising when the lights are on is normal, the mileage problem is a separate question you should post independently of this one. In it it would be good to know how bad the mileage is, and if it has changed radically recently. If you have OBD codes listing those too would help. – GdD Jul 23 '18 at 8:19
  • Thanks for the welcome! I understand the load raises the rpms, but it jumps up from 700 to 1000 and stays there. I have the shop manual and the sections for troubleshooting. I need an (affordable) external tach according to another advisor to reset the base idle. Sound ok? The mileage is down 3-4 mpgs. – Michelle Walker Jul 24 '18 at 18:04
  • It's not a bad idea to get one if you really want to be detailed with the tach readings @MichelleWalker. I'd be tempted to just adjust it up a bit without one and see if I'm happy with it before I invest in one, but it depends on how deep you want to get. I'd recommend an OBD reader as an essential tool to diagnose other issues and clear codes. I think the 92 civic uses an OBDI and opposed to II reader. There's questions about diagnosing MPG loss on this site, have a look as there's loads of information. – GdD Jul 25 '18 at 8:20

If the idle rises when the headlights are put on, then this sounds normal - the alternator is producing more power, so the engine speed is increased so it does not stall and can cover the extra load.

  • It revs up though and stays at 1000. I am going to follow the instructions in the shop manual to reset the idle from step one. Or have the mechanic who played with the nuts and screws. – Michelle Walker Jul 24 '18 at 17:37

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