1990 Honda Civic LX 1.5L - Schamatics and or Testing Information on Sensors and/or Vacuum

important: code 1 and erratic idle are not necessarily connected.

re code 1, that means you need a new oxygen sensor. and not just any old oxygen sensor, but either ngk or denso - bosch and other aftermarkets don't react fast enough and you'll have endless problems with them in a honda.

indeed.

/what/ other sensors?

all the information in the world won't help if you don't know what you're trying to do with it. fix the code first, then go back to the idle.

is the idle erratic like it hunts up and down, or is it simply uneven? if the former, check the coolant level, and for associated problems like head gasket. if the latter, check the idle valve strainer is not clogged, and replace the plugs/plug wires if they're old. make sure the idle base speed and ignition timing are set correctly.

now, if that makes sense, and you check each of those items, you can check out the factory workshop manuals here.

and of course, you can continue to ask questions here.

I'd just get the manual from alldata.

--scott