If idle adjustment is done w/o diagnostic tachometer, are we just approximating what it should be at (770, +/-50 RPM) by the on-board dash tach? I've included a view of mine at normal operating temp, no load.

I'm unsure what the delineation marks on the on-board tach represent, so I definitely need help with that.

(Also, do I need to start a new thread to ask about how, as you can also see, the normal operating temperature is always low like that? It warms up fine, but only to there. Would draining-diluting the anti-freeze some, get it closer to the midline, or does this look ok?)

Any advice would be appreciated, Thank you.

 

I'd say that temperature gauge reading is GOOD. Same with the tach.

Hondas normally read there & not at the halfway mark like many other cars do.

Immediately above the zero mark of the tach, is a bold line for 500. Then a thin line for 750. Then the bold line marked 1000. So it's idling at about 700.

You are NOT supposed to adjust idle like that. You're supposed to unplug the IACV, which will make it almost stall. Then you adjust it to 500 or 550 rpm. That's called the "BASE" idle.

 

Thank you, JimBlake. Sounds good. I did see proper IACV/"base" procedure you mentioned in my manuals, and would actually follow that if ever need be.

Excellent! One less thang!

 

I should've said more about the temperature...
Once you know where your gauge normally points, a good thermostat will hold it there pretty solid while you're driving.

If you idle a lot in traffic (during summertime) it can go to the 50% mark or a little above, before the electric radiator fans start up.

 

So i take it my tach meter is wrong lol its above 1 like at 1 and half. the car runs fine tho it has given me problems. so is that ok? or should i get the idle speed still adjust?i just bought it a couple of days ago.its a 97 accord lx 2.2 at.

 

I would think an idle adjustment would be recommended. An idle @ 1.5K RPM is pretty high, unless its temporarily intentional to keep engine from stalling, but it doesn't sound like that's your situation. Your computer could be raising idle speed to compensate for other problem(s), or idle speed could have been adjusted up by previous owner for reason that you could determine when you lower it to proper level.

 

With a 1997 (or earlier) it's more likely due to the FITV (fast-idle thermo valve) bolted to the underside of the throttlebody. People have had to open that up & tighten the plunger inside. The computer has more active control over idle on 1998+ cars.

The FITV lets extra air bypass the throttle plate. As the engine warms up, it closes. When the engine is fully warmed up, it's supposed to be completely closed. Once that's OK, there's a few other things to check...
- Find & fix all vacuum leaks.
- Bleed ALL air out of cooling system (really).
- Clean out the throttlebody so no crud around the bore where the throttle closes.
- Make sure the throttle cable goes a bit slack. Cable MUST NOT be used to adjust idle.
- Make sure the throttle plate closes. Mechanical stop-screw is not used to adjust idle.
- Find the idle-air needle valve recessed in a hole above the throttle bore.

- All loads (AC, lights, blowers, defoggers, EVERYTHING) turned off.
- Warm up the engine completely, unplug the wiring from the IACV.
- Adjust idle to 500 - 550 RPM.
- Turn it off, plug the IACV back in, let it cool down COMPLETELY, reset your ECU.
- Start the engine without touching the gas pedal.
- Let it warm up completely without touching the gas pedal.

Honda idle-control system can sometimes be finicky. When someone tries to adjust the idle using the cable, or tries to adjust it while the IACV is plugged in, the system tries to fight the adjustment and everything gets farbed up...