So, new to this forum and Honda cars. I recently inherited a 1992 Civic LX from my dad and it's having some idle issues which I'm hoping someone can help me with.

First, some history. Basically I don't know anything that was done in the past. Don't even really know how many miles are on it. At least 130K. Over that by how much I don't know. Anyway, I drove it home to work on it and the first thing I noticed is that once it warmed up the idle was really low, to the point where it felt like it would stall at a stop (never did but it was rough and slow). So, I started looking into the car to work on it and noticed an oil leak and a lot of oil in the intake.

Here is what I've done to the car so far. Cleaned the breather box and replaced hoses from breather box to PCV. The hose at breather box was completely clogged. Did not replace PCV as it still seemed good. Replaced FITV with new OEM unit. Removed and cleaned IACV (screen was pretty clogged as well). Cleaned throttle body and replaced throttle body gasket. I also replaced the fuel filter, air filter, spark plugs and the wires. The rotor and cap looked good so I didn't go any farther with that.

I have also done the oil pan, valve cover gaskets and new axles but of course this is unrelated.

Anyway, sorry for the long post, but now after all this work my problem has changed from the low idle to a fast idle. I start the car and it seems to idle a little over 2K up to about a little less than 2.5K and as it warms up it will go down slightly to remain right around 2K.

Not sure where to start with this. I'm not much of a mechanic and not very good at troubleshooting so hopefully someone can help me out.

Thanks

 

Just an update on some things I've tried since posting. Rotation distributor had no effect on RPM's. Removing hose from MAP to TB drops the RPM by about 1K. Turned in the idle air screw on the TB all the way in and it drops the RPM about 1K. Unplug the PCV tube to TB and it revs super high (3 to 4K). Not sure if any of this info helps but still hoping someone can point me in the right direction. Seems like these idle issues are so common with these things that someone would have a relatively easy step by step troubleshoot and fix write up.

Thanks in advance for any help.

 

welcome to the forum. have you tried to clean the idle cut valve. high idle cold usually is the ico valve dirty.

 

I assume the idle cut valve is the same as the IACV (Idle Air Control Valve)? I didn't clean the IACV (just replaced the screen because at the time I was worried what cleaners might do to it. Anyway, cleaning the IACV is my next move and then if that doesn't fix it I guess I need to check that it's actually working. I know I need to check for air leaks but not sure where to start on that.

Thanks for your reply.

 

Well, I'm still having problems, so if anyone can help here's an update.

I have now replaced the IACV and still have the same issues. I did try checking for vacuum leaks using a small propane canister and hopefully did it right. The RPM's didn't change at all.

I did take off the TB intake hose and checked that once warm the hole to the FITV is closing properly. I notice that the hole to the IACV still has bypass suction so I'm not sure why. What controls the IACV? Could this be a bad ECT? I haven't done a really go job of bleeding the coolant but I find it hard to believe that it would effect the RPM's to the point of being more than 1000 RPM too high.

Any ideas? Is there an easy way to test the ECT without having to remove it?

Thanks.

 

So, after a new FITV, IACV and bleeding the system it's still idling high. As a last resort (and I know I shouldn't) I adjusted the TB plate set screw. I turned it all the way then back in until I could just barely see the plate move then about a 1/2 turn more after that.

Now it seemed to lower the cold start idle to around 1200, where it should've been but once it warms up it starts surging from about 700 to 1200. Out of curiosity I stuck a .015 feeler guage between the set screw and that gets rid of the surging but it then idles at about 2000 again.

I'm stumped. Anyone out there that can help? Thanks.