High Idle on 95 Honda Civic DX (D15B7)

[creativedisco]

So, as mentioned in the subject line, I've got a 95 Honda Civic (DX) with a D15B7 in it. I'm wondering what sort of things I can do to diagnose this high idle problem and hopefully fix it (as in a first check for this, then check for this, then check for this sort of thing).

 

Here's the issue: Normally, my Honda idles pretty low. Sometimes less than 1,000 RPM. However, if I have to push the engine hard by accelerating quickly (say to avoid getting hit by some of these wonderful Atlanta drivers), the engine will suddenly start idling at above 5,000 or 6,000 RPM. One afternoon, I had to do this and ended up having to sit in a line of cars later on anyway. I sat for so long with it idling that high that it started to smoke and I could even smell something burnt coming from the car.

 

After a few days, the idling problem corrects itself. It'll gradually fall to around 3,000 RPM and then 2,000 and then eventually back to 1,000 or 1,500. I've also noticed that I can make it idle lower by hooking my foot beneath the accelerator and pulling up. Also, currently it's hanging at around 2,000 RPM (maybe a little higher), but isn't going back down any more than that.

 

Hopefully that information is detailed enough. Like I mentioned, I was wondering what I could do to diagnose what's going on.

 

I've tried listening for a vacuum leak with the engine running, and I do hear hissing, but I can't tell if that's my intake (I've got one of those intakes with the cone air filter on it) or actual hissing from a vacuum hose. I can't figure out where it's coming from.

 

Other than that, I'm stumped.

 

Thanks for all of your help!

 

-Travis

[Mac Lovin]

like you said vacuum leak throttle position or idle air control

[James Matteu]

Does the throttle cable move freely? Any binding or snags? Check it at the throttle body. Also remove the cable at the throttle body and see if the throttle valve itself is binding or hard to move.