Hello,

I am a new member, just joined, just bought a honda as well. I have a slight problem. I will try to explain it as best as possible.

When you are driving the car and go to change gears, when I depress the clutch pedal after letting off the gas, the engine revs up around 1000-1500 rpm more than when I started to change the gears.

Now, if I get to my rpm that I am going to change gears at and let off the gas to change gears but wait about 2 seconds to depress the clutch, then the rpm's drop down like they are supposed to.

I have talked to 1 mechanic and 1 guy who is a Honda racing guy (mainly newer FI models). The mechanic says it is dirty carb. The other guy says it is a choke problem.

Also, after running the car for 30 mins or more, when I turn off the car wait about 2-5 mins, I crank it up and it acts like it is cold. Revs up to 2500 rpm or so. I press the gas several times and sometimes it will come back down and others I just have to start driving to get it back to idle.

Please help, need to fix cause it is really annoying.

Thanks

 

There is a thermovalve that is probably wearing out in the intake manifold. It controls the high idle, and when they get old, they tend to take much longer to heat up and actually open up. There is one that controls your high idle when the coolant is cold. You will probably need a factory service manual to figure out which one it is and where it is. They are only about $20 on eBay.

The thermovalve could be acting up if your car is low on coolant. If there is an air bubble in your cooling system, or the coolant is low, the thermovalve basically has no coolant to heat up from, and it always acts like your car is cold, hence the high idle.

There is also an idle delay mechanism on the carburetor that is supposed to help keep the RPMs up between shifts. It should barely be noticable, but if yours is holding the revs up too long, it may be sticky or need to be cleaned, or could be still related to the other problem you were having. Again, a service manual is going to be your friend.

Each of these systems will be laid out in detail, how they work, how to test them, etc. If you get that manual, it will unlock the world of mystery around that dark vacuum-infested carburetor.