problem! help

[davke]

ok, it seems everything was ok, but lately something got wrong. when i am changing a gear => turning loose an accelerator and the rpm should go down immediately, but mine gos up a little bit and after some time goes down. it is very annoying when i am changing the gears, so what could be wrong?? thanx

[bobafett]

does it do this when the car is warm?

its possible that if your fast idle is set too high 2500-3000 rpm (mine has done that before) that if you shift at 2600rpm, the car might want to rise the idle back up to 3000rpm instead of dropping.

if the car idles normal, around 800-1000, and you shift at 3000 and it goes up to 3400, and THEN slowly drops down, then you have another problem...

i know on the 86-87 EFI cars, there is a diaphram that keeps the car from dropping rpms too fast when you shift. but it should make the rpms SLOWLY DROP, not rise... but its possibly that you have a problem with that part.

[davke]

yes it does then my car is warm and car idles normal - 900. and i am changing the gears at 2200 mostly.
how can i set fast idle? and where is that diaphram? maybe i should to clean it or something

[bobafett]

what year is your car, and is it EFI or not? if its an 86-87 EFI there is a fast idle valve right next to your throttle body, hanging on the back of the intake manifiold. u can take it off and clean it all out. and also take the top off, and tighten it down a few turns to lower your fast idle. unscrew it to raise your fast idle. :)

[Robs89LXi]

Make sure all your mechanical parts on your throttle cable, gas pedal etc. are properly lubed and not sticking.

[davke]

ye, its 86 efi. mechanical parts seem to be good. i will try to do today what bobafett has sad. i gues the problem is there too becouse when i change gear on ~3000 rpm idles work normal - go down immediately. i think so :|

but there is another way: if i lower my fast idle, my engine wont spin to the end (until a limitation)? am i right?

[smufguy]

also what you have to do is, get some brake parts cleaner and clean off the throttle plate and TB mating surfaces. Also check to see how the return spring on the outside of the Throttle is. Sometimes they do get sticky. WHen i got my Intake manifold from the junkyard and bolted on, it did the same thing. I changed 3 different Fast Idle valves, and it was the same case. Opened up and cleaned the matin surface and the problem went away. Also, you would have this problem if the Intake Air Temperature sensor on the side of the throttle body is dirty and letting you run rich.

[davke]

where is that TB mating surface? and should i clean that air temperature sensor too?

[davke]

ok, i have cleaned throttle body, i have done what was possible. but i can't unscrew the temperature sensor, but it seems the enginne works a little better but not enough

[smufguy]

the only way to clean the IAT sensor (Intake Air Temp) is to take the intake manifold apart from the top (if you have a 88-89) and spray clean it with a carb or brake parts cleaner. Also, make sure that you stick a paper napkin under it before you spray it.

[davke]

i have cleaned IAT sensor, throttle body, fast idle valve, everything, but the problem doesn't go away. i guess the fast idle valve doesn't work well becouse my rpm still go up then an engine is warm. what u think?

[bobafett]

did you adjust the FAV? cleaning mine had no affect, but when i adjusted it by spinning the center part, and threading it further down, it effectively lowered and stabilized my fast idle.

[Kabuki]

Just so it is stated here, Honda does not recommend messing with FIV at all. It is set from the factory and should not be changed. Having said that, you can't just go screwing with it willy-nilly. Logically, the proper way to adjust it (and the method that worked for me) is to heat up some water to about 200*, and sit the valve inside of it. Wait for it to stop moving, and then screw down the adjusted until it closes off the passage. Make sure that you've added some thread locker or hondabond/ultragray to the threads to keep it in place. This may also be done while still installed, dpending upon the vehicle. I wasn't able to do it on the car on my 4G.