Fast idle thermovalve problem

Hi everyone,
I have a 90 Accord EX automatic developing idling problem, both cold
start and when at op temp. RPM is about 1100-1200 when cold, When
warm, it is 850-900. Today I tested suction at the upper port when it
is idling, so I thought it is leaking. I open up the FITV cover plate,
the suction at the port stop! Very puzzling. The idle air control
valve seem to work ok, I tested suction when cold ( lower port ) and
suction when warm, and when I disconnect the plug, suction stop. Any
suggestions, thank you for your time.

 

The "upper port" in what? The throttle body? The valve itself?

"Cover plate"? Are you quite sure this is the FITV you're attacking and not
the air boost valve?

Which port? And what part? FITV, EACV, or throttle body?

You're very vague in your descriptions. When you say the "plug", do you
mean the EACV's electrical plug?

How clean is the throttle body? Any cycling of the idle?

You need to be a lot more precise in your descriptions.

 

Hello Tegger,
Thank you for reading my post.
90 Accord Ex Canadian. Automatic.
Fast Idle 1100-1200 rpm, no fluctuation.
Warm idle 850 rpm holding steady,no fluctuation.
The fast idle speed is too slow, it will be a problem for me when it
is -30C. After the car warm up, I took off the air intake duct. At the
Throttle body,there are 2 ports. One at 10 o'clock position (upper
port) and one at 7 o'clock position (lower port ). Suction were felt
on both ports. When I unplugged the EACV , no suction was felt on the
lower port. the engine kind of stall and run at about 500-600 rpm. I
did some reading on the net and people says the upper port is the FITV
port and it should not be sucking air in when the engine is fully
warmed up, that was why I thought may be the FITV was leaking and
proceed to tighten the plastic ring. The FITV on my car has 2 heater
hose connected to it, one coming from the EACV. As I open up the FITV
which has a cover held by 2 screws, the plastic ring was quite tight
(I actually was not able to tighten it any further ) and when I
checked the suction again on the upper port with the cover still off,
there was no suction, put the cover of the FITV back on loosely, and
there was suction again at the upper port. The puzzling part was the
cover of the FITV shouldn't play a role. And I have checked the FITV
in boiling hot water, the pin moves up compressing the spring. I
should have strong suction when cold and no suction when hot, right?
Thanks again
Crw

 

what makes you say that? sounds fine to me. what's the spec per the
honda manual? have you had this car long?

 

Hi Jim,
Thank you for responging.
I had the car for 5 years now.The fast idle spec is 1400/+-200, I like
to see it around 1500. Usually in winter the engine will start
immediately and fast idle at 1500 rpm and gradually slow down as the
engine temperature is rising and settled at 850 when fully warmed up.
I started messing around with the FITV and EACV when the hot idle
speed was suddenly going to 1200 rpm and steady. No fluctuations. No
change with the Fast idle at that time. Now I got the hot idle speed
ok but the cold idle is too slow especially when I shift into D right
away without warming up the engine, rpm will drop to 700-800 rpm and
shaky. Now the day time high is in the mid teens and below 10C at
night, I got to resolve this quickly. Thx.
Crw

 

crw wrote:

--------------------------------------

Why is the fast idle speed so important? You're supposed to be DRIVING
the car during those critical warm-up minutes, at least if you beleive
your Owner's Manual)
Have you been careful to keep the reservoir full to MAX and have you
bled the air properly? Nothing else you can try will correct idling
problems if there's air in the cooling system of a '90 model.

'Curly'

 

buy the honda manual from helminc.com and set it up correctly. the
computer controls all idling behavior - you can't just "adjust" this
stuff and expect it to be fixed. if you have a problem, it's because
you have a malfunction. you need to find it to fix it.

two things to look out for:
1. blocked screen on the iacv. [idle too low]
2. vacuum hose leak. [idle too high]