Honda Car Forum

Hi Robert

I have a similar problem as described below.
I have 97 Mazda Protege 1.5 L Auto Transmission

When I start the car in morning it idles at 1500-2000 RPM depending on
the outside temp. I live in east coast . after a min or so when i put
in drive more, the RPM is around 1000 RPM and it shakes a lot and the
RPM dances within rage on 50-100 RPM up and down, the Dash also
vibrates a lot.
As the car gets warmed and the temprature gauge comes in middle while i
drive the vibrations become much less. but still are there and the RPM
still dances sometimes. I can always feel roughness when the RPM is
under 1000 RPM.

If I go on ah highway then say for 10 miles and then stop at light the
RPM stops dancing for a while but then starts again..
I just had recent tune up with replacement of plugs, wires, rotor ,cap,
motor mounts changed, my mechanic doesnt have any more ideas.

I read frm internet that the IAC can be dirty. I went to Pepboys and
theys aid that it cannot be cleaned on this car and it may get ruined
if we put some solvent on it.

Please advise.

Thanks
Pankaj

Robert Isbell wrote:
> The reason why it's hunting is because there is most likely a vacuum
leak
> somewhere in the system. Keep in mind I can't see your car so it is
> impossible for me to diagnose it over this NG. I will just tell you
what I
> have seen at the dealer I work for, however you may find something
> completely different.
> The idle is set by the IAC (idle air control) allowing air to enter
the
> engine. The O2 sensor senses the lean/rich condition and that tells
the PCM
> to add or reduce the amount of gas injected (pulse width). The engine
is
> surging because there is too much air coming in, the PCM is
compensating for
> it by adding the proper amount of gas, raising the idle, but the IAC
is
> cycling trying to get the idle down. Find your air leak and you
should take
> care of the idle problem. I have seen intake gaskets leak, bad EACV
(IAC)
> valves, but mostly bad fast idle valves. I hope this takes you in the
right
> direction.
>
> Robert
>
> <roadboy@my-deja.com> wrote in message
news:9397jm$2qd$1@nnrp1.deja.com...
> >
> >
> >
> > Just got a '93 Accord EX, auto. Nice driving car with 240K kms
on
> > it. At first the idle would hunt up and down when cold then would
> > settle to 750rpm when warm. I didn't worry about it as my 86
prelude si
> > used to do the same. Recently I changed the battery, fuel filter
and
> > cleaned the throttle body. When I test drove the car the idle
continued
> > to hunt even when fully warmed up (could only notice this in
neutral or
> > park). I find that while the engine is running if I twist the the
> > throttle plate closed the hunting will stop. But as soon as I
> > accelerate and release the surging returns. I've tried cleaning
the
> > fast idle mechansim and the throttle plate again in case it was
sticking
> > but the idle continues to cycle up to 1500 and then drop to 750rpm.
> > Anyone solve this problem that I've seen on many other Honda's?
> >
> >
> > Sent via Deja.com
> > http://www.deja.com/