Honda Car Forum

I've got an oscilating idle on our recently purchased 96 Civic Ex AT (112k
mi) with a new throttle body done just before we got it. Here's a synopsis
(warm engine): If I rev to 3000 rpm and let off the pedal, the idle drops
dramatically to 1000, then up to about 1400 then back down. Repeat the
1000-1400 oscillation a couple times, then finally to rest at a reasonable
(but maybe high) 1000 rpm.

Cold idle is about 1500 rpm; I hate engaging the AT at that engine speed.

Any ideas? I haven't got the service manual yet. Was there an adjustment
missed when the throttle body was installed?

Thanks a bunch.

Scott

After removing, cleaning and reinstalling the TB on my '94 Civic I had
very similar symptoms. Turned out there was a little fragment of old
gasket left between the TB and the intake manifold. The resulting vacuum
leak caused the fluctuating idle.

To find it, I filled a squirt bottle with rubbing alcohol and sprayed
around the various parts of the intake system with the engine running
(most people suggest using carb cleaner, but rubbing alcohol is all I
had at hand). When the spray hits the location of the vacuum leak you
will notice a dramatic drop in engine RPM.

Scott wrote:
>
> I've got an oscilating idle on our recently purchased 96 Civic Ex AT (112k
> mi) with a new throttle body done just before we got it. Here's a synopsis
> (warm engine): If I rev to 3000 rpm and let off the pedal, the idle drops
> dramatically to 1000, then up to about 1400 then back down. Repeat the
> 1000-1400 oscillation a couple times, then finally to rest at a reasonable
> (but maybe high) 1000 rpm.
>
> Cold idle is about 1500 rpm; I hate engaging the AT at that engine speed.
>
> Any ideas? I haven't got the service manual yet. Was there an adjustment
> missed when the throttle body was installed?
>
> Thanks a bunch.
>
> Scott

Clean the Fast Idle Thermo Valve.

I'll bet the car is a DX right?

--
Charles Tague
93 Honda Civic DX HB
1.6L SOHC VTEC 14.85 @ 89 mph,1.98 60 ft.
With ZEX 85 hp ZEX 13.09 @ 103 mph, 1.81 60ft.
86 Pontiac Trans Am
225/50/15 GForce Drag Radials
305 peanut cammed 15.29 @ 88 mph
http://home.cinci.rr.com/mistab0ne/
"Scott" <sbd@cox.net> wrote in message
news:hxuwb.51634$xV6.31607@lakeread04...
> I've got an oscilating idle on our recently purchased 96 Civic Ex AT (112k
> mi) with a new throttle body done just before we got it. Here's a
synopsis
> (warm engine): If I rev to 3000 rpm and let off the pedal, the idle drops
> dramatically to 1000, then up to about 1400 then back down. Repeat the
> 1000-1400 oscillation a couple times, then finally to rest at a reasonable
> (but maybe high) 1000 rpm.
>
> Cold idle is about 1500 rpm; I hate engaging the AT at that engine speed.
>
> Any ideas? I haven't got the service manual yet. Was there an adjustment
> missed when the throttle body was installed?
>
> Thanks a bunch.
>
> Scott
>
>

Nope, EX. Is that valve specific to the DX/LX configuration?

"Mista Bone" <MistaB0ne"nospam"@cinci.rr.com> wrote in message
news:adFwb.38677$kL2.7687@fe3.columbus.rr.com...
> Clean the Fast Idle Thermo Valve.
>
> I'll bet the car is a DX right?
>
> --
> Charles Tague
> 93 Honda Civic DX HB
> 1.6L SOHC VTEC 14.85 @ 89 mph,1.98 60 ft.
> With ZEX 85 hp ZEX 13.09 @ 103 mph, 1.81 60ft.
> 86 Pontiac Trans Am
> 225/50/15 GForce Drag Radials
> 305 peanut cammed 15.29 @ 88 mph
> http://home.cinci.rr.com/mistab0ne/
> "Scott" <sbd@cox.net> wrote in message
> news:hxuwb.51634$xV6.31607@lakeread04...
> > I've got an oscilating idle on our recently purchased 96 Civic Ex AT
(112k
> > mi) with a new throttle body done just before we got it. Here's a
> synopsis
> > (warm engine): If I rev to 3000 rpm and let off the pedal, the idle
drops
> > dramatically to 1000, then up to about 1400 then back down. Repeat the
> > 1000-1400 oscillation a couple times, then finally to rest at a
reasonable
> > (but maybe high) 1000 rpm.
> >
> > Cold idle is about 1500 rpm; I hate engaging the AT at that engine
speed.
> >
> > Any ideas? I haven't got the service manual yet. Was there an
adjustment
> > missed when the throttle body was installed?
> >
> > Thanks a bunch.
> >
> > Scott
> >
> >
>
>