klijam64@email.pct.edu wrote:
> Hi folks,
> This has only recently started to happen.. my car is a 1990 Accord
> EX, Auto, with 178k on the clock. The only work I've performed on the
> intake was to clean the EGR ports(about 5months ago), and routine
> throttle-body cleaning.
> This only happens after the car has been warmed up and out on the
> highway. The rate of incident is increasing. After letting the car sit
> and warm up(very cold in PA this time of year) for 15-20mins, idle is
> fine, drives fine.
>
> After driving, when I put the gear into park, the idle will jump
> from 1000 to 1500rpm(will raise to 1500 over about two seconds, then
> drop sharply to 1000, and repeat). Putting the car into
> reverse,D4/3/2/1,or neutral returns the idle to normal.
>
> It's almost like when I shift from Park to Reverse: the idle raises
> for a second, presumably because the reverse gears are kicking in(???
> this is just an educated guess ???).
>
> The gear indicator *does* indicate it is in park. I have tried
> shifting up/down through the gears while the engine is off to possibly
> clean any bad contacts in the shifter unit. No good.
>
> I have unbolted the pulsed-air valve(on the intake manifold, the one
> with the small metal screen in it) and cleaned it with throttle-body
> cleaner. I also inspected the cold-start air valve per service manual
> directions(has the wax bi-metal and coolant lines in it to idle high
> when cold). I took the top service cap off, noted the air flow while
> cold, waited for car to warm up, and then observed no air flow(normal
> operation).
>
> Any ideas?
>
> Thanks folks!
> -Jamie


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

First thing I'd check is the coolant level. Rad must be absolutely full,
and coolant reservoir full to the line, otherwise air in the system can
fool some sensors. Have you bled the air bubbles out recently? Idling
your Honda to warm it up does nothing but bad for it. Water and acid
by-products in the oil / intake. Can ice up and clog the PCV valve.
Check what the manual says about warm-up time.

'Curly'