90 Accrd surging idle in park when warm

Discussion in 'General Motoring' started by klijam64, Jan 30, 2005.

  1. klijam64

    klijam64 Guest

    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

    Any ideas?

    Thanks folks!
    klijam64, Jan 30, 2005
  2. klijam64

    motsco_ _ Guest


    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.

    motsco_ _, Jan 30, 2005
  3. klijam64

    Remco Guest

    Since the RPM surges when you go from P to reverse, I wonder if your
    load sensor is bad. The load sensor is supposed to sense a change of
    electrical load and adjust the idle accordingly.
    In your case, the reverse light obviously is turned on and possibly
    this is detected by the load sensor. Maybe your sensor is just too
    sensitive and causes surging.
    It could also be a vacuum leak somewhere.

    Remco, Jan 30, 2005
  4. klijam64

    klijam64 Guest

    Thx for the response. No I havn't bleed the system lately. It's been
    a year or so that I'v changed the fluid, so i suppose it's about time
    anyways. I know how to bleed the coolant when refilling w/the bleeder
    screw, but can the system be bled while it is at capacity? My brother
    told me to run the car w/the rad. cap off untill the thermostat opens
    and you see coolant flowing.
    klijam64, Jan 31, 2005
  5. klijam64

    TeGGer® Guest

    wrote in

    Not usually necessary.

    After you refill the system using the bleed screw (make sure the heater is
    turned to FULL HOT), start the engine, then bounce the bumper and squeeze
    the upper hose once in a while. The level will blip down as bubbles are

    Once it stops going down but keeps rising, put the cap back, make sure the
    reservoir is full, then drive the car around until the temp gauge reads
    TeGGer®, Jan 31, 2005
  6. klijam64

    klijam64 Guest

    Thanks for the info 'Teg... It'll be until next weekend that I get a
    chance to replace my coolant, so I'll post back then.

    klijam64, Jan 31, 2005
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