Sudden bad idle on a '87 EA82 GL Hitachi carb'd SW: why?

[jdub]

Many thanks in advance for you help on this idling problem. Car is an '87 EA82 Hitachi-carb'd GL station wagon. Problem is bad idle that appeared suddenly. I can't spend much money on this so I need to narrow down to what I can do at home in my workshop.

 

Drove car home from work, operates nicely, 1/2 a tank of gas. Park and wash. Restart later: idles high in choke mode, but barely holds an idle after warmup, instead holding at about 3-4hundred rpm. Later, cannot even hold this and dies (must rev. to keep from dying). Level, constant pressure on gas pedal produces uneven idle, but not a constant miss, just rough and uneven.

 

What I've done: Replaced gas filter @ tank, plenty of gas flowing from gas tank. Removed gas cap and ran: no luck, still bad. Filled tank with 92 octane. Checked choke cycle; carb butterfly returns to normal fine. Gumout down barrel. Inspected and replaced plugs (all OK). Air filter fine (ran with cover off: problem persists). Vaccum hoses all connected. Good (~12+v) current return at battery (no electrical problems whatsoever). Fuses all check OK, including those in eng. comp.

 

Have not checked gas flow at carb. Cannot find anti-diesel valve. Cannot check timing (no idle). Also, idle would increase or decrease depending on selection of Defrost/Heat using buttons prior to this problem (never caused under 800 idle however).

 

Anything obvious I should try? What could possible have happened to turn the car from idler to this?

 

Many thanks,

 

John

 

[robaru]

There is an idle speed adjustment screw on the botttom of the carb. Don't confuse it with the air screw. Turning it in should increase the idle speed. Try it after you warm it up. Did you wash the motor when you washed the car? You might check the disty cap for water.

[jdub]

Thanks for the reply. I was careful not to get any water in the engine bay, and did pop the dist. cap to check it and the rotor.

 

Jw