surging idle

[87AccordLXsdn]

if i just put the car in part, the idle will keep going from like 1k down to 800 then back up and it just keeps doing this. anyone know whats causing it?

[Honda77]

I have an '87 4-dr 5sp and it does the same thing when I sit at a stop light.

[Low Tek]

i don't know on carb models... I know on the FI cars it is the fast idle sensor.. behind the intake manni...

[superguillermo]

Can be anything to a vacuum leak, bad sensor, air in cooling system, etc...depends. Check your ECU codes and start doing some searches. good luck

[DanG86LX]

Pcv ?

[88Accord-DX]

I would replace the Positive Crankcase Ventalation valve mentioned. See what happens next & let us know. That would be something quick and easy to re-place and would see where you need to go from there.

[accordlxi2.0]

he has a carb model.
he has an "ecu", but has no dianostic codes.
well on my lx the surging idle was caused by me having low coolant and air in the system.
it's true on the side of the block is the "ecu" temp sensor.

on mines i start it up ( i disenganged the fast idle cam, so the ecu use's the idle booster) it'll rev and hold it's idle at 1,000rpms then once the gauge moves with-in the normal band it'll go down to the rpm's you set it to.

[Low Tek]

he has a carb model.
he has an "ecu", but has no dianostic codes.
well on my lx the surging idle was caused by me having low coolant and air in the system.
it's true on the side of the block is the "ecu" temp sensor.

on mines i start it up ( i disenganged the fast idle cam, so the ecu use's the idle booster) it'll rev and hold it's idle at 1,000rpms then once the gauge moves with-in the normal band it'll go down to the rpm's you set it to.

That was my next guess.. I know mine does that when I have low coolent.. maybe try and bleed the system for air... anyways, good luck and let us know

[A20A1]

That makes it sound like you have low coolant often... do you have a leak somewhere?

[Low Tek]

I have a bad hose somewhere.. I think I pin pointed it to a hose on top.. it has a slow leak, and I just have to replace it.. before it gets worse...