Re: 1988 Honda Accord won't idle when warmed up

Gee, M.A. Stewart wrote:

>
For the OP, this ground problem could be ruled out by simply using
a lead from a VOM meter. By taking the sharp pointy end of the
lead, and getting a good connection on the slow mixture valve (at its bracket where the hold down screw is), and connecting the other end of the lead to the battery negative post, the car would idle, if the ground was the culprit. A helper would be needed to hold the engine speed up, to prevent stalling. With a good connection, the helper lets off the gas pedal, and the engine would then idle.

With a manual trans carb Accord, the normal operation of this valve can be
felt while driving (its subtle). The valve is suppose to close (no fuel supply to the idle circuit) above 15 MPH/24 [Km/h] (approximately 1700 rpm in second gear). Coast down from 2500 rpm, in second gear, to about 1200 RPM and you can feel the valve open (fuel supplied to the idle circuit) at approximately 1700 rpm. The deceleration from
2500 (or above) down to when the valve opens, is very consistent. When the valve opens (idle circuit now receiving fuel) the deceleration is less (engine receiving a fuel mixture from the idle circuit and providing a little power).

A switch on the clutch pedal overrides the fuel cut off (opens the valve) when shifting gears.



Gee, I should have thought of opening the hood in stop and go traffic, jumping out and jambing a lead from a VOM meter into the "slow mixture
valve", which I was careful to call the "primary slow mixture cut-off solenoid valve" as in the factory service manual, IN TRAFFIC. It was INTERMITTENT! Meaning it would happen when the car was warm, and when I would least expect it to happen. As the OP said, it only happens when the car is warmed up, or in other words, in TRAFFIC!

It's an intermittent ground. They don't like to do bad things when you're watching.

I think it is actually a poor design. But that's moot since no Honda has had a carburetor for at least 15 years? (?).

dan
.

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