On an '88 Accord DX with auto tranny:
Anyone know what the full operation of the air vent cut-off diaphragm is? It is the diaphragm built into the side of the carburator thermovalve which is on the upper front drivers side of the carb. Mine has a bunch of holes from being so close to the fuel (it looks like its only a couple inches away from the internal float resevoir.) I can't interpret the factory vacuum diagram for this part to see what it does exactly. I know when the car is running vacuum is provided to the diaphragm (line 8) pulling a plunger to seal off the carb thermovalve inlet from the canister. When the car is off vacuum is not there and the plunger is pushed via a spring in the other direction to block off a different passage in the carb.
My diaphragm had lots of holes so I plugged line 8 going to it with a ball bearing to stop the vacuum leak. My question is this: does the air-vent cutoff plunger need to be open when running or does it not make any difference to the engine operation. I could theoretically plug the thermovalve inlet line instead and remove the plunger to open the passage inside the carb. Should I?
BTW, I also found my canister purge control valve diaphragm doesn't hold vacuum, so I plugged that line as well (line 19) at the canister. So I assume the canister never gets purged now. Is that a correct assumption? Does it eventually build up and vent out the bottom hose or something?
Also my anti-afterburn control solonoid valve wouldn't hold a vacuum so I plugged that line as well. That should be fine, right?
Lastly, my hot air door actuator is shot so I temporarily plugged that line while I look for a replacement.
I've been hunting for a cause for the high idle on this car. I thought for sure all these leaky diaphragms were the cause. I also found and repaired a couple vac hose leaks. Still idling high even when warm. Lowest I can get it is around 1300 RPM. And it likes to climb.
Any ideas, anyone?
Thanks. Sorry about the long post.