To add onto that, are we talking about the purge valve that’s attached to the intake hose that leads to the tb?
The purge valve is usually somewhere in the evap pathway from the canister to the throttle body. Where exactly it is located varies vehicle to vehicle. On my older Corolla it is in the area where the engine meets up w/the transmission.
Fairly easy diy’er job on my older Corolla, but no idea how difficult it is on your car.
Is there anyway to test this valve?
It passes gasoline fumes in use, but the function of that part is usually the same as an electric-operated air-switch. There are two ports that have tubes connected. Do you see the two port connections? Don’t mistake these ports for its electrical control wires. When programmed open, air will pass through from the input port to the output port, closed, air won’t pass. Shops would test it with a pro scan tool which has a utility that can open and close it at will. I diy’er test the one on my Corolla using a vacuum pump to see if air moves through it.
If you think it’s giving the rough idle (possible but not too common), then just find where it feeds to the throttle body. Pull that connection and stick a vacuum cap on it. That will isolate the evap system from the engine.
Disconnect the electrical connector and the line coming from the canister. With the engine running, put your finger over the now-open port. If you feel any vacuum, the valve is leaking and needs to be replaced.
Okay, I’m going out on a limb here and this might sound stupid. But it’s been consistent. The car is idling fine at night it’s running very well but during the day it’s idling bad and it doesn’t make sense to me but it’s definitely true it’s been that way for the past 4 weeks or so just didn’t wanna say anything until I made sure
Does the idle quality change by turning the headlights on and off?
No I just tried it
The car’s computer increases the idle rpm to prevent poor idle and stalling for various reasons. For example if you turn the steering wheel, or if the engine fan turns on, or if there’s a bigger than normal draw on the alternator. Turning the headlights on produces a bigger alternator draw, so that’s why I asked. But if that’s the reason, it must be hidden by something else during the day.
What could it be if the idle is better at night
Maybe the next experiment is to try switching off the headlights when it seems to be idling well at night. When safe to do so of course. Does switching them off cause a rougher idle? You mighttry the other things that affect idle rpm
- turning steering wheel
- turning on A/C
- turning on rear window heater
- when engine compartment fan turns on/off
- hvac blower motor on/off and various speeds
- in Park vs in Drive (with brakes applied)
- whatever else you can think of that’s safe to do
The cars fan makes the idle jump when it turns on, when i turn on the A/C the idle gets worse, its better in park, but a lot worse in drive