How to test and repair your EVAP valve:

Post by **songzunhuang** » 15 Mar 2015, 14:43

Well for my car, this was not the issue. I tried to repair the valve and couldn't tell if it really worked. I was still getting the code. So I bought a new valve. That didn't remedy the code either. So the search continues for me.

Post by **cn90** » 01 Nov 2015, 09:24

In the original post by "thecheat" (the original poster), he mentioned that you apply 12V then check the vacuum. I don't think this is true.

The way I understand is:
- Engine OFF, the valve closes, you can't blow through it.
- Once the 12V is applied, the valve opens, allowing gasoline vapor to enter the intake manifold.

So, if I am right, then the way to check the valve is:
- Take it out of the car and blow through it, if you can, it is stuck in the OPEN position.
- Now if it is tight (you can't blow through it), then apply 12V, you should now be able to blow through it.

How do I know?
- My 3-yr-old Bosch valve is kaput.
- I have a brand-new Pierburg valve and I compared the new Pierburg vs the kaput Bosch, and these are my observations.

Sommerfeldt · Post by **Sommerfeldt** » 01 Nov 2015, 10:45

Or just leave it in the car, pull hoses, put clean hose on one end, and blow through.

Though, are you saying, then, that the valve is continuously open when the car is running?

- S

Post by **cn90** » 01 Nov 2015, 10:51

When engine runs, the valve opens for short period of time during startup and that is it.

oldschoolvolvo · Post by **oldschoolvolvo** » 23 Dec 2023, 06:38

what is the expected resistance across the terminals for the EVAP valve?

Post by **abscate** » 24 Dec 2023, 05:48

oldschoolvolvo wrote: ↑23 Dec 2023, 06:38 what is the expected resistance across the terminals for the EVAP valve?

Depends on part number, year model etc

For the ME7 square type purge valve it’s 27 Ohms but no tolerance is given.

I’ll fact check that , too.

Fact check 29.7 +- 1.4 ohms

I’ve found many cars run fine without ECM codes outside this range, so it isn’t a good diagnostic for definitive failure. It’s a duty cycle controlled valve , not an open/ closed valve , btw.

The first first in this thread might be correct for the referenced BMW m30 but is not correct for P80s Volvo series purge valves.

oldschoolvolvo · Post by **oldschoolvolvo** » 24 Dec 2023, 08:25

thanks I was thinking of the P80 cars
is ~27 ohms still a good number?

How to test and repair your EVAP valve:

Re: How to test and repair your EVAP valve: (2023, contains wrong info)