Mark: Hi it's Mark Bossert, producer of Pawlik Automotive Podcast here with Bernie Pawlik,
Pawlik Automotive, and we're talking cars.
How are you doing this morning Bernie?
Bernie: Doing very well.
Mark: So this week's victim is a 2003 Toyota Matrix that had an EVAP system problem.
What's an EVAP system and what was going on with this vehicle?
Bernie: Alright, well first of all the vehicle came in with a check engine light and it had
been at our shop previously several months ago with the same check engine light and the
same trouble code.
I'll talk about that in a minute but the EVAP system basically is a, it stands for evaporative
fuel system and what it does is it prevents gasoline vapours from escaping to the atmosphere.
Gasoline, if you've ever filled your gas tank up on a hot day you'll see all that vapour
kind of floating away, unless you're in the US with one of those gas pumps that keeps
the vapour contained.
Basically what happens is that gasoline is very volatile and it evaporates very easily
and that evaporated fuel is all hydrocarbons that creates smog and a lot of pollution.
It's a huge issue, you think oh it's just drifting away but it actually creates a lot
of issues so, not to mention it's actually your money that's actually floating away in
to the atmosphere so it's a good idea to keep the gas contained and that's what the EVAP
system does.
It's rather complicated, I mean it involves a gas tank, a sealed fuel filler, and a number
of pipes and valves and sometimes motors to keep the system contained but it allows the
air to be, as the gas is being sucked out of the tank of course it allows air to be
displaced but it doesn't allow air to go back, it doesn't allow the fumes to escape back
to the environment.
So that's basically what the EVAP system does.
It's pretty complex but you know it does its job.
Mark: So again what was going on with this Toyota Matrix?
Bernie: So no performance issue and that's pretty common with EVAP system codes.
The performance of the vehicle is often not affected, under certain circumstances it will
be but most of the time it doesn't really affect the performance it's just that the
system has picked up a fault that could cause gases to evaporate out into the air.
So I'll just get into some pictures right away here.
Here we've got...what do we have here?
Start, there's our 2003 Toyota Matrix, a little old but it's still in really good shape.
Look at the trouble codes.
So here's a scan on one of our scan tools that show the trouble codes.
P0440, there's a malfunction in the system and then a P0446.
The evaporative emission control system vent control malfunction.
So this is a little more specific of a code and you can see there's a current and history.
This is a way trouble codes are often stored.
They'll, depending on the scan tool, show what's actually there at the moment and what's
history so sometimes you'll only have a history code and not a current code.
Anyway that's a question for another time.
But what we found with this vehicle, because we'd actually done a previous diagnosis, and
actually I guess, I know we had another question of how difficult are EVAP systems to diagnosis
and I'll just jump right into that.
These can be really complicated and fiddly to diagnosis and what some of the reasons
why is that there are certain valves, there's a purge valve and a vent valve, and they'll
often malfunction intermittently so we can run through all the tests and we can test
it all and it all works fine, clear the codes send it away and then a week later the check
engine light is back on because the system malfunctioned.
So sometimes, you know we often rely on our data bases of what are common faults in these
vehicles.
One of the common issues that we ran, so last time we did the diagnosis we did the full
system test.
We tested for leaks, we found none.
We tested all the valves and controls.
Everything was working fine.
The gas cap was very old and a bad gas cap will cause some of these codes.
We replaced the gas cap and released the vehicle with the codes cleared and a few months later
the light comes back on again.
So without spending a lot of extra money of the clients to test everything that we have
already tested, we figured the best thing to do is to just go to the next most common
fault and that's the vacuum, the VSV valve on the canister purge tank.
That's an extremely common fault on this vehicle and it had never been changed, it was original
to the vehicle.
It's 180 thousand kilometres, 15 years old, so it made sense to change it at this point
in time.
Mark: So you have a picture of that?
Bernie: Yeah I do.
Yeah so that is the VSV, you can see it's a- that's the mounting bracket, extremely
rusty.
And where this unit mounts, right up here, this is the charcoal canister so this is a
big component of the EVAP system.
They've used charcoal canisters actually for a long time before they went to all this electronic,
sort of monitoring of the EVAP system.
This has been around since the late 60s, just to trap gasoline vapours but it wasn't quite
as sophisticated as is now.
But there's the location, that's the new valve installed.
There are various, as you can see the number of hoses that run to a number of different
locations and different parts of the vehicle.
Hoses that run to engine, hoses that run from the gas tank, hoses that go to the fuel filler
neck, they're all over the place.
Anyone of these hoses can leak so when we do testing on the system we all test, you
know to find out whether there's leaks anywhere in any of these components.
And that ends our picture show.
Mark: So what happened next?
Bernie: What happened next?
We replaced the valve, cleared the codes, and so far it's working fine.
Now again as mention, this was one of these repairs where we'd already done all our testing
and we couldn't find a problem, so we've replaced a couple components, so we'll see how things
go.
It's not the way we normally like to do things in our shop.
We really like to test and find things that are wrong but often, as I said with these
valves like that VSV valve, they can malfunction intermittently.
They'll be, you know you test it and you power it up manually and it works fine, works fine,
works fine and then, you know, a hour later something will happen and it won't work.
So a lot of times if it's a known common fault on a vehicle it's a good idea to replace that
just to put it aside.
Leaks are a good thing, you know leaks are a pretty solid thing to test.
We can see them, we can verify that pressure's dropping and in this case it wasn't so, an
electronic valve like that is a good call.
Mark: So for troubleshooting it's really important that you gather as much information as possible
before you jump to what might seem like the obvious conclusion but often isn't.
Is that fair?
Bernie: Exactly.
Yeah exactly.
Mark: And how are these Toyota Matrix for reliability?
Bernie: They're good.
Yeah I mean they're awesome car.
Very little goes wrong, even these EVAP systems are very reliable.
You know if you're living, by the way EVAP system faults happen a lot more if you live
in a climate with a lot of salty road because it tends to corrode things and wear things
our a lot faster.
But yeah really reliable vehicle.
Mark: So there you go, if you want experts in diagnosis and troubleshooting to look after
your vehicle the guys to call are Pawlik Automotive.
You can reach them at 604-327-7112 if you're in the Vancouver area.
You have to call ahead to book because they're busy.
Check our their website, pawlikautomotive.com; YouTube channel, Pawlik Auto Repair.
Thank you very much for listening on iTunes, we appreciate it.
Thanks Bernie.
Bernie: Yeah thanks for watching and thank you Mark.