Evap emissions and a mysterious black box, haynes has no idea what this thing is Options

[enderswift]

hey 6gc,

I have a question for your collective hive mind of wisdom. I'm trying to diagnose an evap emissions code and cant figure out what this wierd black box is behind my fuel tank. Haynes is useless since it doesn't even show it anywhere in the fuel system diagrams. I'm really stumped by this!

here are the pics:



its located in the space between the fuel tank and the spare tire well




it has a bunch of what look like solenoids connected to it. not only that it seems as though the fuel send and return lines are involved as well, but im not sure as i havent dropped the tank

anyone know what this is? what it does? and how it can break/influence evap codes?

[enderswift]

thanks for the responses guys,

I looked into it and it turns out that 98-99 celicas share the same updated evap system as the 5sfe camry's. So a quick search for camry evap issues shed light on all the things that junk haynes manual wouldn't cover.

heres the break down for those who may run into the same issue in the future:

the 98-99 celicas have a large rectangular charcoal canister located in the rear of the car - right between the gas tank and spare wheel well -
attached to this tank are two cylindrical valves which are controlled by the vsv (vacuum solenoid valve) which is also in the rear of the car (keep in mind that our cars have two vsv's, one in the front for the egr and one in the back for the evap). The vsv is the main vacuum junction that controls when the charcoal canister draws fumes from the tank and when it sends those fumes to the intake manifold via those two cylindrical valves i mentioned. Apparently, the design of the vsv causes it to fail quite often and the fact that its located right underneath the car means its exposed to some harsh conditions that expedite the failure.

when the thing breaks (as it inevitably does) it will trip one of two codes which may or may not cause an intermittent check engine light.

The first code is P0441 which says there is a flow fault. this code could mean any number of things ranging from loose gas cap to leaks in the lines, or even a cracked charcoal canister. AKA this code doesn't tell you jack sh*t other than something is broken with the evap.

the other more telling code is P0446 evap circuit fault. This one points directly at the VSV or any connections leading up to it. *keep in mind that a bad vsv can trigger either code or both at the same time (intermittently), which makes diagnosing the exact issue a little problematic. obd II ftw...

so how to solve the issue? well if you have a basic understanding of how a solenoid works you will understand that the steel plunger within the coil can get stuck from corrosion, keeping it from moving. This is when the vsv is stuck open or closed thus causing the cel. A good rule of thumb with solenoids is that a good whack can temporarily free up the shaft until a replacement can be installed.

thats exactly what i did. first i connected a 12 source to the vsv to see if it would click. it didn't. so i took a screw driver and a hammer and whacked the bracket that was holding the solenoid. When i reconnected the power it clicked just fine. The check engine light hasn't come on since

hope this helps someone in the future

oh and one more thing.
<-----what the hell does a guy have to do to get a third square around here? im not about to turn into a spam whore but god damn its been forever haha

This post has been edited by enderswift: Mar 27, 2010 - 7:14 PM

[DIONYZUZ]

thanks for the responses guys,

I looked into it and it turns out that 98-99 celicas share the same updated evap system as the 5sfe camry's. So a quick search for camry evap issues shed light on all the things that junk haynes manual wouldn't cover.

heres the break down for those who may run into the same issue in the future:

the 98-99 celicas have a large rectangular charcoal canister located in the rear of the car - right between the gas tank and spare wheel well -
attached to this tank are two cylindrical valves which are controlled by the vsv (vacuum solenoid valve) which is also in the rear of the car (keep in mind that our cars have two vsv's, one in the front for the egr and one in the back for the evap). The vsv is the main vacuum junction that controls when the charcoal canister draws fumes from the tank and when it sends those fumes to the intake manifold via those two cylindrical valves i mentioned. Apparently, the design of the vsv causes it to fail quite often and the fact that its located right underneath the car means its exposed to some harsh conditions that expedite the failure.

when the thing breaks (as it inevitably does) it will trip one of two codes which may or may not cause an intermittent check engine light.

The first code is P0441 which says there is a flow fault. this code could mean any number of things ranging from loose gas cap to leaks in the lines, or even a cracked charcoal canister. AKA this code doesn't tell you jack sh*t other than something is broken with the evap.

the other more telling code is P0446 evap circuit fault. This one points directly at the VSV or any connections leading up to it. *keep in mind that a bad vsv can trigger either code or both at the same time (intermittently), which makes diagnosing the exact issue a little problematic. obd II ftw...

so how to solve the issue? well if you have a basic understanding of how a solenoid works you will understand that the steel plunger within the coil can get stuck from corrosion, keeping it from moving. This is when the vsv is stuck open or closed thus causing the cel. A good rule of thumb with solenoids is that a good whack can temporarily free up the shaft until a replacement can be installed.

thats exactly what i did. first i connected a 12 source to the vsv to see if it would click. it didn't. so i took a screw driver and a hammer and whacked the bracket that was holding the solenoid. When i reconnected the power it clicked just fine. The check engine light hasn't come on since

hope this helps someone in the future

oh and one more thing.
<-----what the hell does a guy have to do to get a third square around here? im not about to turn into a spam whore but god damn its been forever haha

Did you have to remove anything to get the canister out? I was able to disconnect everything but the wiring harnesses because I couldn't fit my hand in the small space to get to it. I am stuck with the p0446 code right now and I need to pass emissions by the end of this month.

IMG_1856[1]
I circled the trouble spot.