P0442 - Evap System Slow Leak

Hello,

I have a 1998 Volvo v90 (135k miles) with a re-occuring Code P0442. I have borrowed a smoke pump and traced the source of the leak to a hose located near the driver side firewall and shock tower, connected through a solenoid type valve (is this the purge valve?) to another hose which goes down in a round hole in the frame/subframe.
I dont know if this is valve suppose to be opening or closing but I can feel vacuum at the end of the open-end hose and I can feel the valve clicking when I unplug the connector.
Does anyone know where is this hose's function is and why it is not connected to anything besides the valve?
I have no diagram or functionality of the valve and/or replacement data.
Any help is greatly appreciated.
Thank you in advance!

DanV90

Sounds like it's the vent valve. If so, the reason you have smoke exiting the vent valve is that it's a normally open valve. The PCM activates the vent valve to close it and test the integrity of the system. To properly smoke test the EVAP system you need a scan tool that will close the vent valve. Then smoke test. (The purge valveis a normally closed valve)

Thank you Darkrooms!
It seems to me that if the valve is a "normal closed" then smoke should not be comming out if the car is not running or if ingnition is off.
also, I will check the valve to see if it is operational. BTW, do you know who sells this type of valve, just in case?
Thank you ver much, I appreciate your advice.

DanV90

no,no,no, you misunderstood. The vent valve is a normally open valve. It's going to have a hose going to it and none going out of it. THe purge valveis a normally closed valve. It's going to have a hose going to it and away from it. I think the valve you're talking about is the vent, which is normally open, and that's why you have smoke exiting it. Activate it to close it, then retest

Hello Darkroom, thank you again for your reply !

I am sure it is not the purge valve, as you mentioned it. I have seen picture of a purge valve and this is diferent.
From your explanation I am now certain that it is the vent valve. I will have to activate (close) it and then run the smoker through it and see if there are any leaks. When I unplug/plug (energize) this valve I can feel it click so I think it is working.
Also, after about a minute or so (with the engine running) I can feel some vacuum pulsation. Is this normal? And where is this coming from, what creates this pulsation. Is there a pump or just the effect of the valve closing?
I had checked AllData and it does not show anything like an open air vent valve or a pump. The things it shows are the purge valve between the canister and the intake manifold, and a rollover valve between the tank and the canister. Could that be it? I am not so shure beause it is not open to air. I am soooo confused!
I have already changed the fuel tank cap and two crappy hose elbows and tomorrow I will try to re-smoke the system.
I will let you know the outcome, but in the meantime, again, thank you!

Dan V90

The diagram may not show it, but it's there. Its not the rollover valve, that's for in case of a rollover in an accident, gas won't exit the tank. The pulsation you feel is probably the LDP pump. It uses vacuum from the engine to operate the pump, and the pulsation is normal. The fact that the vent valve clicks isn't conclusive. Activate it manually, if you have to using your own supplied power and ground, and recheck for smoke. It's a simple solenoid, open/close valve and you won't hurt it as long as you supply power and ground to the proper terminal.

Well..., later is better than never! I have traced the small leak (code P0442) to the Purge Valve by testing the valve with a vacuum pump.
After that I had a re-occurring code P0455 (Evap System Gross Vacuum Leak).
I used a vacuum pump and traced the problem to the back of the car, on top of the fuel tank.
I had to flip over the back seat, remove the 3 nuts that hold the floor panel down and flipped it over.
Under the panel on the driver side is a 10" x 8" access plate, which is secured by four bolts. By removing them you get access to the top of the fuel tank, so if you ever need to replace your fuel pump that is the way to do it.
After removing the access plate I run the smoke pump again and traced the smoke to a vacuum line connected to a white squareish plastic valve (probably the rollover safety valve).
The vacuum hose is slightly curved and of unequal diameter, one end is about 1/4" ID and the other end is about 3/8" ID (maybe sizes are in millimeters).
The crack was right at the curvature, and with no smoke pump would have been almost impossible to locate and fix the problem. There is no way to trace or access this from under the car.
In conclusion, if I will have to do it again it is a job that takes no more than 45 minutes (a total of seven bolts/nuts with a # 10 mm socket wrench). Easy job if you know what to do but I had no direction of how to start and Alldata does not have anything about it.

I know this is an earful but I hope this may save somebody some time, money and aggravation.
As for the code problems, so far so good. Happy motoring!

DanV90