Hey everybody, I recently got a 1996 Avalon XL and the check engine light popped up with the codes P0401 and P0446. After cleaning the EGR valve and changing the PCV valve everything was back to normal for a couple hours. Then the CEL light pops up again only throwing the 5 codes from above, a bit of research shows that this is probably a vacuum leak but I'm having a hard time identifying it. So at this point I've noticed several things, the PCV valve doesn't go all the way in, there's this which I can't seem to find a hose that goes with it... http://picasaweb.google.com/lh/photo...eat=directlink http://picasaweb.google.com/lh/photo...eat=directlink
and then what's more is I didn't replace the gaskets. So am I right in assuming it's a vacuum leak and if so is it something that using soap would be able to identify?
Last edited by thelamacmdr; 08-26-2010 at 02:09 PM.
Hey everybody, I recently got a 1996 Avalon XL and the check engine light popped up with the codes P0401 and P0446. After cleaning the EGR valve and changing the PCV valve everything was back to normal for a couple hours. Then the CEL light pops up again only throwing the 5 codes from above, a bit of research shows that this is probably a vacuum leak but I'm having a hard time identifying it. So at this point I've noticed several things, the PCV valve doesn't go all the way in, there's this which I can't seem to find a hose that goes with it... http://picasaweb.google.com/lh/photo...eat=directlink http://picasaweb.google.com/lh/photo...eat=directlink
and then what's more is I didn't replace the gaskets. So am I right in assuming it's a vacuum leak and if so is it something that using soap would be able to identify?
Try to find the dangling vacume line. Sometimes it can be hard to see, but it will be there. Plug that in, clear your codes and you should be ok. Soap is an ok option. You can also use your ears or a stethescope. You will hear a lound hissing or sucking noise where your vacume leak is.
For the PCV valve, did you install a new rubber grommet with it? Install the grommet, then the PCV valve. She will slide in. You could always gently lube the inside of the grommet with a small amount of oil to help the PCV valve slide into place.
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yeah I'm pretty sure I did but I didn't buy a new grommet and there's still wiggle room. Also, would the PCV be affected by using carb cleaner to test whether the idle changes?
Carb cleaner is what I would use to find the leak. That is if you cant simply find a broken or disconnected hose. If it is not your PCV being loose, use the carb cleaner and go around the engine bay slowly moving spraying the hoses. You should be able to identify a bad hose this way.
well don't i look like a fool, I guess I disconnected it while trying to remove the bolt from the valve >_< live and learn.... thanks a lot
EDIT: I still hear the hissing sound, that hose might have fixed one problem but it sounds like there's another somewhere. Might just be me though...
No problem,
Vacume lines are my nemisis. They are small, black and can easily dissapear in the shadows of the engine bay!
The PCV will not be effected by carb cleaner. The PCV is just a one way valve that lets the positive crank case pressure vent back into the intake. If anything you can clean the PCV Valve with a bit of carb cleaner when the engine is running. Shoot it into the intake manifold via a vacume line, or pull the PCV valve and clean it out.
If you have wiggle room replace the grommet. They get old and brittle. They only cost a few dollars. BE VERY CAREFULL when removing it! They have a tendency to break and get stuck. A new grommet will ensure a tight and proper seal.
I'm not sure what I did but the hiss is gone now and the only problem left is to solve that pesky p0401 that everyone seems to get >_<. Thanks for all your help
well, the p0401 came back today...I tried skipping the VSV altogether and connecting the modulator directly to the EGR valve..Also I noticed the filter above the modulator was really dirty so I replaced that. I think at this point the vacuum modulator is the issue as far as I can tell but I can't tell if it's the modulator itself or if it was the filter that was causing it. Any ideas? I tried all the other suggestions in other threads which is why I'm asking here.
remove the negative battery terminal. hold the brake pedal down for a minute. reconnect and the computer will boot from rom, "forgetting" everything it "knew" - including the trouble code you had. if the filter fixed it, the code will not come back.
else you might try removing the egr valve and cleaning it and it's passages with some... brake cleaner! that stuff really does the trick.
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It worked fine until I fixed it! 
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