my o3 ecotech keeps throwing an evap code saying that there is a small leak. i have the use of a tech 2 scan tool. i have tried the gas cap thing but thats not the problem. i have put the system under a vacuum and it shoes a little bit but not enough. there is no visible leaks under the car and no smell of fuel. Any suggestions or comments would be helpful.

I would probably suspect the purge valve - but that's just a guess. Times like this it's good to try to get your hands on any extra parts you can find, and just start swapping one by one.
If I could, I would probably try to get my hands on a complete evap canister assembly and replace the whole thing. Keep in mind that it could even be something as stupid as a pinhole rusted in part of the filler tube - I think these new systems are a little too sensitive to be practical. I'm not against emission controls or anything, but certain things can make it hard to keep a car on the road over the long term, without having to fix little stuff that isn't likely to have any environmental impact.
Sorry for the rant - but now you know where I would start. With such a small leak being detected, I wouldn't likely expect to smell any gas yet.
John

Mine is doin the same thing. EVAP Emissions leak....annoying....
Anyone else have any other ideas?

well i had that problem 2 days ago no idea what the problem is

Ive got 01 cavalier 2.2L, Ive got EVAP Emission malfuction, In which has been in the shop for 3 days, No performance issues at all the replaced the gas cap, I had to take my car to emmission testing I got a rejected status, I had to pull tooth & nail to get the fee waved. Too fustrating, I know I remember way back I could smell gas. Now nothing.

Good Luck.

I had a problem like this in my Beretta. Replaced the evap vacuum purge valve and it took care of the problem.


Dan Trump

2004 Cavalier LS Sport - Victory Red

thanks guys. i guess ill start by looking crap over with a magnifying glass.

Take it to Pepboys or similar shop and have them smoke test the evap system. If you are real unlucky, its a leak in the gasket on top of the tank where the pump-sending unit assembly goes in.

i work at a gm dealership and we got a smoke machine there. i just dont know if it works.

i doubt this will help, but it might take you down the right path. my sister's 04 cav had the same thing when she went for emissions testing. took it to the dealer where my mom works. i never hear what they said but her uneducated translation was that there was rusting or something in the filler neck that was causing a carbon build up in the emission system (?). didn't make a lot of sense to me but when they replaced the neck, the CEL went away and she passed emisions testing.

definitely get a smoke machine on it. small evap leaks are normally not something that's going to be easily visible and for what it would cost to just swap parts until it goes away, you're better off just getting it fixed right the first time. hooking up and running the smoke machine only takes about 10-15 minutes and that'll point out the leak so you know exactly what the issue is.