Unsolved EVAP 0442 Small Leak

[McGMT]

Well everyone, I am at a dead end. Keep getting a P0442 Small leak code on the TB. Here's the list of new parts.

Gas Cap
Vent Sol
Purge Sol


Now, today we smoked the system, for an hour an a half. Front port and fuel filler. No smoke... ANYWHERE... Opened the purge till it smoked, closed it , no smoke. Opened the vent till it smoked, closed it, no smoke. Checked the tank all over and the lines, no smoke. Checked the canister, no smoke. checked the lines in the engine compartment, no smoke.

ANY ideas? I have checked everything there is to check so I am now open to input from youns... Start throwin' words at me...

 

[McGMT]

Forgot to mention that there is a TSB about unexplained codes and such. Said to check n clean the PCM grounding... Another thing to add to the already done list.

 

[MAY03LT]

Did the smoke machine have the little ball that can detect leaks? If so, did it indicate a sealed system?
Does the FTP voltage change during seal/vent?

 

[McGMT]

Did the smoke machine have the little ball that can detect leaks? If so, did it indicate a sealed system?
Does the FTP voltage change during seal/vent?

Yes and yes...

We actually were able to hold the tank at around 9 inches of merc for a half hour with no leakdown. That was according to the FTP sensor and confirmed by das ball

 

[McGMT]

I just called chevy for the hell of it to see what they had to say. Didn't act like a dick or get loud or threaten anything just asked them if they have ever had this problem and all. To which they replied... "What is your preferred dealer? We are going to make you an appointment tomorrow and would like you to take the vehicle in." I told them what we had already done and such and that I do not want to pay dealer prices and such. She then says "This diagnosis and repair will be completely free of charge."

Isn't that something, a company that will stand behind a vehicle with 103k on the clock and a problem that cannot be solved.

I have an aftermarket warranty so even if I had to change something major I am covered, but GM is nice enough to just fix it. I will let youns know what happens when the stealership gets ahold of it. Shouldn't be a horrible experience as I used to work with the service manager there anyways.

 

[bore_pig]

Glad to hear they're helping you out. Let us know what it is. Sure sounds like you've covered all bases.

 

[McGMT]

The dealer I wanted is booked up pretty solid so my appointment is on Wednesday at 1:00 EST... So hopefully after that we will see whats going to happen with the poor girl.

 

[ksimm92]

"This diagnosis and repair will be completely free of charge."

ya don't hear that too often! good luck, hopefully they are able to find the problem.

 

[McGMT]

Well tomorrow at 1 we will see why I have a "small leak" that I cannot find, courtesy of GM. Let youns know whats up when I get back..

 

[McGMT]

As always, without a picture it didn't happen so here is a picture...
View attachment 23126

3 hours of smoke and pressure, fuel tank dropped down and all and no leak. Now I have to wait for GM to decide what to do next. But hey, at least it really has been free.

 

[ScarabEpic22]

Ive had a similar problem with my 02 TB, been fighting the P0442 code for years. Thought it was a cut in the Evap canister, so I removed it and epoxied where the hole could have been (I cut part of one of the mounts years ago). Issue was gone for 2+ years, but the code popped up again last winter when my brother had it in Bozeman, MT for the winter. Haven't been able to keep it from popping since.

Cant wait to hear what GM does for you, Id rather just remove all the Evap crap and kill the codes, sick and tired of fighting it.

 

[McGMT]

Ive had a similar problem with my 02 TB, been fighting the P0442 code for years. Thought it was a cut in the Evap canister, so I removed it and epoxied where the hole could have been (I cut part of one of the mounts years ago). Issue was gone for 2+ years, but the code popped up again last winter when my brother had it in Bozeman, MT for the winter. Haven't been able to keep it from popping since.

Cant wait to hear what GM does for you, Id rather just remove all the Evap crap and kill the codes, sick and tired of fighting it.

Have you ever tried having a local mechanic smoke your evap system? Its only around $30 and usually finds the leak easy. My problem is not common, actually I haven't ever heard of a EVAP leak nobody could find with smoke...

 

[xj2202009]

Glad they are assisting you,

I cleaned the purge valve by the tank, it had a lot of dirt. Cleaned the filter and that kept the code clear for about three days, but it came back again, where is the one in the front located?

 

[MAY03LT]

I cleaned the purge valve by the tank, it had a lot of dirt.

If you got dirt out of the vent valve the canister might breaking apart internally.

 

[McGMT]

If you got dirt out of the vent valve the canister might breaking apart internally.

I can agree with that, but that wouldn't show as a leak... That would, depending on where, probably either block a passage or just blow by. We are building pressure in the system and all , no smoke showing, but where the hell is the pressure going. Expecting a call tomorrow so I guess we will see what GM comes up with.

 

[BRomanJr]

I can agree with that, but that wouldn't show as a leak... That would, depending on where, probably either block a passage or just blow by. We are building pressure in the system and all , no smoke showing, but where the hell is the pressure going. Expecting a call tomorrow so I guess we will see what GM comes up with.

Flaky pressure sensor?

Could it be giving bad or intermittently bad feedback to the PCM?

 

[AtlWrk]

Flaky pressure sensor?

Could it be giving bad or intermittently bad feedback to the PCM?

Also, have you considered swapping the PCM itself to see if a second one reports the same fault?

 

[McGMT]

I don't have a second PCM, and I still havent heard back from GM or the dealer, if I don't hear anything by 3 I am gonna make a call....

 

[ScarabEpic22]

Have you ever tried having a local mechanic smoke your evap system? Its only around $30 and usually finds the leak easy. My problem is not common, actually I haven't ever heard of a EVAP leak nobody could find with smoke...

Nope, my 02 hasnt seen a dealer/mechanic in years. Firestone for new tires and alignment is all, I do everything else. For $30 Id be inclined to do it, bet in Seattle it's double that. Hourly rates are north of $100 here.

 

[McGMT]

Nope, my 02 hasnt seen a dealer/mechanic in years. Firestone for new tires and alignment is all, I do everything else. For $30 Id be inclined to do it, bet in Seattle it's double that. Hourly rates are north of $100 here.

Check around for a local mech that has a EVAP smoke tester and if he knows that you need a scantool capable of opening and closing the purge and vent valves. If all is kosher you should be able to finally put that code to rest.


AND GM just called me, they want to change out the pump to tank seal and see if that fixes the issue.. Of course they are doing it free especially as they cannot guarantee that it will fix it since it seems to be a mystery.

 

[ScarabEpic22]

Check around for a local mech that has a EVAP smoke tester and if he knows that you need a scantool capable of opening and closing the purge and vent valves. If all is kosher you should be able to finally put that code to rest.


AND GM just called me, they want to change out the pump to tank seal and see if that fixes the issue.. Of course they are doing it free especially as they cannot guarantee that it will fix it since it seems to be a mystery.

Will do that next monday, parents are taking the 02 for the weekend.

Glad to hear GM's doing something for you!

 

[McGMT]

Well now the pump module o-ring has been changed. New one is a different design with and inner and outer ridge on both sides instead of just a round o-ring.

The old ring had dirt marks across it as if the dirt had worked its way past the seal so it looked to me like it was leakin after all.

Only thing is that the top of the module is rusted like hell, the rest of the car is fine and there is hardly any surface rust anywhere under there but the top of the module is about done. Called GM again to let them know about that and see about the bulletin they had on the older ones but they said my vehicle isn't covered by that even though it falls within the requirements and that they pretty much don't believe me that it is rusted at all. I asked him if he would cover the vehicle when it burns to the ground he said he could not comment on that. Oh well.

We will see if the code comes back or not.

 

[xj2202009]

Well now the pump module o-ring has been changed. New one is a different design with and inner and outer ridge on both sides instead of just a round o-ring.

The old ring had dirt marks across it as if the dirt had worked its way past the seal so it looked to me like it was leakin after all.

Only thing is that the top of the module is rusted like hell, the rest of the car is fine and there is hardly any surface rust anywhere under there but the top of the module is about done. Called GM again to let them know about that and see about the bulletin they had on the older ones but they said my vehicle isn't covered by that even though it falls within the requirements and that they pretty much don't believe me that it is rusted at all. I asked him if he would cover the vehicle when it burns to the ground he said he could not comment on that. Oh well.

We will see if the code comes back or not.

I'm kind of growing fended of the light..damn thing, keeps coming off and on

 

[xj2202009]

don't have the time to mess with this, have a shop looking into it.