Secondary Air

[Baconaire]

I am getting the no uncommon Secondary Air errors (P0410 and P1411) for a while now.

98 2.5 Box 5spd 75k miles, US car, daily driver run year round . Use Durametric ODB to read codes and reset CEL.

I have done the following:

-Replaced AOS and cleaned the throttle body and air plenum.

! problem persisted

-Did have a loose plug at one point but fixed that. (Changed all 6 plugs)

! problem persisted

-Replaced ALL of the secondary air components except for the hoses, and the pump. The pump works fine and I did clean the built in filter. The metal check valve that goes to the cylinder heads was very carbony. The change over valve looked ok but I replaced it anyway. Replaced the electronic change over valve, the vacum resivior and the plastic check valve that goes back to the intake. The hoses looked ok but I must admit confusion when trying to put it all back together. But I think I got it back correctly and noticed no problems with the hoses( no clogs or leaks). The pump sounds better and seems to run less but...

!problem persists!

- Had replaced the MAF 2 years ago (not becase of this) and cleaned it recently.

The CEL keeps coming back with the same 2 codes so it impacts both sides. Since the full replacement of eveything this past weekend I have reset the codes 3 times. The pump runs for a shorter time at startup. But it will occassionaly kick in 20 miles into a ride while at stop (engine at running temp of about 180ish) .

(Note:taking off the air plenum to access the sec air is a project, not for the faint of heart.)

Are there any other things I can look at? Could it be somehow related to the fuel tank and emission things there. I am never able to pump a full tank of gas. At all stations the nozzle clicks at about 7/8 of a tank.

I admit I don't fully understand why a vacum acuated valve is used and how it works in the sec air system. I do understand why the system exists and what it does, except for the vacum resivior. On our motorcycles we just remove similar emission systems and its no problem. But they also don't have a computer. Do Boxster racers remove such emissions items? I recently passed emissions test after reseting CEL.

Thoughts? Other things to check? Heeeeelp? This is killing me because the car runs fine.

Thanks all.

Edited August 8, 2007 by Baconaire

[wvicary]

The OBD system uses the O2 sensors the measure the secondary air system.... possible problem with the O2's. The air pump shouldn't be coming on with engine temps of 180.

[Baconaire]

Is there any way to test the O2 sensors? I'm know there's one on each side, pre cat, so its suprising that they would both fail. I see on the Durametric that the two sensors don't always agree, but I'm guessing that's a product of engine pulsing as the Durametric seems to sample every couple of seconds. They do sometimes agree and are within the operating range. Thanks.

Edited August 20, 2007 by Baconaire

[mikefocke]

You looked at this flowchart?

Here

[Baconaire]

I have, but since I was diggin in, I made it simple and replaced all the components, essentially addressing every eventuality the chart mentions. So the only option I have left within the sec air system iteself is operator error.

I suppose my bottom line question is what in the car decides I have secordary air problem in both banks? Is it the precat O2s. And if yes, would I not have other errors as well?

[insite]

I have, but since I was diggin in, I made it simple and replaced all the components, essentially addressing every eventuality the chart mentions. So the only option I have left within the sec air system iteself is operator error.

I suppose my bottom line question is what in the car decides I have secordary air problem in both banks? Is it the precat O2s. And if yes, would I not have other errors as well?

try replacing your gas cap.

[pomocanthus]

Baconaire,

Did you ever solve the problem? Your solution will help a lo of people with these persistent codes.

Thanks,

Hung

[djomlas]

try replacing your gas cap.

can that really be the problem? i noticed lately that every time i fill up i get a code soon after, 0446 i believe, and now i started getting these 2 that were discussing here...

[Loren]

try replacing your gas cap.

can that really be the problem? i noticed lately that every time i fill up i get a code soon after, 0446 i believe, and now i started getting these 2 that were discussing here...

P0446 EVAP Canister Shutoff Valve (Function) - Below Lower Limit

Possible causes:

- Purge air line blocked.

- Flow resistance of EVAP canister too high.

[insite]

try replacing your gas cap.

can that really be the problem? i noticed lately that every time i fill up i get a code soon after, 0446 i believe, and now i started getting these 2 that were discussing here...

worked for me. i noticed that sometimes it would come on after a fill-up, and go off about two days after other fill-ups. my theory is that the cap started to not seal so well, and that it would leak sometimes & trigger the CEL. i replaced the cap. the light went off after about 65 miles and never came back on. that was several months ago.

[djomlas]

sweet, thx man,

ive been meaning to go get the cap for a while now, just havent found the time