3 replies to this topic

[tandem]

I am a nubie to the fourm and need help in the worst way. My 1996 960 non turbo has a problem in the secondary air system and sets code PO410.
I have verified that the blower runs when you would expect and that the SAS is opening and closing as expected. Plenty of air gets to the SAS output when the blower runs.

I found that the tube going from the SAS output to the head was almost totally clogged and cleaned that out.
The opening in the head was also clogged so I cleaned that as much as I could and reconnected the tube.

Wanting to make sure that everything was open now, I tried blowing air from my compressor into the tube (SAS on the bench, not on the tube). Only a very small volume of air at about 20 psi. would pass on into the engine/exaust. Ok, i thought, so maybe it has to be running. Tried that and still not much volume and a lot of back pressure. I know that the secondary air pump is rather high volume, low pressure, so I just can't imagine that air should not flow freely into the tube/head/engine.

With the engine running and nothing attached to the tube, there is almost no flow in or out of the tube.
Is this at all normal? if not how does one ever clean the passage within the head.

Any help will be most welcome.

[tandem]

I think...... it is fixed now. Found that clogging of the air passage is pretty common not just with Volvo but with BMW and others.
After 3 days of doing the following, I can finally get a reasonable flow of air:
Soaking with Seafoam, Chemtool, Breakfree, and electrical contact cleaner;
Probeing around with any tool/wire that I thought might open a passage without damaging anything;
Lots of compressed air;
Driving around with the SAS totally removed to allow exaust to hopefully blow out any gunk;
A couple of full throttle starts trying to increase the exaust pressure with the SAS still off.

So now there is a pretty good flow with compressed air, everything is back together, and I just have to wait for the drive cycle to complete.

[tandem]

Well, that didn't work. I never managed to get enough flow into the head to keep from setting code PO410.

Although it is otherwise a reasonably decent car, it has over 175K miles and is just not worth the major work needed to remove and dissamble the head in order to clean the passage from the bottom, I finally decided to just bypass the restriction. It basically came down to either finding a cheap fix or junking the car as it must pass emissions here.

I removed the heat shield from the exaust manifold and noticed that the 2 center bolts were very near to where I assume the factory ports end up. So, I drilled thru the bolt holes into the manifold and tapped them for 1/8 inch pipe nipples. I replaced the heat shield but used 2 1/8 X 2 inch pipe nipples in place of the 2 center bolts. I adapted these pipes with some flare fittings for 3/8 inch copper, and made a little plate with a tee to hook up the output of the SAS valve to my new ports with some 3/8 inch copper tube.
I also closed off pipe that had originally connected to the SAS with another little plate just in case there was still some leakage.

Two drive cycles later and finally all the monitors cleared.
It looks a little strange, but as far as I can tell, this works just as well as the original. The secondary air gets to the right place when needed and the computer is happy. I was a little concerned that exaust back pressure would be too much for the air pump to overcome, but it does not seem to be a problem.

Anyway, if you are fighting a secondary air problem check to be sure that the head passage is open in addition to checking the air pump and SAS valve functions.

[Three Fat Tigers]

Amazing. Thanks for the update.