I have a quick question about my 2003 Disco with SAI. I am getting codes 1412 and 1415. I noticed that the corregated line was cracked so I replaced it. I also cleaned the SAI air filter. When I was doing all of this I took off the vacuum res and noticed that there was a substantial amount of oil in it. It doesn't seem quite right to me. Any ideas, comments, concerns? Thanks in advance

 

If the solenoid is bad the SAI valves will stick open and blowback from inside the valve covers will go backward through the entire system. The valves will begin sticking open when enough residue builds up inside them. Do you have the rumble sound of an exhaust leak at idle on the passenger side of the engine? Those SAI valves are supposed to close after the initial short cycle on a cold start. when they fail to close you get the blowback, with the solenoid failure you get the pump not stopping at the end of its cycle which eventually causes the pump to fail.

 

Unless my understanding is wrong, the SAI pumps into the exhaust, and does not come anywhere near oil? If the valves or selonoid stick open, it backflows exhaust through the system, but not oil?

Either way, it would end up in the pump and not the vacuum resivoir. The only way oil could get in there was either someone put it there, or it somehow flowed through the vacuum line. But that would seem really odd, being the vacuum is pulling from the resivoir, not to it.

 

Clean out the pump assembly and put it back together and you should be fine.

 

The SAI pump pushes hot air into the valve covers.

That would be why the pipes go there and that would be where oil would come from.

Check the RAVE for a diagram.

 

The SAI injects air into the exhaust ports of the cylinder heads to dilute the over rich fuel mixture during warmup, injecting hot air into the valve covers wouldn't accomplish anything.

Edit, I thought about the function of the SAI and realized I was mixing up the function of the EGR so I looked it up in RAVE, what it does is inject air into the exhaust ports to promote the burning of unburnt fuel during the warmup cycle, same general idea just a different approach, the EGR gasses prevent combustion but dilute the exhaust to lower NOX emissions by lowering the exhaust temperature and only happens under certain conditions. Both strategies are aimed at controlling emissions, just at different times.

 

I cleaned out the res and also pulled all of the vacuum lines for the SAI. The line that is on the right side of the vacuum unit was completely clogged with oil and sludge. I cleaned all of the lines and cleared the codes. I think that I found the culprit of the codes. I will find out in the morning when I start it and the SAI kicks on. Thanks for the help

 

I thought I might be wrong, as I have been more than once, so I looked it up. And here is what RAVE says:

The SAI pump is attached to a bracket at the rear RH side of the engine compartment and is fixed to the bracket by
three studs and nuts. The pump is electrically powered from a 12V battery supply via a dedicated relay and supplies
approximately 35kg/hr of air when the vehicle is at idle in Neutral/Park on a start from 20C (68F).
Air is drawn into the pump through vents in its front cover and is then passed through a foam filter to remove
particulates before air injection. The air is delivered to the exhaust manifold on each side of the engine through a
combination of plastic and metal pipes.