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Can someone explain the purpose of the Air Switching Valve? The diagrams would indicate that it has something to do with engine temp. The vacuum hose has come off of mine. The location makes it almost impossible to reconnect. I believe this may be the cause of my high idle.
I removed the heater control valve, moved hoses, pipes, many wires etc. was able to use remote finger tool to put vac hose on. Still don't know what it is. Probably emissions and wish I could just pull all the emissions. Engine would be much easier to work on.
...Jimmy
I'm not familiar with 6.0 details. Does it have air injection? If so, my *guess* is that the air switching valve is a diverter valve to route output from the air pump. On older models, at least, output from the air injection pump is 'dumped' harmlessly into the air filter housing after xxx-coolant temperature is reached. When the engine is cold, the output is directed to the exhaust ports.
So it is just for emissions. I did notice the idle dropped slightly after putting the vac hose back on the Air Switching Valve. Not sure why it would make a difference. I had the Vac line plugged so it wasn't sucking air causing higher idle. I think I will start looking into Emissions removal. I'm sure there are threads on the forum discussing it.
Thanks...Jimmy
I think I will start looking into Emissions removal. I'm sure there are threads on the forum discussing it.
Yeah, research 6.0 specifics first before rippin'-and-tearin'. Some of the emissions stuff might be sorta integrated into the operation of the engine management system.
Hey - funny thing, I had to research this very same issue last night when I noticed both manifold ports exposed (open) on the driver side of my 5.3 v12. I failed to catch the issue before (the issue was left by the PO/former mechanic - the hoses were left off by mistake, I'm guessing, following some maintenance/repair job). Doug, as always (!), is correct - see attached pic from one of my Jag publications. Take care...
So for the first 45 sec it directs the cool air to the exhaust. The rest of the time it is directing air to the air cleaner which means it is doing nothing. So it is strictly for emissions. Evidently mine has been disabled (vac hose off) for years and not even noticed.
Sammy... Do you know where can I get one of those pubs for my 6.0?
Does the Marelli have a vacuum advance at all, Doug?
Greg
Not in the traditional sense. But the Marelli ECU does use a vacuum signal as part of the electronic timing adjustment.
The OP's 6.0 V12 might not even have a 45 second timer. I was simply pointing out that the 45 second timer, as shown in a prior post, is not part of the air injection control.
We really need to get emission system info that's specific to the 6.0, IMHO
Thanks jal1234, the document confirms that the air switching valve routes air to either the exhaust or the air filter depending on the 45 sec timer or 95 deg. engine temp. So it is only important to emissions. Good to know.
When I click on that link I get the info for 1992 model year, with the 5.3 V12....not 1994 model year with the 6.0
When I go to the 1994 documents, which cover the 6.0 V12, I cannot find any mention of the 45 second timer...but perhaps may have missed it
Cheers
DD
Oops, my bad.... You are absolutely correct. In fact, at the bottom of page 22 of the '94 guide, it says the 45 sec timer is replaced by control by the ECM. For some reason, I was thinking that the 6 liter started in 92.
Just a quick one. When I was figuring out the emissions plumbing on my 92 5.3L, the system was arranged so that when the valve diverted from the exhaust, it pumped air directly into the airbag, but bypassed the air filter!
Air Switching Valve?
