High Idle/Smog Pump
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Freshman User
Joined: Sep 2007
Posts: 39
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From: Salt Lake City, UT
High Idle/Smog Pump
So my brothers bronco starts up ok, and idles at around 1k cold but as soon as the smog pump kicks on it goes up to about 2k and the inlet hose for the pump is blowing out hot air... 
what do you think?
what do you think?
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
Fleet Mechanic
Joined: Mar 2005
Posts: 1,603
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From: St Louis
Are you sure you are on the inlet to the smog pump? Also, smog pumps are constanly running there are no clutches in them until the bearings lock up then they are constantly off. The Smog pump has a air dump muffler on top of the inlet muffler during warm up of the motor. Are you talking about the A/C clutch kicking in?
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Freshman User
Joined: Sep 2007
Posts: 39
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From: Salt Lake City, UT
Its definitely not the a/c clutch. It will be idling fine, and then you hear what sounds like a vacuum leak from the pass. side. There is a hose that comes up off of the smog pump that should be plugged into the silencer or whatever you want to call that thing, but someone has cut it (we just barely received this bronco 2 days ago.) and it lays next to the canister. You can feel quite a bit of hot air being pushed out the hose. Unless this hose is supposed to go somewhere else. Yeah we will pull codes as soon as we can.
Makes me appreciate the old '64 all the more.
Makes me appreciate the old '64 all the more.
Fleet Mechanic
Joined: Mar 2005
Posts: 1,603
Likes: 1
From: St Louis
The smog pump had several styles used on routing the air around in the engine. When you compress air or force it it will warm up because it has energy applied to it so yes the air coming from the pump will be warm. At engine start up with a cold motor the smog pump dumps to the atmosphere, short time later or when you take off with a cold motor the air is routed to the exhaust air diverter valve, on a warm engine the air is routed to the cat/exhaust pipe on a cold engine it is routed to the heads. I am not entirely sure the haynes manual has the A.I.R. routing diagram, but there are diagrams available. Also, vacuum leaks are the biggest cause to high idle conditions on these engines.
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