351w EFI 1993 f150 lobe idle and air pump
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351w EFI 1993 f150 lobe idle and air pump
1 My 1993 f150 when warm will always have a lobe idle when it is warm, i find it very annoying, no vacuum leaks or anything, i replaced the IAC a while a go with a newer napa one and it went away for a while. no cats, no muffler, no smog/air system.
2 My smog pump id like to remove, i just have the 2 ends connected, i wanted to get a new belt but heard something about the altinator would slip then?
2 My smog pump id like to remove, i just have the 2 ends connected, i wanted to get a new belt but heard something about the altinator would slip then?
Posting Guru
Joined: Sep 2008
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1 it isn't a lobe idle problem...I would bet you either have an exhaust leak or (and this I am guessing at) but could it be that your O2 sensors are not able to sample enough air with the mods you made to the exhaust? I have a small header gasket exhaust leak on my #5 and get the same thing you do. It is because the O2 sensor is off due to the leak.
2 you can remove the pump, either get a delete pulley and keep the same belt or get a belt that fits. You know it fits right because there is an indicator on the belt tensioner that indicates where the tensioner should sit with the belt installed. I have also done this, if you get a proper length belt, the alt won't slip
2 you can remove the pump, either get a delete pulley and keep the same belt or get a belt that fits. You know it fits right because there is an indicator on the belt tensioner that indicates where the tensioner should sit with the belt installed. I have also done this, if you get a proper length belt, the alt won't slip
Elder User
Joined: Feb 2014
Posts: 501
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From: Lincoln, NE
You can take the IAC off and clean it out to see if that makes a difference. I've also unplugged it to insure that something else is not causing the high idle speeds. Just don't adjust the throttle plate position screw.
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I know you can if you adjust the tps correctly from. 96 to. 98 volts
Lead Driver
Joined: Aug 2006
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From: Sand Lake, MI
Idle speed 100% computer controlled, that screw prevents the throttle plates from digging into the throttle body. The TPS itself was made to correspond to it not the other way around.
Closed Throttle can be anywhere between 0.6-1.0 volts.
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Fleet Owner
Joined: Oct 2005
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From: Kentucky
Throttle stop screw is and should be sealed in place, if so it hasn't been tampered with and there would never be any reason to do so.
Idle speed 100% computer controlled, that screw prevents the throttle plates from digging into the throttle body. The TPS itself was made to correspond to it not the other way around.
Closed Throttle can be anywhere between 0.6-1.0 volts.
It's an urban myth to adjust the throttle stop screw so the TPS voltage is closer to 1V at closed throttle.
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