throttle body - basic settings
03-05-2002, 06:41 AM
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throttle body - basic settings
1984 4.7l 16v auto, twin dizzie, euro, RHD. no cats, no oxygen sensors.LH Jetronic (hot wire)
in my further quest to persuade my errant vehicle to run, i have stripped out all of the injection and inlet tract.
having found a miscellaneous collection of dropped washers, small hex nuts, what seems like several gallons of yuk, and other sundry lost items in the 'vee' i have now continued on to the actual component parts.
the throttle body has suffered from PO tweakitus. to the extent that the throttle does not operate the idle switch even with the switch fully rotated on its adjustment. the throttle valve stop bolt has been screwed out too far. you could drive a double decker bus thro the current butterfly/bore clearance.
what is the correct mechanical clearance for the butterfly to bore when throttle is in the idle position?
regards
johnb
in my further quest to persuade my errant vehicle to run, i have stripped out all of the injection and inlet tract.
having found a miscellaneous collection of dropped washers, small hex nuts, what seems like several gallons of yuk, and other sundry lost items in the 'vee' i have now continued on to the actual component parts.
the throttle body has suffered from PO tweakitus. to the extent that the throttle does not operate the idle switch even with the switch fully rotated on its adjustment. the throttle valve stop bolt has been screwed out too far. you could drive a double decker bus thro the current butterfly/bore clearance.
what is the correct mechanical clearance for the butterfly to bore when throttle is in the idle position?
regards
johnb
03-05-2002, 09:32 AM
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The idle is basically controlled by the auxillary air valve, so the throttle plate is pretty close to being closed. No spec that I remember.
03-05-2002, 10:24 AM
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John,
On other vehicles with LH, the throttle plate is SHUT, and idle is controlled by a screw adjusted bypass channel, and an idle speed control mechanism (stepper motor on LR).
jp
On other vehicles with LH, the throttle plate is SHUT, and idle is controlled by a screw adjusted bypass channel, and an idle speed control mechanism (stepper motor on LR).
jp
03-05-2002, 10:40 AM
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hi
if the throttle plate is supposed to be closed, why is there an adjustment for it.....why not just let it settle on the throttle body bore?
previous cars i have owned have always had a basic throttle plate to bore clearance, final idle being set by air bypass screw......... although this is my first hot wire car. others have all been flappers.
johnb
if the throttle plate is supposed to be closed, why is there an adjustment for it.....why not just let it settle on the throttle body bore?
previous cars i have owned have always had a basic throttle plate to bore clearance, final idle being set by air bypass screw......... although this is my first hot wire car. others have all been flappers.
johnb
03-05-2002, 11:11 AM
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I think if the throttle closes completely, it can stick in the bore. I noticed my 944 throttlebody would do this. Not like it would stick so you couldn't open it, but enough to be felt and bring the consistency of the throttle plate's resting position into question. So I think the adjustment is to get the throttle plate to close as much as possible without binding in the bore.
I'd close the throttle plate as much as possible. If you can close it all the way without it snagging in the bore, great. If you do feel it catching in the bore, adjust it more open until the roughness you feel when it catches just goes away. You should be able to bring the idle/full throttle switch into adjustment at this point.
You'll probaby have to open up the air bypass a bit to get the car to run again after closing the throttle plate.
Let us know how it goes.
Bryan
I'd close the throttle plate as much as possible. If you can close it all the way without it snagging in the bore, great. If you do feel it catching in the bore, adjust it more open until the roughness you feel when it catches just goes away. You should be able to bring the idle/full throttle switch into adjustment at this point.
You'll probaby have to open up the air bypass a bit to get the car to run again after closing the throttle plate.
Let us know how it goes.
Bryan
