aarcr Posted May 18, 2013 Share Posted May 18, 2013 1992 F150, 302, 180,000 miles. Idles fine and runs well under load. Above idle to about half throttle is runs rough, it bucks. Give it more throttle it and smooths out till you get up to speed then if you are just giving it enough throttle to maintain speed it gets bucky again. Acts more like a fuel problem than a spark problem but I don't know that.Engine is in good condition burns no oil. What should I look for? Thanks! Quote Link to comment Share on other sites More sharing options...
YT90SC Posted May 18, 2013 Share Posted May 18, 2013 Sweep your throttle position sensor with a DVOM. IT should transition smoothly through its travel. I will bet that it has issues (dropouts or opens) in the lower range. Quote Link to comment Share on other sites More sharing options...
aarcr Posted May 18, 2013 Author Share Posted May 18, 2013 Sweep your throttle position sensor with a DVOM. IT should transition smoothly through its travel. I will bet that it has issues (dropouts or opens) in the lower range. I have not done this before. Are you saying the sensor should vary ohms in a smooth variation for 0 to some high value as the throttle position is moved from idle to wide open? Quote Link to comment Share on other sites More sharing options...
YT90SC Posted May 20, 2013 Share Posted May 20, 2013 YEs. It wont start out at 0, but yes. should transition smoothly from one end of the spectrum to the other. I cant recall right at this time which wire is which. IT is a three wire potentiometer. One is 5 volts in, one is signal return (basically a computer ground) and the other is the sensor's output wire. Cant remember which is which so if you get an unchanging value, move a wire to the other terminal. Quote Link to comment Share on other sites More sharing options...
aarcr Posted May 20, 2013 Author Share Posted May 20, 2013 YEs. It wont start out at 0, but yes. should transition smoothly from one end of the spectrum to the other. I cant recall right at this time which wire is which. IT is a three wire potentiometer. One is 5 volts in, one is signal return (basically a computer ground) and the other is the sensor's output wire. Cant remember which is which so if you get an unchanging value, move a wire to the other terminal. Thanks, I'll try that. Quote Link to comment Share on other sites More sharing options...
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