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1993 Ford Explorer California Emissions Cam synchronizer
My 1993 Explorer with the 4.0 OHV engine has been surging and just not running smoothly. I purchased a scope and ive been going through and testing each sensor. I have swapped out the pcm with 3 others. right now im down to the cam synchronizer. its a 3 wire hall sensor. i tested at the connector for 12 volts at the red wire, and ground at the black and all is good there. then i hooked my scope up to the signal wire and then to ground on the battery. i got a nice square wave but the voltage of the waveform is battery voltage just like the power wire. it is pulsing correctly but the voltage should be 5 volts shouldnt it? both my haynes manual and my otc EEC-IV manual both say it should be around 5 volts. what could be causing this to happen?
The following user(s) said Thank You: aboudi.naddaf
When it says key on engine off is supposed to be 11 volts, depending on the position of the sensor I get either 0v or 12 like it will be 0 and if I blip the starter it will show 12. My understanding is this is the sensor turning on and off so it should be normal but still curious. I almost want to purchase a sensor at the auto parts store (good friends with the manager) and just test it plugged in to just be sure. Then I can return it afterwards.
The following user(s) said Thank You: aboudi.naddaf
shaneGTO wrote: What does it say for the manual transmission under “hot idle” ?
Oh, that row of values is in dc volts average. An 11V peak to peak signal, that is a square wave, will appear to be 5V on a regular voltmeter if the signal spends roughly the same amount of time low as spends high. As the engine spins faster the signal will spend slightly more time high than low, hence the rise to 6.6V at 55 MPH. I hope that made sense, ScannerDanner explains this better.
The following user(s) said Thank You: aboudi.naddaf
Ok, when the engine is running it showing an average of 7 volts on my volt meter at idle and 14.6 volt peak on the scope. Would this still be ok regarding the book saying 11 volts?
The following user(s) said Thank You: aboudi.naddaf
Yes, I'm guessing charging voltage did not get accounted for in that chart for some reason, not sure, maybe the Ford guys tested that on a bench or something.
Edit: see footnote #5 in the bottom of chart
Last edit: 5 years 7 months ago by jreardon.
The following user(s) said Thank You: aboudi.naddaf
Ok, any ideas as to what could be causing my irregular idle? A few times I have to use clear flood mode to get it to start. And it surges at idle and has a slight stumble on acceleration. I can feel slight irregular pops out the exhaust . The engine has all new injectors and the heads were recently rebuilt. I’ve scoped every sensor I could think of, new O2 sensors the whole 9 yards. I ordered a nice OTC leak down tester and that should be here tomorrow and I’ll be doing a check on the valves. The misfire is not consistent like a mechanical failure would be. It has a new coil plugs and wires and the ignition control module has been tested as well. I’ve been trying to diagnose This car for over a year now... any wisdom is appreciated
Last edit: 5 years 7 months ago by shaneGTO.
The following user(s) said Thank You: aboudi.naddaf
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