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I have a 1995 Ford ranger that idles rough/fast (1400-1200 RPM until it gets rough and nearly dies). I was playing around with a borrowed scangauge II (it’s OBD2 despite being a ’95) and noticed that my TPS wasn’t reading right… 17% at idle, 90% full throttle (I checked and no it’s not a floormat under the pedal issue).
It also has EGR issues that so far seem fixed but the vehicle hasn’t been driven much (ABS issues and a dead tranny)… for that I threw on some JY parts (DPFE sensor and EGR valve+ new gasket) the previous owner included (leftovers from an engine replacement).
Are my readings cause for concern and if so, what’s the best way to check the TPS?
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what you’re really looking for on a tps is erratic readings. When a car comes into my shop with a TPS code, that’s the first thing I check. Hook up a scan tool that does live data, pull up the TPS on a graph, slowly push down on the peddle and slow let off, it should be a steady climb up the hill and back down. If you do this and it starts going up and then divits down even for a second and then continues on its right path then the TPS is bad. Most of the time, not all the time, you’re looking for dips in the hill as the pedal goes up and comes back down.
You won’t always get a 0-100% reading. Close, but rarely dead on. That said you alluded to an engine replacement at some point. Perhaps someone got the throttle cable too tight. You might try moving the throttle linkage by hand to see if you can get the throttle to close. If you can and the idle changes, I’d adjust the throttle cable to spec. More info on idle issues here.
http://www.ericthecarguy.com/faq/solving-automotive-idle-problems
Good luck and keep us posted.
Will do next week… it’s off at the tranny shop getting a rebuild right now.
Yes the previous owner put in a used motor when he bought it 3000 mi ago… other than the idle issue, seeping oil at the valve cover and oil pan gaskets, seeping coolant at one of the water pump gaskets, and the oil pan being rusty and slightly dented, the engine seems to be in good shape (115K on it).
I wouldn’t worry about it, until it becomes a problem. As eric said I would check the linkage and see if it needs to be adjusted. Over time the cables with stretch, or if they were over tightened to begin with that would obviously cause a problem. Keep us posted after you get a chance to play with it.
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