build issues

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Don H Jr
I made it to triple digits!
I made it to triple digits!
Posts: 103
Joined: January 12th, 2010, 1:11 pm
Vehicle Year: 1994
Vehicle Make: Jeep
Vehicle Model: Cherokee

Re: build issues: TPS WOT measures 3.7 volts at TPS

Post by Don H Jr »

Is this OK, or is TPS toasted. It goes up gradually from much less than one volt as you open the throttle slowly, the voltmeter rises to 3.7 at WOT. My book says should be, "just under 4.8 v".
Please give me your learned opinion on is mine toast at 3.7v? It's bucking and acting nutty under mild throttle pressure and cruise; with fine at WOT most the time. I just found the cracked coil and replaced it; but still have the TPS on my mind with that specific question of 3.7 vs. 4.8v.
I'm working out all the bugs on the tune and electrical before putting in a new stroker motor, so I can break it in right and progress rather than set myself back when I should be enjoying the glory of being stroked and broke.
Don Jr
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SilverXJ
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Posts: 5789
Joined: February 14th, 2008, 7:14 am
Stroker Displacement: 4.6L
Vehicle Year: 2000
Vehicle Make: Jeep
Vehicle Model: Cherokee
Location: Radford, Va

Re: build issues

Post by SilverXJ »

My 2000 FSM specs .26 volts closed, and 4.49 at WOT. Its a 2000, but I doubt it changed much. I'm really not sure what voltages are acceptable though.

What does the voltage do as you move the throttle through its range? Doe sit jump around between higher and lower volts ad you move it in one direction, or does it scale up nicely?
Don H Jr
I made it to triple digits!
I made it to triple digits!
Posts: 103
Joined: January 12th, 2010, 1:11 pm
Vehicle Year: 1994
Vehicle Make: Jeep
Vehicle Model: Cherokee

Re: build issues

Post by Don H Jr »

Silver XJ: It moves slowly from about three qtrs of a volt , moves evenly up to 3.7v. Just for the record, I recently read that your year XJ reads different for TPS check than mine: 1994. Yours is right on the money from what I read. Mine is the one in question at top voltage WOT being much less than the 4.8 or a bit less, but only 3.7v.
Another way to put it to anyone out there is,"With a WOT reading at the TPS on a 1994 XJ I6 Auto of only 3.7v, does this mean the TPS should be replaced?"
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SilverXJ
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Posts: 5789
Joined: February 14th, 2008, 7:14 am
Stroker Displacement: 4.6L
Vehicle Year: 2000
Vehicle Make: Jeep
Vehicle Model: Cherokee
Location: Radford, Va

Re: build issues

Post by SilverXJ »

This is from a 1995 XJ FSM:
With the ignition key in the ON position, check the TPS output voltage at the center terminal wire of the connector. Check this at idle (throttle plate closed) and at wide open throttle (WOT). At idle, TPS output voltage should must be greater than 200 millivolts. At wide open throttle, TPS output voltage must be less than 4.8 volts. The output voltage should increase gradually as the throttle plate is slowly opened from idle to WOT.
Same sensor as on an XJ. However it still doesn't say how much less than 4.8v. I don't think your TPS is faulty. The numbers aren't exact as different TPS modules will vary with they readings. The PCM adapts to those values.
Don H Jr
I made it to triple digits!
I made it to triple digits!
Posts: 103
Joined: January 12th, 2010, 1:11 pm
Vehicle Year: 1994
Vehicle Make: Jeep
Vehicle Model: Cherokee

Re: build issues

Post by Don H Jr »

Silver XJ Thanks for the info. I feel a bit better about mine now; but I did read just lately that the closed throttle voltage is different for yours and mine and yours and mine both fit the specks.

Don Jr
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