ATP sensor readings question

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Old 02-19-04, 11:56 AM
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ATP sensor readings question

I have an 01 Dakota 3.9 4x4, wife has a 00 Rodeo 3.2 4x4, also have OBDII software and interface for my laptop.
When I look at sensor reading from the Dakota the ATP (absolute throttle position) is about 14.5% at idle and increases as throttle is applied. I notice on the Isuze while reading the MIL last night (damn Isuzu fuel level sensors) that the ATP on it was 0% at idle, and pretty much stayed there even with a throttle increase.
I just want to know if this is normal, I realize that comparing readings between 2 different vehicles is useless, and maybe the Isuzu doesn't provite the ATP data, either that or it has a problem, but I've not gotten a MIL for anything other than the fuel level sensor and the reduced EGR flow, I fixed the EGR issue, it's going to the dealer for a new fuel sending unit soon under the powertrain warranty.
 
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Old 02-19-04, 06:06 PM
mike from nj
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i'm sure you're well aware of the fact that you have no throttle cable on your isuzu. you have three APP sensors on the gas pedal, two TPS sensors on the throttle motor(throttle body) and they all read at different rates, so the computer can compare them and see if they all agree. (to see if they are varying at known rates). if you have a non-factory scan tool, i would think it would have no idea of which sensor to zoom in at to give you an indication of ATP.

blame GM for the fuel level sensor, 90% of your vehicle's electronics are made by general motors, including the pcm(computer). the egr valve is too. what i've found for an "egr insufficient flow" code is the valve is stuck or the tube is clogged directly behind the throttle body, or both.


for your dakota, the reading you are getting is an anomoly of your scan tool. it reads about .6 volts at idle, which is 0%, if it was higher, you would have a multitude of problems. stick a straight pin in to the tps connector on the signal wire and read it with a digital voltmeter, this is the true voltage reading. you can also do this on your isuzu at the throttle body, one would start low and go high, the other would be opposite(2 sensors there).



tell me more about this software, for your laptop. i'm curious.
 
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Old 02-23-04, 03:41 PM
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Mike, thanks for the in depth reply, and no, I wasn't aware the Isuzu had no throttle cable, I was aware there were vehicles without one, just didn't think it was one of them, so it makes sense about the reading. The software I'm using is here
http://www.obd-2.com/
You can download the software for free and view my recorded data if interested. I'm still trying to figure out everything it does, and these 2 vehicles are my first OBDII vehicles so there's a learning curve, but I've been working on vehicles since I was a teen (36 now). I prefere to do work myself rather than pay someone else that may or may not do a good job. I remember the days when working on vehicles was easy, I swapped out a motor and tranny in my 72 Gran Torino in a few hours!
 
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