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Normal TPS sensor reading?

spoulson

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Feb 5, 2003
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Middletown, DE
I think I found the problem with my overactive idle on my car. It wants to idle around 2.5k on startup and then settle around 2k when warmed up.

I just got a Palm VIIx with Palm'n'Stein installed. It says my TPS is reading 9 or 10 at idle. I blip the throttle and it goes up and settles again at 9 or 10. I played with the throttle body. If I tried to force the TB closed against the stop, the idle would then settle down to around 750 or so where it's supposed ot be. But as soon as I let go, it's back up at 2k.

Is this a faulty TPS or should I need to adjust it? If so, how?
 

Turbo4door1

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Feb 20, 2003
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Kearneysville, WV
I just put new throttle shaft seals in and adjusted my TPS tonight. I used this site to do it: http://www.plymouthlaser.com/tps.htm I haven't driven the car anywhere yet, but seems to be good. That thing is VERY sensitive. Just the slightest movement, and it chages a good bit. There is also a way to do it with the voltage when the key is on, but I don't remember the specs for it.
 

spoulson

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Middletown, DE
Cool! I will have to use that to check my adjustments.
 

spoulson

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I think I've found my problem. For some reason the accelerator cable between the cruise box and TB was too tight, so when I loosened it the idle dropped and it revved normally. I didn't bother checking the voltage on the TPS because the cable was pretty tight, which didn't seem right. How that changed? I don't know.
 

I think 9 or 10 on the TPS is correct. Thats what I always see. It sounds like the cable was your real problem.
Jeff O.
#1886/2000
 

I too have noticed differences in TPS %. I have the pocketlogger software and a Sony Clie SJ30. When I am watching actual values, my TPS reads 6% at idle and only 89% at WOT. I KNOW these figures are wrong because I have an AVC-R and I can see TPS and they are correct. 0-100%. I actually diagnosed a bad TPS a few years ago thanks to my AVC-R. I had a bad intermittent bucking under load and was able to see the TPS signal going to 0% for a moment. Anyone else had bad TPS values from their logger?
 

ken inn

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Feb 23, 2001
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krum texas
if i remember correctly, the afc is adaptive, maybe the avc-r is also? so whatever the tps max is, eventually it will be come 100% according to afc. i would bet the avc-r has the same function. but the logger is showing what ecu is seeing, and i would think it would be more accurate.
 

Thats why you really need to check it with a voltmeter. It should be .48 to .52 when closed, and I think it should be at least 4.5 volts wide open, but I can't find that spec right now. I know on the TMO logger you can see the sensor as either a percentage or as a voltage. .89 sounds a little low to me.
This FAQ shows how to check the resistance of the TPS:
http://www.plymouthlaser.com/tps.htm
Good luck,
Jeff O.
#1886/2000
 

spoulson

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Middletown, DE
After adjusting throttle linkage, it dropped to 7.8% according to MMcd (the russian thing, which is actually pretty nice)
 

The voltage between pin 3 (in my mind it goes from the top down) and a ground or the neg. battery should be jsut as posted above, .45~.50 and WOT is about 4.5+ volts. I just ran through these test while trying to get my AFC II installed as the pinout I had was wrong. That was a pita.
 

Nate

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Feb 23, 2001
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Worcester, Pa
TPS should sit at 10-11% at idle if it's adjusted correctly. This should work out to about .5 volts. Full throttle according to the voltmeter should be just under 5 volts, like 4.98.
 

spoulson

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Middletown, DE
Ok, so I guess I didn't fix it?

So how are you measuring voltage to a harness that's plugged in? The web site describes measuring resistance across pins, but not voltage.

So if the TPS/throttle cable was adjusted right before to sit at 10, then what could be my idling problem? I suppose it really could be that the TPS was adjusted incorrectly and the cable was too tight, so it read 10 but the throttle was very slightly open?
 

Nate

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Feb 23, 2001
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944
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Worcester, Pa
I use a probe to poke into the wires while the harness is plugged onto the TPS sensor. You could also use the closed throttle position switch to "adjust" the tps's "closed" position, but that's kind of half assing it. I've done it, but I usually end up adjusting it correctly at some point after that.
 

Arty

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Sep 9, 2002
Messages
384
Location
Victoria. Australia
You need some long sharp probes for your meter, you can either pierce through the insulation on the wire or run the probe along side the wire into the back of the connector until it contacts the wire terminal.
I could never find what I thought were suitable probes, so a few years ago I made some probes out of 10cm long sewing needles, empty ballpoint pens and some epoxy glue. They are invaluable.
 

ken inn

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Feb 23, 2001
Messages
7,529
Location
krum texas
using radio shack connectors, you can build yourself a nice test link. just get male/female ends, make a short length of wires to connect the cas and the harness, and on the + and - ends, run an extra wire and use that wire to probe. takes about 10 minutes, i then used mini alligator clips for the probes to the meter. when done, unplug the test harness, and plug in the connector. you probably got the stuff lying around. it's only 3 wires.
 

turboflanagan

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Mar 5, 2001
Messages
2,570
Location
Peachtree Corners, Georgia, USA
I use wig pins, sewing "t's", they have a bunch of different names. Got a whole bag full from my mom, but they can be found at fabric stores. Looks like a needle with the top bent into a T. Stick that into the backside of the connector and attatch test lead to the wig pin.
 

To test the voltage on the TPS, just stick the probe into the rubber boot around the #3 wire and check it against the neg. battery terminal.
 
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