throttle position sensor 1990 Civic - junkyard part?

Hi,
I have a question about my 1990 Civic. It has had problems recently with bogging down, stumbling, and seeming to stall. It just set the trouble code for the throttle position sensor. I was going to replace
this, but found out the sensor isn't sold separately, only as part of the throttle body. A new part is $450 or so, a junkyard part is $40.
I have some questions about doing this, that mostly relate to the value of the car: - Is this something I can do myself, or should I have a mechanic do it? There's lots of hoses and so forth on the throttle body and it seems like it's easy to get wrong. - What's the reliability of a junkyard part? - The bigger question is the car is approaching 17 years old and has 263K on it. Is this really worth fixing?
Thanks in advance, Derek
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dex3703 wrote:

================================== Draw sketches before you tear it off, get a gasket from the dealer, try to get a TB off a lower-mileage car. _Well worth it_ .
Did you inspect the connectors VERY carefully? The computer gets the signal via three wires and two or three connectors.
'Curly'
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dex3703 wrote:

yes it's worth fixing. registering /any/ replacement vehicle is going to cost you more than $40. you can buy just the sensor from a junkyard or the whole throttle body. google these honda groups on how to replace just the sensor. you can even do it with the throttle in place if you're careful - minimal plumbing that way and no gaskets. if you remove the sensor yourself from a junker, it'll be practice for how to replace it on your own vehicle. get a sensor from an automatic - significantly less wear. write back if you get stuck.
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A code 7, right?

Check the TPS with an ANALOG multimeter (the kind with a needle) before condemning it.
Use a straightened paper clip to backprobe the TPS connector wires. Leave the TPS plugged in. Turn the ignition to "II" (all dash lights will come on). Set the multimeter to 25V DC. Connect the multimeter to one of the wires and a ground. Open and close the throttle by hand.
You will find that one wire will give a steady 5V all the time. One will give no reading. The third wire's voltage will increase and decrease as the throttle is opened and closed.
If there are no hitches in the multimeter's needle travel all the way from open to closed, and the voltage rises from roughly 0.1V to 0.45V, then the TPS is OK and your problem lies elsewhere.
At your car's age, the problem may well be a broken (or intermittent) wire connection somewhere.
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Tegger

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Corrections:
From about 0.1V to about 4.5V.
Set the multimeter to 5V DC for the variable wire. Any higher and you won't be able to see the needle's movement.
(I really should proofread better before I post...)
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Tegger

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Hi all,
Thanks for the responses. Yes, it is a code 7. I read elsewhere on the group that this code is generally reliable.
The problem has been over the last couple months, with the code set last week. I presume this would explain the bogging, dropping revs and seeming to konk out. It especially happens (when it does) when I'm at whatever speed I want, and then let off the gas. The problem is intermittent but does seem to be getting generally worse.
I guess I'll tackle this next weekend then. Should I expect weird failures like this going forward?
THanks, Derek
Tegger wrote:

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dex3703 wrote:

the sensor has a carbon track that wears in the place where you most commonly put the throttle while driving. if you disassemble the sensor, you can see it. easiest solution is to replace the whole sensor. you can "repair" the sensor by splaying the brush so it contacts a wider track inside, but it's a lot of effort.
bottom line, replace and enjoy. symptoms are exactly as you describe. once replaced, you'll be back to normal like nothing ever happened.

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Best solution,maybe not the "easiest"...

I suggest trying a electronic contact cleaner/lube spray.(lightly) The TPS is nothing more than a potentiometer.

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Jim Yanik wrote:

having done it both ways, i say doing it on the vehicle without removing the throttle body [dpfi] /is/ the easiest way. use a chisel to start the shear bolts rotating, and robert's your mother's brother.

doesn't work - it's utterly sealed.

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I meant replacing the sensor being easier instead of repairing it. (then replacing it anyways...IF you can find a new TPS to install w/o buying the whole throttle body.)
Not removing the whole TB being easier.

You said "splaying the brush so it contacts a wider track inside," indicating YOU got it open for access,so the element CAN be sprayed. It just has to be opened up first. It might get you by until you can get a new TPS from somewhere shipped in. I doubt spraying it would be a lasting repair.
(of course,you could always drill a tiny access hole for the spray tube,and seal it with a piece of electrical tape to keep dirt out,if you learn where it's safe to drill.)

Curious;did you find a place to buy a NEW TPS(other then a dealer),or did you salvage one from a junkyard part? (sensor only,not a whole throttle body)
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Jim Yanik wrote:

right, replacement is the way to go. if you use a junker, seek out the automatics as donors.

first time, i painstakingly dremeled it open - it took ages. this was before i realized you could remove a sensor from a junker in about 5 minutes. once you have it open, you can completely disassemble and clean - no spray required.

if you can buy new, i'd love to know where from!

good luck! i still don't think it'll work because on mine, the carbon track appeared worn through - spray won't fix that.

junk yard - sensor only. it's literally 5 minutes - all you need is a small hammer and a small [sharp] chisel. use the chisel to nudge the shear nuts around so they turn by hand. on the dpfi it really is a piece of cake. on the 4pfi, it's much harder as it's all behind the manifold.
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