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

 

===================================

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'

 

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.

 

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.

 

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...)

 

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

 

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.

 

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

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

 

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.

 

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)

 

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.