'88 accord throttle position sensor insanity!!!

My Accord Lxi '88 has a problem. It began as a combo initial big engine
start-up rev-v-v-v, then drop down to a regular idle/ rev cycle.
Although annoying, in gear the car operated fine, but at stops reverted
to the idle/rev cycle. Was getting less ruly and prone to rev-v-v-v.
I got an electronic diagnostic that fingered the throttle position
sensor for replacement. My car parts source said the replacement part
was 'obsolete.'
On inspection, this part appeared riveted on to the throttle, which
bolts onto the throttle body. Went to a junkyard, retrieved a
replacement throttle, when installed it reverted to the better behaved
original routine. Returned it for not fixing things.
When I reinstalled my original unit, now it was rev-v-v- all the time.

Went backed to junkyard with new knowlege that with a dremel tool
grinder making a slot, the actual throttle position sensor can be
removed and retrieved a substitute in this manner, but the car wasn't a
wreck.
It reved as before.
Is there any reason that a replacement throttle position switch is not
available by honda without replacing the entire throttle body for over
$600?
Am I screwed?
Please, help me. I am at wits and financial ends.
Paul

 

I wonder if your trottle control cable isn't binding or something -
that may also throw off the throttle position sensor.
What happens when you look under the hood? Does the trottle return all
the way to normal?

Also carefully check for a vacuum leak. Thing like that could cause
weird things like that to happen too.
Here's a trick I've used to find vacuum problems: spritz a shot of
ether (starting fluid) near the suspected spot. The ether will drive
the air out and cause the car to run normal or at least change, albeit
for one hot second. It will let you find cracked hoses, etc.
Just be careful where you "spritz", as ether is obviously flameable and
you probably like to have eyebrows..

Remco

 

I'd look at coolant level, base idle speed, and controlled or uncontrolled
vacuum leaks. I'd look really carefully at the Fast Idle Valve (a
controlled vacuum leak) after you've looked at the others. They go bad
quite often on older fuel injected accords.

If you still are certain it's the throttle angle sensor, you should be able
to get a complete throttle body for less than 50 bucks, considering you can
get an entire engine for an 86-89 accord for $100.

www.car-part.com will have some nice prices.

 

first, the position sensor is repairable. i wrote up how to do it a few
weeks ago. google is your friend.

second, what makes you sure it's the tps? what code do you get? if you
tried two replacement units & it didn't finger the problem, it's not the
right repair! i've limited direct experience with the symptoms you
describe, but it sounds like it might be an air lock in the coolant.
try bleeding the system & report back.

 

There should be a bit of slack in the throttle cable when fully closed.

Another approach is a propane torch. Don't light it, but aim the nozzle
close to the area of the suspected leak, then turn the gas on momentarily.
If there's a leak, the idle will change noticeably. If there's no change,
there's no leak.

 

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A shot TPS doesn't cause those symptoms. To diagonse a bad tPS, use an
analog meter and put it across the center and one of the outer pins of
the TPS and slowly rotate the throttle. You'll see itjump or dip when it
hits the exact position you go at highway speed.

'Curly'

 

That's a cool trick - Thanks, John!
(always redoing my 1925 house, I usually have a propane torch floating
around - not always container of starting fluid)

 

What do the symptoms sound like to you?
Paul