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Throttle postition sensor replaced[1800/73] posted by Daren Stone on
Wednesday, 2 June 1999, at 1:55 p.m.
"Transformed" is the word that comes to mind when describing how my ES runs with the new throttle position sensor. Several of you awhile back suggested this was the culprit when I described the intermittent stumbling and asked for advice, but for some reason or another it took me until now to actually replace it. Wow.
The specifics are a '73 ES (air & automatic) that I bought from the original owner, who upon handing me the keys told me about this "stumbling" problem the car exhibited every so often. After having it ahwile I replaced all the misecallaneous replaceables (filters, hoses, injectors, ignition components, etc. )and adjusted everything, but nothing made a difference. Then I undertook the performance top-end rebuild, as documented here awhile back. Still no difference, if anything it was worse (which kinda makes sense since the engine now has more power, and thus as a overall percentage loses more power when it stumbles).
I kinda got used to it, then over the Memorial Day weekend I drove ~ 300 hwy. miles and experienced new levels of annoyance. Once home I committed myself to resolving this problem, and hit the bullseye the first shot.
With the local dealers wanting $70 + and having to order it, I found myself once again thankful for Swedish Auto & Collision, who had it on the shleves at $43. Armed with a Phillips screwdriver, a DVM and feeler gauges, it was installed and adjusted in under an hour. (The thing that took the longest was trying to determine which of the four leads you connect to the DVM).
I managed to construct some late night errands requiring that I get on the highway, and Lord a-mercy what a difference ! In every phase of running the car is smoother, and I cannot wait to log enough miles to see if the mileage has improved. Before I felt tired driving the car over long distances as it seemed that an almost constant modulation of the accelerator was necessary to maintain speed. Now it just runs wherever you put it. My only regret is that I wish I had done this earlier ....
All for now ~
Daren
Re: Throttle postition sensor replaced[1800/73] posted by Mark Fleming on
Wednesday, 2 June 1999, at 2:53 p.m.
Did you every try cleaning the contracts? I replaced mine to fix the stumbling (after trying other stuff). While the old one was out I cleaned it with alcohol and a Q-Tip. It then tested okay, so I now have a spare. They must finally wear out, but they can be tinkered with to extend their life.
Mark Fleming
73 1800ES Car runs fine, I still stumble.
Re: Throttle postition sensor replaced[1800/73] posted by MikeH on
Wednesday, 2 June 1999, at 9:19 p.m.
I have had great success by cleaning the tiny strips with a clean lead pencil errasor and then electrical cleaner. When it begins to stumble I get out my errasor, clean and then I'm good for another two or three years.
Re: Throttle postition sensor replaced[1800/73] posted by Marty on
Friday, 4 June 1999, at 12:38 p.m.
Please excuse my ignorance but what and where is the throttle position sensor. I've tried looking it up in the Haynes, Chiltons, and Foreign Autotech manuals and have found no trace of it.
Thanks
--marty 73 1800es 61k
Re: Throttle postition sensor replaced[1800/73] posted by Don Foster on
Friday, 4 June 1999, at 1:19 p.m.
Marty --
The early D-jet injection system used an electrical switch to sense the throttle position. This switch is mounted on the intake manifold, right at the throttle shaft, and is a black plastic box about 2"x2"x1/2". It also has an electrical cable attached.
This switch, or sensor, has a zig-zag or sawtooth pattern on a printed circuit board, creating a pattern of electrical contacts. As you open the throttle a wiper rotates with the throttle shaft, crossing these contacts and generating electrical pulses. The FI ecu counts the pulses (crossings) and can determine throttle position.
When the throttle returns to idle, a different switch contact closes, telling the ecu that the throttle is back at idle -- and resetting the counter to zero.