I have an 89 thunderbird 3.8l that had a sparadic idle and a check
engine light that comes on at a drive idle occasionally. The code
indicated a bad TPS. I got a new one and after removal of the old
noticed the contact points of the old one was advanced about 45
degrees from the new one, I attempted the install anyway. After
restarting, the check engine was on constantly and was at a very low
rough idle. I shut it off after a minute, removed the assembly and
advanced (wound) the TPS to match the old sensor position and
reassembled. The engine started perfectly. But, after a quick test
drive the park idle increased to 16K. My question is this...
Does the computer take a little time to adjust to a new sensor and
position and in turn was I too quick to advance the sensor... should I
have test driven it the first way even though it was running like crap
with the check engine light on and the engine would have self
thanks in advance for any help... Joe
====================Generaly the TPS will come out of the box ready to install with the throttle
at idle. The engine does need time to adjust, a quick drive in city and
highway will be fine. The light should be off if all is well. Install the
TPS the way it came out of the box if posible and diconnect the battery for
a few minutes. If the light returns after you start it up, scan for the
codes and start over. If the light is out, take it for a drive and see what
happens. If you drive it and the light doesnt come on and it still idles
wrong clean the throttle bore and IAC. And then drive it again.....GL
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com ).
Thanks for your advice... I tried as you requested. Put in the
default way, the light remained on even after disconnecting the
battery and it is on all the time and has a very low idle even after
a 15 minute drive.
Advancing the new sensor too match the old one makes the light
disappear immediately and idles perfectly at first but obviously too
high of an idle once driven a short way.
Does it make sense that the new sensor would have its contacts
retarded 1/8 of a turn? Or should I go and try another one?
Thanks again, Joe
Please let me butt in with a question. Have you read the codes after this
job? There *might* be something else contributing to the problem. When I
put the new TPS on my '84 with throttle body injection, it required a small
turn to install. I assumed the small adjustment was to be certain of
reading the fully closed throttle position. I suspect your IAC (idle air
control thingie at throttle body) might be sticking...
=======================1/8 of a turn is nothing, It a slot right? Sounds like you got it
right. ----OK, you have no light now correct? If so all is good with the
sensor. Now, I would suggest you turn your attention to the Idle Air Control
motor. It is a VERY common problem on Fords. If you have not been messing
with the idle stop screw and you have a few bucks, just get a new one. It is
also a good idea to check the throttle bore, if black and gooey, clean it
with carb cleaner. You can also try to clean the IAC (idle motor), you might
get lucky. GL
I went back and got another TPS. Indeed the part I got was incorrect,
right box, incorrect part (Autozone). Popped in the new part and it
runs great, considering she has 180,000 miles on her. Thanks for
everyones advice! Joe
Great car, why Ford killed this model, I will never figure out!
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.