1987 Tbird Idle problem

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1987 Tbird Idle problem

July 06, 2005, 11:30:14 PM

I have an 87 tbird with HO conversion. It has new wires, plugs, rotor and cap. I have an idle issue. When i crank it it idles really low and when i put it in gear it will die. When i get to where i am going and put it in park...it will idle really high. I know fords are cold natured, but is there any ideas o how to fix the problem becuase i am tired of having rev my car in front of my work just to keep it cranked...Thanks

Re: 1987 Tbird Idle problem

Reply #1 – July 07, 2005, 12:34:57 AM

TPS,or Idle air controller (on the side of the throttlebody),vaccuum leak.I just finished my H.O. swap in my '88 T-Bird.Best thing I could've ever done.My idle was a little off,so,I set the timing and adjusted the TPS a little,and man what a difference.

Re: 1987 Tbird Idle problem

Reply #2 – July 07, 2005, 12:54:03 PM

check voltage ranges on TPS sometimes they get a little high so computer can't find the right place for the throttle plates. new switch is cheap enough also check the connetor and for pinched wires. this may give a low voltage signal. Also try this. Diconnect the battery (clears the codes in computer) remove air intake hose throughly clean air horn and both sides of throttle plate with a brush and carb cleaner. Pay attention to the small holes on the leading edge make sure they are not clogged. After reconnecting the battery it make take few days for the adapative strategy in the computer to balance everything but it should take care of any surging idle problem if the TPS is ok

Re: 1987 Tbird Idle problem

Reply #3 – July 07, 2005, 11:28:17 PM

stupid question: how do you adjust a TPS?

Re: 1987 Tbird Idle problem

Reply #4 – July 08, 2005, 12:39:04 PM

some of the TPS switchs have a very minor adjustment. the 2 screws at the top are seated in elongated holes. loosen these screws and slowy rotate switch while reading voltage with standard volt meter. the shop manual has the recommeded voltage for the throttle fully closed and fully opened. i beleive on my car it was .9 volt closed and 1.5 volts open. as you can see with such small varitions good solid and clean conectins are a must
hope this helps
walt

Re: 1987 Tbird Idle problem

Reply #5 – July 08, 2005, 10:56:39 PM

stupid question#2: Where do I put the voltmeter... Man, I miss carburetors...

Re: 1987 Tbird Idle problem

Reply #6 – July 09, 2005, 09:08:41 AM

Stick a sewing needle through the green wire coming off the sensor. Attach the red (positive) wire from the voltmeter to the needle on the green wire. You can connect the black (ground) wire from the voltmeter to one of the srews that holds the tps sensor to the throttle body.

I think I read that you can also put a needle through the black wire off the tps and connect your voltmeter's ground to that instead of using one of the tps screws. I didn't try it this way but the way I described above worked fine for me.

Re: 1987 Tbird Idle problem

Reply #7 – July 09, 2005, 04:58:40 PM

i have done the test an d gotten 1.78 closed and 4.85 open...how do i reduce these numbers??? Thanks everybody..

Re: 1987 Tbird Idle problem

Reply #8 – July 09, 2005, 05:21:59 PM

You do this just as baylensman said.
Unscrew the two screws that hold the tps to the throttle body just enough that you can wiggle the tps. Keep your voltmeter connected so you can set the tps at the proper position. Now you may be thinking there will be some major movement needed. As crazy as it sounds, the tps only need to move a fraction to change it's voltage reading. The limitations of how far the sensor wiggles between the two screws is what determines the voltage. Slowly move the sensor until you get a reading of approximately .98 volts. If you move the sensor to the limitations of the screws and can't get a reading of .98, you may have to elongate the holes that the screws go through. It's a bit of a pain to juggle, holding the tps at .98 while trying to tighten the screws and helps if someone can be there to hold the tps steady or tighten the screws. This is because if you let go of the tps and start tightening the screws, the tps will move and you will get the wrong voltage. I hope this helps.