with the top screw unscrewed slightly, the car runs awesome.

 

screwed in... it runs like crap.

 

ahhh this car's making me grey

 

I have found the best way to check the variable resistor on a TPS is with an analog meter ( one with a needle indicator) rather than a digital readout meter. With an analog meter the indicator needle will make a smooth sweeping motion throughout the resistance range. If there is a dead spot the needle will jump.

 

I had a TPS that would give a bad reading if there was any side pressure on the throttle shaft. This may be your problem if the mounting screw pressure is changing the resistace output.............Roger

with the top screw unscrewed slightly, the car runs awesome.

 

screwed in... it runs like crap.

 

ahhh this car's making me grey

 

Well it seems we've pinned it down to the idle switch portion of the TPS. You need to adjust it so that it closes those contact (A and when the throttle is in the closed position.

 

Loosen both screws, and rotate the whole body of the TPS slightly clockwise, or upwards. this will make the contacts of the TPS close(if they are working, which it seems they are) There is a description of this in the FSM. That part wil be the same for any year SPFI motor. that is why the mount holes on the TPS are slotted, so it can be adjusted to set a baseline.

 

The consistant readings between the 2 TPS is encouraging. You could have a meter reading off slightly like DAERON suggests.

 

BTW you're 86 is the first year of SPFI, so you're original TPS is the oldest possible TPS you could have.

Well it seems we've pinned it down to the idle switch portion of the TPS. You need to adjust it so that it closes those contact (A and when the throttle is in the closed position.

 

Loosen both screws, and rotate the whole body of the TPS slightly clockwise, or upwards. this will make the contacts of the TPS close(if they are working, which it seems they are) There is a description of this in the FSM. That part wil be the same for any year SPFI motor. that is why the mount holes on the TPS are slotted, so it can be adjusted to set a baseline.

 

The consistant readings between the 2 TPS is encouraging. You could have a meter reading off slightly like DAERON suggests.

 

BTW you're 86 is the first year of SPFI, so you're original TPS is the oldest possible TPS you could have.

 

To calibrate the TPS properly, you need to get a set of feeler gauges.. I bought mine at a local auto parts store with a decent selection of tools.. about 10 bucks... you need to set one size in between the throttle drum (the bit that the cable attaches to) and the throttle stop screw to indicate a 1* opening of the throttle, and then use another to force something like a 2.5* opening of the throttle. The page gloyale mentions outlines it in detail; if you have difficulty finding it i can email you a one page pdf that goes over it all.

I'm going to get a set of feeler gauges tomorrow and give it a shot.

 

Terminal B is the ground wire terminal. Continuity to ground with the TPS mounted is incidental.

 

Well you should just get 1 or infinite. Until the throttle is opened slightly, then full contact Zero ohms

Green wire at check connector should have Zero resistance with Terminal A not B wire of haness. But harness measurments should be done with the ECU and TPS connectors unplugged, otherwise you could be measureing resistance of the ciruits inside ECU.

you should not be getting Negative Resistance values. 1 means infinite resitance, or a total open circuit, no conductivity. -1 means the meter is tring to read a resistance that is off the scale. You should set your Ohm meter to a higher scale like 10 or 20k ohms. The values you are trying to read are between 1k ohm and 10k ohms.

 

 

Are you testing it with the connector unplugged? Here's what it shuold be. Testing TPS itself, not plugged in.

 

Restistance between A(idle) and (ground) should be Infinite at throttle open, 0 or near zero (.1 ohm or less) at throttle closed.

 

Resistance between B(ground) and D(+V) changes with throttle opening between 3.5 to 6.5K Ohms

 

Resistance between B and C(signal V) changes with throttle opening. Less than 1K Ohm at closed, Greater than 2.4K ohms with valve fully opened(80% of resistance between B and D) Restistance should increase and decrease continuosly and smoothly between B and C.

 

"Resistance between B(ground) and D(+V) changes with throttle opening between 3.5 to 6.5K Ohms"

 

Is this correct? This part of the test procedure that says there should be variable resistance between B and D?

 

I am having a off-idle hesitation and getting a TPS code. I have 4 TPS and all of them show about 4.5 ohms resistance between B and D and that value is unchanged with opening and closing of the throttle. The unlikely odds that I have 4, similarly failed TPS makes me want to confirm. Aside from that, all 4 of my TPS test Ok In all other parts of the procedure.

 

1992 SPFI Loyale. 170k miles.

Edited January 25, 201313 yr by markjw