baughb'smx6

I'm checking the tps on my 86 gxl, but the only write up I ould find was for a t2. I'm not sure if they are the same, but if so then I'm confused. At idle, it was 1k ohms, and went up a bit, but after that it nosedive to 500 ohms from about 1/8th throttle all the way to wot. Am I doing it wrong, or what? Oh, and I backprobed green and black wires.

HAILERS

Non Turbo and turbo..........same check out.

It's done with a fully warmed up engine. Engine turned off as you do it. You unplug the TPS conector plug from the harness. Then follow the instructions by putting the meter on ohms and touching the two terminals on the TPS pigtail connector. Make sense? Remember, connector disconnected and key to OFF if doing this.

Now that bull is over....................do it much differently than that (called the sensible method or accurate method). Fully heat the engine up. Keep the engine running if possible (that's just to keep the water temp up, not required if you don't dilly dally around).

Now look at the connector attached to the TPS itself. Leave the connector connected to the EM harness. Now look for the green wire with a red stripe (G/R) in the half of the plug on the EM harness side of the conenction. Somehow backprobe that wire where it goes into the connector OR ***** it with a sewing needle while your positive meter lead is touching it. Negative meter lead on a known gnd point (like the case of the alternator). Meter on VOLTS DC. Meter should read one volt DC. It should read one volt dc with the engine idling or even with the engine OFF and Key ON (fully hot engine required). If it does not read one volt, turn the adjustment screw til it does read one volt. If it reads say 0.95vdc.......that's fine. If it reads 1.05 volts,......that's fine. It should read APPROX 1vdc.

baughb'smx6

Ok, so I did it the first way, and at closed throttle it was apx. 1k ohms. However, for the first split second I moved the throttle, it went OL, but then went back to apx. 1k ohms and steadily increased to about 4.5k ohms. However, it reached that point with about 1/4 of the throttle sweep remaining, and it stayed at 4.5k ohms for the rest of the sweep. The second way that you said it read apx 1 v, I don't remember the actual number.

So does this equal a bad TPS?

HAILERS

Stare at the pluinger on the TPS while you open the throttle. The plunger is not being touched by the linkage after the throttle is moved just....say twenty degrees of full travel. The TPS is fully open/extended at that point.That explains why the reading is a steady 4.5 ohms thru the rest of the travel of the throttle linkage.

The narrow range TPS Plunger, on a series four or series five is only engaged until the point the linkage travel is enough to START opening the secondary throttle plates. It only measues the travel of the linkage from full PRIMARY throttle plates being close TO just when the secondary throttle plates START to open. IT ignores the rest of the throttle movement from there to full open. It has no requirement for measuring the rest of the travel of the linkage.

IF you look at the CONTROL UNIT pages of the FSM and look for pin 2G (TPS INPUT) you'll find the requirement for the voltage is *Approx 1vdc* at idle. So knowing that, all one has to do is tap into the output wire of the TPS conenctor (green/red) with a meter and with a fully warmed up engine, check to see if the reading is Approx 1vdc or not. IF not, then turn the screw til it is Approx 1vdc.. What is approx??? .95vdc or 1.05 in my minds eye meets APPROX definition.

The FSM has a procedure for checking out the TPS's GUTS. It has a engine fully warmed up and has you disconnect the TPS connector and then check the resistance of the TPS from full closed (meaning hand/foot off the accelerator) and move the throttle linkage by hand looking for *opens* in the pots travel and looking for a given resistance at full closed and full open.

That procedure is not for setting the TPS, although 1K ohms is close enough at idle. I'd just rather have the plug connected and look at the output and the value given in the CONTROL UNIT pages of the FSM. Its much easier for me to do than Wasting my time doing something not meant for SETTING the TPS .

If your going to look for *opens* in the range of the TPS, I'd suggest buying a old fashion swing meter and watch it's needle while moving the linkage.

IF you don't have one, then backprobe the green/red with plugs conencted and hot engine, and watch the meter on dc volts while moving the linkage thru its full travel.

If a person has a SAFC or RTEK 2.1 he can set the TPS looking at the screen of the given display and if the figure is off........just move the TPS screw til the screen reads the right value. Done

Setting the TPS using the two LED light method (or Mazda test light rig) results in.....................an output voltge of approx 1vdc from the TPS to the ECU. The TPS output is used by the ECU for various things, one of which is the tripping of the relief and swtiching solenoids to control the ACV and also to recognize certain Zones of operation of the engine (see training manual).