TPS Weirdness

[sketchman]

OK, I'm convinced my Festiva is possessed now. The TPS seems to be physically working as it should. The little arms aren't grounded together when they shouldn't or anything. BUT, when I tested things with my multimeter, some strange things happen.

Haynes(and another thread on here from a while ago) tells me the pins go reference, signal, ground from to bottom. So following the directions to back probe test things, I get nothing that I should. Testing the reference voltage gives me nothing. Testing the signal voltage gives me 12.47 volts. AND testing ground with the battery neg post shows no continuity.

Out of curiosity, I mess around a bit more to find that there is continuity between the "signal" pin and ground. I pop off the black rubber boot to find that indeed, there is a black wire in the middle. Now I'm lost. What in the world is going on?

The sequence(as best as I can tell) is reference, ground, signal, but signal of course is mighty goofed up at 12.47 volts.

[blkfordsedan]

I tried he same thing with mine this spring and got wierd results, inconsistent with the Haynes manual. I assumed the TPS was bad, so I installed a spare. Got the same results, so I concluded that I either had two bad TPS sensors or I didn't know what I was doing. Since the car ran OK with either TPS, I deducted that I didn't know what I was doing and took the passive-aggressive route. I opened a beer, sat in a lawn chair and forgot about it. I'll be watching this post to see what answers you get.

[sketchman]

I actually rearranged the pins in the plug to the "proper" way and gave that a go before unhooking the thing and leaving it unhooked. Car runs fine without a tps at all.:???:

[sketchman]

Question. If the car runs fine without a TPS, why do I need one? I know the functioning of a TPS in my neon does contribute to the engine running, which you can easily see when you unplug it. If the car doesn't care about it, why is it there?

[DrMaxwellEdison]

interesting question... if there is a way to omit, can we get something in a thread or something like a sticky? just seems like it'd be an interesting bit to know... also is it a specific year or is it a year range like black ford sedan has a 93 (according to signature) could it work on my 90 (I've noticed mine jumps about 500 rpm every once in a while...

[blkfordsedan]

Question. If the car runs fine without a TPS, why do I need one? I know the functioning of a TPS in my neon does contribute to the engine running, which you can easily see when you unplug it. If the car doesn't care about it, why is it there?

I'm guessing it's main purpose (in our case) is to signal WOT to the ECU. Probably tells the ECU to go to open-loop mode, enrich the fuel or something like that. WOT performance would probably be hindered without it................Just a guess.

[sketchman]

Still wondering about this. Thought I'd bump it.

Anyone else with this messed up TPS wiring figure anything out? I'm still driving without one at all, and thinking about making my own "system" with microswitches, since it's really just a switch to tell when at WOT or closed throttle or neither.

[Festiva Time]

What the TPS does....

Question. If the car runs fine without a TPS, why do I need one? I know the functioning of a TPS in my neon does contribute to the engine running, which you can easily see when you unplug it. If the car doesn't care about it, why is it there?

From 1990 Ford Festiva car shop manual (page: 24-05-10): ...It detects idle and heavy load conditions based on the opening of the throttle valve. The sensor sends a signal to the ECA when the throttle is in the following positions:

IDL- Throttle vale opening 1.5 Degree or lower (idle or deceleration)
and
PSW- Throttle valve opening 70 Degree or more (heavy load condition).

[sketchman]

So, with nothing hooked up to it, would it stay in "no load" or "loaded" mode? I'm thinking "loaded" since my gas mileage is fairly horrible for a Festiva. Got 32mpg last tank.