I've been having some idling problems recently. No vacuum leaks, timing is good. I know the IAC is working because I replaced it less than a year ago and it is obvious when it opens to try to give the engine more air. Anyway, I tried to check my TPS voltage and the results were terrible. With the throttle closed, I got .045-.046V. Yes .045-.046, not .45-.46. Opening the throttle did not cause the readings to change at all. This also confuses me because I had good throttle response and the engine ran smoothly everywhere except for idle, so I would think that the voltage readings would jump up to where they were supposed to be when I opened the throttle. I am assuming I need to replace the TPS, but is it possible that I just didn't have good connections with my "jumper wires?" I tried using all kinds of wire, thick and thin, and nothing changed. What do you think?

 

on way to find out for sure how the tps reads is to disconnect it from the wiring harness. now take the volt meter you have and test for resistance

the resistance should move as you change the throttle possition if it doesn't your harness is prolly fubar

 

Okay...So how exactly do I test for resistance?

Wouldn't it mean that the TPS was bad if the resistance didn't change, not the harness?

 

according to Car Craft, chevy TPSs rarely ever go bad.

 

any idea why the voltage readings were so low and didnt change when i opened the throttle then?

 

my guess is that you were on the wrong setting with your multimeter. You were one decimal place off, right? There's a simple answer. I doubt you're really getting 0.047 volts. That's like what your body makes when you blink.

 

That's what I thought too, but then I checked the battery voltage while on the same setting to make sure I had it right and it was 12.7 or so. I tried switching the scale to two decimal places, but then all I got was .04. Maybe the multimeter is old and lost its accuracy to low voltages?

 

The reading should still climb. Verify you have appx 5 volts on the input.

 

k I'll do that tomorrow

 

Hell, do it now, it's only 9:30 pm for ya...

 

lol yes...and raining 44 degrees, im not going outside

 

And you guys always give us crap out here on the West Coast....

 

with verifying the resistance on the tps
take the main plug out of the tps
if you look where the main plug was you should see three little wires that the plug went into


one ground one input and one output. if you know anything about electronics it's just a basic potentiometer(sp?)

if you hook up the possitive of your multimeter to the input and the black to the ground on the tps while your on the resistance/ohms setting you should be able see what resistance you have on the tps
it usually should go fairly smooth up the range as you move the tps back and forth no dead sports or jumps
just move the tps back and forth slowly

 

This many replies and RX7 is the first one to go digging for problems......


I feel bad.

 

eh the tps on my mazda is fubar for a small portion of it. there is a nice dead spot on there
but hell I was driving the car for about 6 months before I even realized the tps wasn't even connected

really only caused a problem for off idle transition and around 1500rpms caused it to jerk a little

so yeah I have dealt with it before


and whats wrong with the import guy lending a hand
you thirdgenners are just here to bs while us real men (guys with the imports) do the work

 

lol...you just go round and round..dontcha?

 

OK I verified that I have 5 volts on the input.

I checked its resistance and it decreased smoothly as I opened the throttle and increased smoothly as I closed the throttle.

So what's next?

 

Now you need to make sure you have a ground on the TPS line, should come out of the TPS to the rear of the head, IIRC, the other wire goes to the ECM.

 

so basically just make sure all my grounds are good on the back of the heads?

 

Yes, that and you want to make sure the wiring is good...i/e verify continuity from connector to ground to make sure the connector/wire is good.

 

Wiring and grounds are all good. What do I do now?

 

You need to plug it all back in, and see if it now works. Lotsa electrical gemlins are cured via proper grounding and reseating conections.

 

Well I plugged it back in and burned myself a new chip with the idle speed set for like 1000 rpm just to see if it would stay idling up there. This seems to have fixed the problem, now I just need to make another chip with the idle set for 700 or so. I didn't even try checking the voltage in the TPS again. For some reason I still get the feeling I am checking it incorrectly because it has 5 volts input and the resistance changes nice and smoothly. Oh well.

 

maybe you are checking on the incorrect wires?


wonder if your checking on the input and the output wires rather then the output to the ground?