Off throttle problem*

[dudutzu]

I searched but I couldn't find anything related to my situation

So I drive a 99 SE V6 MT with a little over 120k miles
everytime when I go off throttle, in any gear(in higher gears doesn't feel as bad but is there), for a split of second the car accelerates like someone is pushing the gas and then cuts off, and that doesn't matter how slowly/smooth I back off, and is very annoying, the first time when noticed it actually scared me
I don't know when it started to do this cuz I got the car only few months ago, and was doing it since
and there is no CEL on or anything
the car appears to idle at a normal speed around 700rpms
what can it be and what to do to fix it?

thanks in advance guys

[solara90]

i might be wrong but i think it has something to do with the throttle position sensor delay? correct me if i am wrong?

[MisterTedster]

Did you recently do any engine mods? i.e. sri, bored tb, etc?

[dudutzu]

Did you recently do any engine mods? i.e. sri, bored tb, etc?

no
only thing I've done is this: forgot how you call it


but was doing it before that also

[99BlackSandv6]

Sounds like fuel delivery problem, most likely caused by the TPS (throttle position sensor) have a shop check it out for you.

[dudutzu]

anyone else has other ideas?

[jetbtkng]

TPS (throttle position sensor, i bet thats your problem, its just a plastic piece of >>I'm a douche<<, i replaced one already, although i did get a cell with it, but only when it totally failed, i bet its worn out..............

[dudutzu]

TPS (throttle position sensor, i bet thats your problem, its just a plastic piece of >>I'm a douche<<, i replaced one already, although i did get a cell with it, but only when it totally failed, i bet its worn out..............

to say that the TPS is faulty, but if the CEL isn't ON(at least for now) does that mean that if I check it with a multimeter gonna get that the TPS is in limits? cuz if it wasn't(within limits) the CEL would be ON, right?

[jetbtkng]

all it is, remember slot cars, well its just like the controller that makes the slot car go faster or slower, wires in a line wrapped on an insulator, and a metal arm going up & down rubbing against them, after time it gets worn & starts sticking...............

[solara90]

^ yeah they will usually get a dead spot in them from the usual 1/2 throttle or less which you usually use during normal driving.

You can easily test a TPS with an oscilloscope

i.e. look at the diagram here

http://www.aa1car.com/library/tps_waveform.gif

[Chinky420]

about how much does a new tps cost anyway?

[solara90]

you 1mz guys are lucky your can be replaced seperately and there about $60

http://www.autopartswarehouse.com/searc ... or&submit=


the 2az guys have to buy a whole new throttle body which is about $800 because toyota had some great idea to incorporate everything into the throttle body!

[dudutzu]

^ yeah they will usually get a dead spot in them from the usual 1/2 throttle or less which you usually use during normal driving.

You can easily test a TPS with an oscilloscope

i.e. look at the diagram here

http://www.aa1car.com/library/tps_waveform.gif

thanx
that would make sense
what if I don't have access to a oscilloscope, is any other way to test it to get the same result?

[dudutzu]

about how much does a new tps cost anyway?

I want to find the problem first and then start replacing parts, not the other way

[solara90]

Yes, i could explain it in my own words but ill just use the copy and paste method!

1) Test the TPS for signal voltage to the computer. Insert a pin through the ground wire and another pin through the signal voltage wire and connect the voltmeter probes to the pins using alligator clips. Start the engine. As you manually open and close the throttle plate, watch the voltage readings at the meter. The voltage should gradually increase from 1 to 5 volts and back to 1 volt. If you see an erratic or no movement of voltage signal, replace the TPS sensor.


2) Test the TPS sensor’s resistance. This is an alternate method to test TPS sensors equipped with a variable resistor. Unplug the TPS electrical connection. Set your multimeter to ohms. Connect the ohmmeter probes to the sensor’s supply and signal wire contacts. Manually open and close the throttle plate and watch the resistance reading at the meter. The resistance should gradually increase and decrease as you open and close the throttle plate. If there is an erratic resistance change, no change, or no resistance at all, replace the TPS.