UncleRay

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Had this code come on about a couple of weeks ago. First off, had the starter changed not too long ago, just to throw that out there.

In the mornings, the engine turns, but fails to fire correctly. Turn it again with my foot on the pedal lightly, and let it sit back at 500-1100 RPM. My VSC and VSC OFF lights are on, so this is critical I would have to say.

Went to my uncles shop, saw his mechanic, and when we did some tests, things were horrible. No misfires on spark plugs, every wire was good, the harness was changed ( same troubles ), the gas pedal being pressed didn't even register being pressed!

I do ECU resets, and it comes back on after every 50-100 miles. When it does, the car will stall.... on a freeway, on a local road, anywhere. The dash board does not light up, but the car needs to be turned on again. Press the gas pedal, nothing. Floor it, and car starts to move with a big jerk.

Should I change sensors? butterfly? accelerator cable? or the entire damn thing? ( Heard it's NOT cheap! Of course, the starter wasn't neither LOL )

mitsuguy

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assuming we are talking about the car in your profile, 99 GS400...

I would venture a guess that I can diagnose this over the internet without ever seeing your car... which is sad for your uncles "mechanic"

throttle position sensor... plain and simple...

if you look at the specifics of the code and how the ECU looks at the TPS and determines when to set this code, you will see that it is looking at the accelerator pedal position sensor and comparing it to the value from this TPS...

I would bet that if you were to hook up a scantool with the ability to see TPS percentages or voltage, you would see an intermittent drop out at a certain percentage, or that it is just wrong completely...

I highly recommend you have someone check this first, however, I'd put $20 that its the TPS... Even if you replace it, you will need a scantool to ensure it is calibrated properly - there should be a small amount of adjustment /play in the mounting bolts, and you will want to make sure that key on engine off, foot off the pedal, the voltage reported is 15% +/-1...


just to cover the bases, couple other things you want to ensure - that it is plugged in completely with no corrosion, and there is no moisture or broken / loose connector pins

one other quick note - if it's not the TPS sensor or the wiring for it, the only other real option for something being bad is the ECU... cross your fingers and hope its the TPS...

UncleRay

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Where can I find a diagram of the sensor's location? How easy is it to change it? DIY level?

mitsuguy

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its easy enough to find, but the problem is you will need a relatively advanced scantool in order to calibrate it... there might be a voltage reading somewhere, but the only way I know off top of my head is to look at the scantool percentages...

I don't have the manuals in front of me right now, but I would venture a guess that it is directly on the throttle body like most other Lexus... it'll be a sensor usually on the backside of the throttle body, maybe the front, either way, it will be opposite the side that has the cables for the throttle plate itself... usually has a 3 pin wiring harness going into it...

so, yes, easy to change, but, no, not easy to get working properly... sometimes you can get lucky... you could always just try a few different positions, but I don't think thats the way I would do it...

UncleRay

iTrader: (2)

Much thanks Mitsuguy. Will let you know how it goes :]



Would that be it?

UncleRay

iTrader: (2)

bumpity bump?

mitsuguy

iTrader: (2)

the one that says throttle position sensor, yes...

UncleRay

iTrader: (2)

Ordered from parts.com, and found someone who can actually do this for me! wootness