Old car, new/used parts?

RebTech

I have a 2001 Toyota Corolla VVTI S Auto with 115k on the clock. It's in very good condition considering, except I've been warned brake pipes will need replacing for next MOT, and this fault.

It tends to hesitate before accelerating, and the engine management warning light is on most of the time. Also the mpg has dropped from around 37 to 33. The chap who services it for me, Toyota trained and entirely honest I believe, says it's the throttle position sensor and/or throttle body that needs replacing, and we're talking relatively big bucks, I think he said £400-500, for the parts, new.

I got the bits used off the net but it seems the throttle body is wrong, there's an "extra web" on it and using it the idle rpm won't go below 2k. The supplier said they'll try to find correct part and replace but I've been waiting about a week now so I doubt they have it in stock and don't know whether they'd try to source elsewhere or are just delaying for no good reason.

What do people think is my best way forward here? Could it be worth paying for the new part, on the basis I'll know it's right, and I can reasonably expect the car to last a few more years? (I drive maybe 10k a year.)

bod1467

Does this car have an engine management computer? (i.e. can a computer be connected to read off fault codes?) If yes, what are the fault codes, and do these point to the TPS as being the cause?

Different car, but on my old Ford Escort [1991] I had a similar issue - EW light coming on, sluggish acceleration, and sometimes would cut out altogether ... the crankshaft timing sensor was the cause. (Apologies if that is actually what the TPS is).

EdGasket

The throttle position sensor is just a variable resistor; like the volume control on a radio. It shouldn't be more than about £50.

As for the throttle body, I doubt this is the cause unless it is severely coked up in which case just clean the existing one. What is there to go wrong on the throttle body? Isn't it just a metal cylinder with a throttle flap??

colino

Normally I'd be encouraging you to keep the devil you know, but in this case I would get rid of it. Toyota had a formidable reputation for reliability and longevity, but that was a long time ago and as you have found, they joined in with the other manufacturers, making similar components but with frustratingly small differences to make them unsuitable for other models.
How good and age appropriate is your Toyotatech? With an auto I'm pretty sure there are additional vacuum pipes that run to the throttle body that need careful checking, but he may well be right and the throttle body is goosed and you will either waste your time fitting an old one that may well have the same fault, or discover old model parts from Toyota are made from unbeleivabum and cost more than the cars worth.

RebTech

bod1467 wrote: »

Does this car have an engine management computer? (i.e. can a computer be connected to read off fault codes?) If yes, what are the fault codes, and do these point to the TPS as being the cause?

Yes, don't know the actual codes but apparently they refer to the TPS. Don't know why the mechanic also suspects the throttle body.

Different car, but on my old Ford Escort [1991] I had a similar issue - EW light coming on, sluggish acceleration, and sometimes would cut out altogether ... the crankshaft timing sensor was the cause. (Apologies if that is actually what the TPS is).

I think this is a different thing. It isn't generally sluggish, but if I try to give it just a bit of gas to bring the speed back up to 30 from 28, say, power drops away at first then comes back up to what it should be if I push the pedal down just a bit more.