Engine Stuck At Idle

[pako2010]

I'm writing from France about a problem with our 1999 IS 200, manual transmission, 110k km (about 70k miles). The other morning the engine got stuck at idle -- depressing the accelerator didn't change the engine speed at all, and the check engine light came on. The car had been parked indoors and the problem came up within a few blocks of leaving the garage, with the engine just warming up. We parked the car and came back the next morning and the engine seemed to respond normally, but we didn't really drive it. We had the car towed to the local Lexus dealership, which wants to replace the clutch. This doesn't make a great deal of sense to me. Any ideas?

[fjcfarrar]

If it is as you describe including the engine warning light; a faulty clutch is as unlikely a cause as a Unicorn under the bonnet - although I suppose the clutch could be worn out as well as your engine fault.

If the car had been warmly garaged indoors and went out into very cold conditions, massive condensation in the engine-bay may have caused this or maybe dirty/poor connections to the throttle-body or poor-connection/faulty lambda sensor etc. Unlikely to be anything very expensive. If you don't fancy checking these yourself, take the car to a different Lexus Dealer.

[steve2006]

Are these cars "Drive by Wire" or conventional cable controlled throttles?

A common cause of the problem in other vehicles is the throttle pedal position sensor which basically tells the engine ECU where the pedal is and increases/decreases the revs accordingly this is assuming it is DBW.

Also if the check engine light came on there will be a diagnostic code stored which when read would point the dealer in the right direction.

I cannot see where the clutch replacement comes into the equation and I would get a 2nd opinion 1st.

[pako2010]

Thanks to both of you. I'm embarrassed to say that I don't know if the car is drive-by-wire, and it's still at the dealer so I can't take a look for that (or the unicorn!) The temperature difference between the garage and outside was not dramatic so we probably exclude the condensation hypothesis. Since the orignal posting I've learned that the "stuck in idle" is probably just the car switching to "limp home mode", which might have been triggered by a sensor problem, or maybe something else. In any event, we'll have a well-informed chat tomorrow with the Lexus service manager, who was away last week when one of his wizards proposed replacing the clutch. Thanks again.