Got a problem with a toyota avensis (not mine) - It's a GS, estate, and has a 1.8 multipoint engine in it. It's running fine when cold, but for some odd reason when the engine warms up, the redline actually seems to drop, and the revs will not rise above a certain amount, and it gets worse the hotter it is.

Any ideas?

*sticks neck out*

Coolant temp. sensor.

*sticks neck out*

Coolant temp. sensor.

Any advice welcome - no neck sticking out required.

Will advise that's the first thing to check.

Its the logical thing to check, surely? The only way the car will reduce the revs itself is via the ECU, the only way the ECU knows the temperature of the coolant is via a sensor.

Well, the coolant temp sensor has been checked previously, unknowing to me.

Anything else to think of? :confused:

HT leads or plugs fried? I've driven a car with fried plugs (Ford Cortina with iron core plugs, it was that long ago), and when hot it ran badly, worse above certain revs, and those revs getting lower as the plugs got worse.

in my experience, the toyota engine is pretty sensitive to the plugs it runs.

if the alt is denso, then the plugs should be too.

deffo sounds like plugs gettin poor as they get hot

Toyota ECUs limit rpm depending on engine temperature, theoretically from cold you shouldn't be able to get anywhere near the limiter but as the engine warms so do max. permissable rpm. If it's not a sensor somewhere then it's almost definetly an ECU fault. First thing I'd try is a reboot if the sensors are fine - disconnect the battery overnight and see if it returns to defaults.