Fast Idle

[V41LEY]

Car fast idling between 1500-2000 revs and is getting overheated as a result. Any ideas ?

[Johnniem]

Being a complete mechanical numptie and a new owner of a 450 Chimaera I am not usually warranted to answer techie questions. However, I have read on several threads of the importance of keeping the 'stepper motor' clean. This is apparently the thing that keeps the tick over regular (a sort of tick over '5-a-day') at 900 rpm. It is so simple to clean that even I was able to do it last weekend. See "the Bible" and it will all come to pass!

Check out the various threads on the TVR sections or go to TVR Chimaera pages or the TVRCC website. There you will find all manner of good information to take care of every waking hour in the weekend!

[TVR Thomo]

Defenately worth looking at the stepper motor first. It may have come loose or like johnniem said it may just need cleaned. There is also a base idle screw in the plenum which I think is anti clockwise to close and clockwise to open. This sets the base idle and the stepper will do the rest. From memory if you fully close the base idle and then open it at 2 and half / 3 full turns, with a good working stepper should idle perfectly.

[nikman]

TVR Thomo said:

Defenately worth looking at the stepper motor first. It may have come loose or like johnniem said it may just need cleaned. There is also a base idle screw in the plenum which I think is anti clockwise to close and clockwise to open. This sets the base idle and the stepper will do the rest. From memory if you fully close the base idle and then open it at 2 and half / 3 full turns, with a good working stepper should idle perfectly.

The plenum by the way V4ILEY, is the large fluted casing at the top and towards the back of the engine with the "450" label stuck on top.

[Cider Andy]

What are the symptoms of the overheating you describe? If the stepper motor is the reason the car is idling too fast it shoudn't cause an overheating problem.

[V41LEY]

Cider Andy said:

What are the symptoms of the overheating you describe? If the stepper motor is the reason the car is idling too fast it shoudn't cause an overheating problem.

Temperature is 100 plus and wisps of steam visible from the bonnet when in traffic. Temp drops when back up to speed. Suspect a coolant problem but cannot shift the brass screw on the header tank to check levels. Any ideas ? Can you just fill the expansion tank ?

[nikman]

V41LEY said:

Cider Andy said:

What are the symptoms of the overheating you describe? If the stepper motor is the reason the car is idling too fast it shoudn't cause an overheating problem.

Temperature is 100 plus and wisps of steam visible from the bonnet when in traffic. Temp drops when back up to speed. Suspect a coolant problem but cannot shift the brass screw on the header tank to check levels. Any ideas ? Can you just fill the expansion tank ?

If you found the expansion tank with the blue cap, have you looked inside to see if there's any coolant? If there isn't, it's not as easy as just filling it. But search this forum under "expansion tank" or cooling and you'll find all you need to know. What about the fans - at what temperature are they cutting in? You really should NOT be in traffic at 100 degrees plus indicated like that! Nick.