Stepper motor

[ciscodisco]

Hi all, I am educating me about Chimaeras with a view to buying (and have gained a lot of info from this forum) so I need to ask some very basic questions.
What is the stepper motor used for?
How many miles do the exhaust cats last for?
Which model has no ABS and no power steering?
I will be back with more questions !!!

[Martin_S]

ciscodisco said:

Hi all, I am educating me about Chimaeras with a view to buying (and have gained a lot of info from this forum) so I need to ask some very basic questions. What is the stepper motor used for? How many miles do the exhaust cats last for? Which model has no ABS and no power steering? I will be back with more questions !!!

1) The stepper motor is a component in the fuel injection system that controls idle speed. Basically, it is a small, motor driven valve that allows air to bypass the closed throttle, thus giving the engine just enough air/fuel mixture to 'breathe' and keep ticking over when the throttle is closed. Dirty or faulty stepper motors will not control this bypass air closely enough, resulting in uneven or erratic idle speeds, rough or uneven low speed running etc.
2) Cat life is dependent upon treatment and engine condition. They don't like being contaminated with raw fuel or oil, so a worn engine or maladjusted fuel injection system can kill them, as can using LRP, genuine leaded petrol or some fuel additives. They are also very brittle and fragile and can be damaged by shocks. Backfires from ignition faults or running out of fuel can destroy them pretty much instantly, as can the thermal shock of running into deep standing water on many cars (not TVR's usually, 'cos the cats are mounted quite high up in the exhaust system and so are out of reach of deep puddles). On the other hand, on a healthy engine and without any other detrimental influences, they can go on a very long time indeed - longer than the rebuild life of a TVR engine, certainly!
3) AFAIK, no TVR has ever been fitted with ABS brakes yet, so you needn't worry about that one, and earlier Griffiths and Chimaera's lack PAS too. Adverts for cars for sale will usually mention PAS if it is fitted, but it became standard on later production models.

[victormeldrew]

Martin S said:

but it became standard on later production models

Is that later models as in Tamora, Tuscan etc, or later model Chims? I thought it just became a "preferred" option, rather than , standard fitment, when more southerners started buying Chims.

[ciscodisco]

Thanks guys, I really appreciate the help.

Ciscodisco