Quote:
Originally Posted by john.wigley
Hi Adam, Is this a recent phenomenon? If so, might it not be a fault as such, but due to the high ambient temperatures coupled with the load or drag on the transmission when you engage D or R? Most of the automatics that we have owned over the last 30 years have exhibited similar behaviour to a greater or lesser extent.
Regards, John.
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I would tend to agree with John, all auto transmissions have an element of drag due to the torque converter never completely disengaging, in modern (after about 1995) motor cars this is probably ameliorated by a computer adjusting the motor to suit, a 1990 Volvo won't have such a sophisticated system so I don't think a 200 RPM drop when in gear would be unusual. I certainly notice similar in the RB (a 1980 244 with even less control systems).
Is this motor car new to yourself? If not and you are sure it is new behaviour then it may be that one of the separate sensor and control systems on the motor car may have changed.
Good fortune,
Alan
PS. You say:
The only thing that makes the revs behave properly is engaging Drive or Reverse ... but I suspect it will do the same in positions '1' and '2' as well - although obviously proportionately less.
PPS. You say
'The only other thing I can think of is the P/N detection switch on the transmission or whatever it's actually called?'... that would be the starter immobiliser - just test it by trying to start the motor car in any gear (D,R,1,2) - if it won't start then its working properly.