I have a lexus is 250 with a tiptronic auto box when im coming downhill the car is hunting/jerking and never done it before.the gearbox is smooth but when you drive on the highway for a long time and

You need the powertrain control module/processor checked for fault codes

this sounds like the gearbox is not hearing what the engine is telling it,,,its all through switches,,if one is not working right the gearbox gets lost! and dont know when or what gear to be in

It could be the thickness/condition of the fluid and if its been changed recently is it the correct fluid,as Mitsubishis are known to be fussy about the fluid they run,check the color ,it needs to be a reddish pink,if its brownish it needs to be cheanged/flushed.Of course check the level carefully,this should help sort the issue!

You say up and down hill. Does it work OK on the flat? If so, there is a sensor for detecting the fact that you are going downhill and this holds the gear you are in when in auto mode to achieve engine braking. I believe failure of this should throw a fault code in the gearbox control unit if this is the case. It could be that the failure of this sensor is inhibiting tiptronic mode, but I can't be sure. Either way, get the dealer to read the codes from the gearbox, not just take it up the road and say they can't replicate the fault.

At the bottom of the automatic gearbox (tiptronic) you will find 2 threaded plugs on below surface. First (in front of the car) is for emptying, and second is for filling up. Tightening torque is 24 Nm. Please Rate my Response! Thanks!

the problem sounds like mine i had all the fluid and filter in gearbox changed it sorted the problem out
micky

Hi there. Although the Dealer has changed the oil, did they do a 'Stall Test' whilst the gearbox was cold and again when at normal running temperture? If not, that's what they must do firstly. This will identify whether you have a slipping clutch/s. The Honda autobox also includes what is known as accumulators - these control how each clutch is engaged during acceleration. For example, if you are accelerating slighly/smoothly, you want each gear to be engaged gently and smoothly, whereas, when accelerating hard, you need the gear engaged quickly and hard to aviod clutch slippage. Thus, the fact that you are experiencing a hard engagement might mean that an accumulator/s is seized. If that's the case, it will mean that the autobox will need stripping, cleaning and be checked for worn components. Hope this helps, Scottech.

hi,i'm ck .my audi c5 2.4 model 2001, when put on D while driving, it go to neutral?

I have been having similar problems. The clutch is slipping as thats how you get the variable gears when in full auto, but this is where the problem comes from, some garages (auto gearbox specialists) are now able to fix it. Do not go to Audi as all they do is replace the gearbox (very expensive). There is no quick fix though! Sorry for the bad news!!

have you had any transmission services done yet? like a flush sounds like a sticking solenoid but very hard to say with out looking into it please rate -jeff