wizard 13

Hi guys, the wifes gearbox is behaving oddly.

2008 S320 W221 7speed auto.

It have a precautionary gearbox flush (no service history, only 50,000 miles) 2 weeks ago be we find that under 'vigorous acceleration' in either comfort or sport mode the gearbox will make rapid jerky changes between gears and so we have to ease off the peddle.

Under normal driving the gear change is ultra smooth without issues, except under vigorous acceleration.

Any ideas anyone on the cause? I serviced the car couple of months ago. Thanks guys

BOTUS

these gearboxes have a fairly checkered history and do not change well.
they need a fluid and filter change around 5 years max and every 37k miles
then the usual failures come in from 7 years of life

electro plate speed sensor a 10 cents device, dies and its 1k repair although so common you might get it done for 600 these days. Its coded to the car and officialy only Main Merc dealers can fit the part
when trans fluid is left in to long on early cars it causes further fun, the metal and debris runs round ripping seals and o rings to bits and causes conductivity issues it shouldn't
often you need to look at fill rates to see if it takes to long to apply clutches... either travelling too far or oil seeping past worn seals on the actuators.
the TC dies, the lock up clutch fails particularly with dirty trans fluid
some mercs the trans cooler was made wrong and the engine coolant leaks in to the gearbox and trashes everything

you need to take to someone experienced with the right gear to check it out and read fault codes and check transmission adaptions

wizard 13

Apparently the wife floored twice the other day and it only happened on the one occasion so its not every single time.

I will plug in my code reader soon, the reason I havent already done so is because nothing comes up on the dash.

BOTUS

unless a posh code reader its unlikely it will pull codes from the gearbox... expect to see lots of fun, most are just junk where it had a moment and a key on off cycle meant it got over itself
mines thrown gearbox codes randomly for 4 years, sometimes they come back in 3 month but it works ok,others they can vanish for 6 months

occasionally (3 times in 5 years) I need to use steering wheel buttons to make it change up.... but then I see this on others,so without wishing to upset people... these are not good boxes,

joseluu

Apart from listening to the harbingers of doom, you can try a gearbox reset:

wizard 13

Thanks you.

chriswhv6

joseluu would you happen to a vid or know the difference with the procedure if your vehicle isn't fitted with the KEYLESS GO system?
Having issues with my transmission, i attempted once to do a reset but i have no idea if i did it successfully or not

joseluu

I think it should be the same, but with the movement of the key in the hole instead of pushing the button. The steps are the same.

chriswhv6

Thanks for the reply.
I guess when using the key theres 3 positions: O (key inserted only) 1 (one click for accessories) 2 (two clicks all dash lights on).

So would this be correct to do?
Insert key and turn to position 2.
Press down all the way on the gas pedal for 10 seconds.
Now for this part when it says turn off the key would you turn it back to the 1 or the O position? Then release pedal.

BOTUS

that procedure is a total waste of time, its a pointless reset on a hair brained attempt to change gear to suit your driving style

within 3 miles it will have adapted to suite the way you are driving... (note this is a gear change point adaption) and not anything to do with real adaptions where the ecu compares how thing happened, to how they should have happened and attempts to compensate to suit wear tear or bad manufacturing.

the whole idea a chip with the brain power of a dead ant, can perceive the road and weather conditions ahead and your ability to drive or not and then make sensible choices about changing gear at the right time is an utter joke....

joseluu

Again, you can prepare for apocalipsis or invest two minutes in performing a procedure which is recommended by the manufacturer. It’s up to you...

BOTUS

you are totally wasting the guys time... and giving completely false hope. it can't help resolve a worn components inside the box

wizard 13

I bought the car for the wife last christmas and has been used purely as a CEO limousine in London by a Japanese firm so the driving style is going to be somewhat different to the wifes, so a reset cannot do it any harm.

joseluu

It is better to listen to someone who says that in 7 years the transmission melts. Well, mine is 10 years old and works flawlessly.

If you want to save two minutes, it’s your call.

BOTUS

CONTINENTAL 7G-TRONIC (722.9) fault codes



•Y3/8N1 – Turbine speed sensor

•P0717 – The signal from component Y3/8n1 (Turbine speed sensor (VGS)) is not available

•P0718 – Component Y3/8n1 (Turbine speed sensor (VGS)) is defective

•Y3/8N2 – Internal speed sensor

•P2200 – The signal from component Y3/8n2 (Internal speed sensor (VGS)) in not available

•P2201 – Component Y3/8n2 (Internal speed sensor (VGS)) is defective

•P2767 – The signal from component Y3/8n2 (Internal speed sensor (VGS)) in not available

•P2768 – Component Y3/8n2 (Internal speed sensor (VGS)) is defective Other internal speed sensor error codes: P2204, P2205, P2206, P2207

•Y3/8N3 – Output speed sensor

•P0722 – Output Speed Sensor No Signal

•P0723 – Output Speed Sensor (VGS) is defective

•Y3/8S1 – Transmission range sensor

•P0705 – Transmission Range Sensor Circuit Malfunction

•P2716 – Pressure Control Solenoid “D” Electrical

Common problems
•P0705 - Transmission Range Sensor (TRS) Circuit Malfunction
•RPM sensor faults - Fault codes: 0717, 0718, 0722, 0723, 2200, 2201, 2204, 2205, 2206, 2207, 2767, 2768; transmission in limp-home mode (occasionally)

wizard 13

Turns out it was the boost pressure sensor causing the car to bunny hop under hard acceleration.

joseluu

So, nothing exploded after all?