gearbox problem on C43 AMG

[KLP 92]

My cousin has recently acquired a 1999 C43 AMG. I took the car for a spin and noted that on full acceleration when the box changed from 1st gear to second it firstly cut power at 5700revs then slighlty violently changed to 2nd gear. When changing from 2nd gear to 3rd gear under full acceleration the box refuses to change up a gear unless you lift off the accelerator slightly. It does the same when changing from 3rd to 4th at the similar rev band. It seems the cars sits there bouncing on some sort of limitier and won't accelerate any more but will not gear will not shift up a gear either. When you kick down on a motorway at 70 mph and it go down to 3rd gear its slightly violent in the change. I had the gearbox oil and filter changed for him but this didn't rectify the problem. The car has been on the computer and there are no faults at all showing up. Everything was reset but still the problem is there.

Its not noticable in "W" mode as the changes happen before 5000-5500 revs. apart from this niggle the box is super smooth and never clonks/slips. The car has 60k on the clock and has FMBSH. The car does not have any lack of power either and pulls like a train. The problem only really happens when you are thrashing it but nevertheless it shouldn't be like that.

I took the car to George Fraser's and he's stumped with what it could be. He's going to have a gearbox specialist come down and investigate what it could be.

Does anyone have any ideas?

 

[Anders]

I had a similar problem on my C43, which I believe was rectified by adding 1 litre of gearbox oil, which was lacking after MB initially changed it.

Also, I seem to remember from other threads that the MAF (oh no, not that word again) could somehow be to blame for it, but I never really understood why.

Sorry, this is a bit vague...

 

[d1st]

I have a very similar problem on my w202 180 auto. When changing from 1st to 2nd gear, there is a slight jolt but I can prevent this by coming off the gas just before it's about to change. Once it's in 2nd the next changes are quite smooth but not perfect. I did read in my manual that it says you should come off the gas when you need the next gear which does certainly make the gear changes happen when you want it.
I don't know if it needs to be looked at or not and it's not worth me spending over a bag of sand for a gearbox repair but then I don't have a C43 AMG!

 

[R2D2]

I think all w202s get this sometimes. Change the gearbox oil and have the adaptive memory reset and I believe it problem will go!

 

[GrahamC230K]

I have read about C43's hitting the limiter in 1st before. I am sure it's a know issue. Can't help but suggest you dig furhter on the forums etc.

 

[Mambo]

Had the same problem on mine, seemed to fix itself once the MAF was changed

 

[C240Sport97]

roughly the same sort of thing was happening with the gearchanges on my C240 when the MAS/MAF was on its way out. After it changed, no problem.

Has the C43 had its MAS/MAF changed before? This fault should show on the diagostic computer though

 

[Shude]

My gearbox had logged two faults last time the car was serviced, both times were the diff lock, the servicing guy said that it might have been the jolt I was getting sometimes when it shifted.

 

[Steve_Perry]

I got violent up-shifts, usually 1 to 2 or 2 to 3, when my MAS was starting to fail before it totally gave up the ghost. When it got a little worse just before the end the gearbox would hold gears and refuse to change up unless one lifted the throttle. e.g. flooring the accelerator at 70 resulted in the car dropping a gear (or two??) and then heading towards 85mph and sticking at that speed with no change up to the nexxt gear.

After it was changed all was well and silky smooth gear changes returned.

S.

 

[KLP 92]

The gearbox oil was replaced 2 days ago now. Its on the full mark and has been checked again. There are NO faults at all on the ECU. The ECU has been reset and rechecked again after a test drive. Still no faults on the ECU.
According to George Fraser as far as he can see there seems to be no issues witht the box itself as the changes before 5500 revs are perfectly smooth and the problem only seems to arise in "S" mode with full throttle when approaching the 6000 rev mark. If driven with the accerlator nearly fuly pressed but not 100% pressed the gearchanges are fine.

I would definately saw its not normal and something is wrong with it. Was hoping the gearbox oil/filter would rectify this problem but no change. I will speak to George tomorrow and see when he can arrange the specialist to come down and see the car.

 

[McGreggor]

It's the MAF, had the exact same thing on my C43. The ECU doesn't always report a fault for a dodgy MAF, but there are two timings which the ECU can adjust by itself for left & right banks of cylinders. On mine, the ECU had adjusted both to the maximum amount its allowed to do, indicating theres a MAF problem. Change it, and its best to change the air filters too, and the gear change problem will vanish.

 

[Anders]

It's the MAF, had the exact same thing on my C43.

If you don't mind me asking, how much was the MAF for the C43?

 

[KLP 92]

If you don't mind me asking, how much was the MAF for the C43?

quoted by Merc at £240

 

[McGreggor]

It's quite an easy job to do yourself if you fancy saving an hours labour. The MAF is near the bulkhead under the airboxes which just pull off with a sharp tug. The airboxes come apart to change the filters easy enough, can't remember if it was a star drive needed or not, I think just a phillips screwdriver. The old MAF will easy enough to spot once you have the replacement MAF to go by, it is held in by a strap/clamp that goes round its girth. I got the whole job done inside half and hour.

 

[KLP 92]

As always you were all right.
Quick trip to George Frasers in the morning and a new MAF the problem has gone! The performance has increased noticably and the gearchanges are razor quick!
Many thanks! And as me and George go back a long way, £100 was the damage!