Gearbox not changing up ...

[Howard]

Occasionally when i boot the car away from a standing start , the gearbox drops down ( kickdown ) but then won't change up ...

Goes all the way to the redline and just won't change up a gear , take your foot off the gas and let the revs die , nothing , even stopping and starting again won't sort it. You have to stop , put the car in park , turn the car off , and restart and it will be fine again .

Any ideas ?

It only does it when you really put your foot down , you can give it 90% off a standing start and it is fine , but give it the beans and it doesn't seem to like it .

You can kick it down when you are moving , say to overtake , and it is fine , but from a standing start , it won't go up ...

Car is a 99 CLK 320 by the way.

Any advice gratefully recieved .

H

 

[Dieselman]

Any codes.?
I'd be inclined to say MAF but not sure without codes. What's happening is that the gearbox is selecting limp home mode so holding the last good gear.

 

[Howard]

Hmmm ...

How would i get the codes ? take it to a dealer ?

Would it start working again after a turn off / restart ?

 

[jaymanek]

yes the MAF is something that generally clears itself upon a restart... i agree that you need the codes read.. shame you didnt know about this last sunday!

 

[Howard]

Man .....

 

[jaymanek]

just dont spoon it at the lights and youll be ok!

 

[Howard]

Ha Ha !!

Its so hard not to .... remember i've come from a 2.3 to a 3.2

It's still a novelty .... my inner chav comes out ...

 

[Howard]

Think it might be an idea to give the MAS a clean ?

Can anyone point me in the right direction of the HOWTO please ?

 

[jaymanek]

dont bother mate, ive tried cleaning them once or twice and ended up breaking it, very delicate.. i think those V6 ones are pushing £100 for a Bosch one from Euro..

Not only have you come from a 2.3 to a 3.2, youve come from a 80's eight valve four pot to a fantastic 24 valve V6 which is still the basis for all the petrol engines being produced today.

That engine is my favourite out of all the mass produced ones... even if it does squeek a little

 

[74merc]

Not being pedantic, but isn't it an 18 valve V6?

 

[jaymanek]

probably, is it three valves per cylinder? cant remember now!

 

[74merc]

My C280's engine is a 3 valve per cylinder, twin spark. Doesn't sound right though - 18 valve...

 

[jaymanek]

I think it is actually, two intake and one exhaust valve... they didnt make the same mistake as the 300-24 i.e trying to cram too many valves in which leads to premature gasket failure...

 

[cmarkod]

I did this a couple of times when I first got my car and then realised that I was resting my hand on the gear lever and nudging it slightly and thus selecting 1st gear. Having changed from manual to automatic I was used to resting my hand on the gearstick but have cnaged this behaviour now!

 

[grober]

I think it is actually, two intake and one exhaust valve... they didnt make the same mistake as the 300-24 i.e trying to cram too many valves in which leads to premature gasket failure...

The 3 valve heads on these V6 AND V8 engines was principally to reduce emissions AFAIK. They meant a slight reduction in breathing efficiency compared to the older 4 valve designs unfortunately.
Howard the Pierburg inserts are cheaper than the entire MAF unit. You can get them from GSF.
http://mbclub.co.uk/forums/showthread.php?t=25426

 

[Howard]

I don't have the 'nudge' change on mine ...

Dad does on his CLK 430 though , so i know eactly what you mean .

When i get back off holiday , i'll have a day out to Ollys and get the codes read .