Can anyone explain this initial lag to me?

Geoffps

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When I first start from cold and drive my 2006 SL350 facelift it sets off almost like a manual with a slipping clutch. The speed is slower than the revs suggest it should be. But it only lasts for about 50 metres and thereafter it drives very responsively. I've changed the oil in the engine and automatic transmission.
I can live with it easily but there's obviously something not quite right, does anyone have an idea of what it is?
 

ajlsl600

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clk3202001,sl6002003 with everything regrettably sold ,A class 170cdi auto. NG/TF1800 ML250
Possible issue with tc? Likely something electronic.. lock up valve sticking ?
 

Botus

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your info doesn't give enough info about what you think is a fault.

you should never rip it off the line when cold. so if you are taking it easy, it might just be a catalytic converter heat up sequence ?

many manu with autos in cold weather, hold low gears till either a certain temp, time or distance is covered to help the cat warm up so it works / doesn't get damaged.

I usually hold the revs at 2k for about 2 mins before driving off. With my engine it seldom see's >1700 rpm in a 10 mile drive. Even so, in the cold the car hasn't detected I let the cats really warm up and is silly for a 100m or so

my omega would not change out of first until 2500 rpm was reached, really irritating as the conditions I have you need to thrash the car just to get out for first, my merc is somewhat similar but never sure if revs or distance (but it always gets over itself without reaching >2.3k on my v8, and in a shorter distance than the omega v6)
 
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Geoffps

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I don't try to rip it off the line, I drive from my home drive onto the road and have learnt now to take it easy for 50 metres then it will be normal. I never tried to drive over fast but now I drive very slow initially and that's ok for me because I live in a quiet road but if I lived in a position where I had to drive into flowing traffic I'd have to stay on my drive for a while to warm up before going.
It could well be something to do with the cat warming up as you say, it's just that I doubt that it would have been like this when it was new.
 

Botus

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if its cat warm up - it will have been there from new. the point you make about conditions is similar to me, because I can't get on and drive at a steady 2200 which would be good for the car, its a main reason I do it stationary, I have a number of short sections where the car's holding a gear I don't want and it makes it feel cumbersome... (the omega could do it for a good half mile). My father's E class did it last year for a similar distance (when I'd never detected before). On his, as its a tractor I was even more confused. I started to wonder if it was trying to keep the revs up to get charge in the battery.

lots of owners either never seem to notice the cat warn up cycle, or think it only happens now and then when cold (and accept as a strange glitch).

I think if its been running for some time then the car may not follow the procedure (so if you now illegally ran it on your drive to demist / defrost) thus may not even do it

or if you have the radio loud and are generally preoccupied with something other than driving and not that mechanically au fait, it can go unnoticed.
 
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Botus

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TC= torque converter.... part of the auto transmission, since 1990 most have a solenoid to lock it up for greater efficiency at times... but if its stuck on when it shouldn't, it tends to cause stalling or lower revs and jerky changes. If the TC is trashed then it would rev higher everywhere and never get over itself

Other Auto faults tend to hold on to the gear and make is rev higher, but I don't think its normal to get when cold and not to regularly get over itself the way you explained it.
 
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Geoffps

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The car drives very well except for this fairly minor issue. I think I'll just relax for now and worry more if it gets worse in the future. Thanks for your suggestions and Merry Christmas.
 

Jason63

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I don't know about MB but the ZF gearboxes used in BMW's of the same era do this intentionally. The torque converter intentionally slips until the gearbox oil reaches 35C. This is to warm the gearbox oil and assist getting it into a good operational range as quickly as possible.
 

ajlsl600

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A likely possibility lock up restricted until oil temp at min levels.n if playin up likely the components involved, my money on temp sensor or valve.
Do advise cure.
 

umblecumbuz

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MB auto boxes often hold lower gears when taking off from cold, and this can seem like the affect you describe. Once a short distance has been covered, they begin to work normally. Not many details to go on here. When was the last service? Who by? What mileage has your car covered?

Just a thought - when you say you 'have changed the oil in the transmission.' Was this done by an MB dealer, yourself, or a local garage? In any case, was the correct spec atf used, with the car on level ground, the gearbox up to temperature and the engine running? Was the correct dipstick also used? Was the gearbox filter also changed? If any of these parameters was not checked, you could have incorrect or inadequate fluid in your gearbox.
 

Botus

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just been observing mine in the last few days of cold temps. even after a good few mins holding revs in neutral at 2000rpm:

setting off below say 12C it holds back the up changes for 200 yards
but now below 3C its holding back every change till 2000rpm is reached for up 0.7 of a mile
in the summer that same route would not see the revs over 1400rpm (when going gently letting it warm up)
 

LostKiwi

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Both the 210 and 230 do this in cold weather. As said it's part of the cold weather warm up process.
 
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Geoffps

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Thanks to all for your explanations. I have now accepted that it is this way and I make allowances for it. It's not much of a problem.
My car is a 2006 SL350, I also have a 2001 S600 which starts and drives off with no lag at all so it seems strange that MB made a later car with an inherent fault/peculiarity but c'est la vie.
 

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I story is to never do any harsh driving on any cold engine or gearbox untill fully warm . If you do then get ready for a hefty bill .These cars are heavy, so give then time to do what you expect them to do .
 
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Geoffps

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An update to this thread. I took the car to MB World at Brooklands (main dealer). I told them that they wouldn't experience this fault unless they kept the car overnight because it only happens the first time it's started each day.
They kept it overnight, drove it in the morning and told me that they felt the problem - to reiterate, it revs to whatever extent you put your foot on the throttle but only moves forward at about 5mph then after 50-75 metres it engages and off it goes. It will be fine when it's started up again later in the day. It doesn't matter what the outside temp is, it always behaves in this way when first started.
Their Star computer didn't recognise any fault but the mechanics said it should not do this although they had no idea what was wrong, They recommended a new gearbox for more than £4,000 and charged me £150 for their advice.
I don't plan to put in a new gearbox, if there is something wrong with the gearbox it will always be wrong I think, not just the first start in the morning.
I've had the gearbox oil and filter changed twice by a very good local MB indy (who understands about the temperature etc,), but it hasn't helped. I tried putting a bit more oil in the gearbox to see if it made any difference but it didn't so I took it out again.
It's a 2006 SL350 7G tronic version. It's done 75,200 miles.
Any other suggestions will be appreciated, thank you very much.
 


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