Engine Reving too high on start up and drive off

[Fais]

Hi all

My sl320 (1995 - Straight 6) is giving me some trouble.

The Engine starts quite loudly when i start the car in the morning. As i drive off, the car sticks in the low gears and takes time to shift gear.

However, as the car warms up, gear changing becomes smooth again. In the summer this only happened when i first started the car in the morning, however, now it seems to happen every time i start the car.

I've only had the car since May 2004.

Any ideas on how to approach this problem?

Thanks!

 

[se97mlm]

My 98 C240 does this also, it's a "feature" to warm up the cat more quickly thus making it work as soon as possible to help pass emissions legislation.

You will notice this more in colder weather as this program runs longer than in the hot weather due to the longer warm up time.

On mine, it holds on to each gear up to 2500 or 3000 rpm when cold eith the lightest throttle opening. This falls to about 1500 - 2000 rpm change ups after 5 minutes.

You can get the feature diasabled at the dealer, but they make warnings about voiding the cat warranty. This is obviously not an issue on our age cars though.

Most annoying, the car eats fuel if you do lots of cold starts because of this.

 

[Fais]

thanks for the reply se97mlm.

That's my main prob - car eating fuel. I do lots of short trips over the course of the day, making every start a 'cold start'. The cars revs to 3500rpm on each gear at start up. Any idea whether this can be regulated to 3000rpm - so it doesn't damage the cat too much and doesn't drink so much fuel.

 

[guydewdney]

how long between starts? is the engine completely cold at the next re-start?

I know an SL is a nice car - but arnt you wasting it for 'short journeys' - or is it seeing clients / customers and you need to portray the right impression? - if not - get a 1 - 1.6 litre escort or somthing.. be cheaper in the long run...

 

[PJH]

My W124 280E gear changes
1st/2nd @ 2,500 rpm
2nd/3rd @ 3,000 rpm
3rd/4th same as when warm

This high revving lasts between 100 yards (hot summer's day) to about
half a mile on a cold winter's night.

You could double check with DorianT as he has the same model.

 

[Ian B Walker]

Might be an idea to check the auto transmission fluid too. Old fluid does strange things

 

[fuzzer]

sounds normal for a new 5 speed auto.

I tip my box up when its cold to save fuel , but you won't be able to do that

just accelerate and then ease off sharply from the throttle , thats how i used to make my non tip box change down

 

[DITTRICH]

...on my w202 c230k 5 speed auto. I am lucky enough to have a clear stretch of road immediately from startup (at 6.00am that is). So I just briskly accelerate until I drop down into 5th at about 40mph. It takes about 100m to do this. I then back off the 35 or so and cruise at 1,250rpm. 1st-2nd at 2,500rpm , 2nd-3rd at 3,000 rpm , 3rd-4th at 2,500rpm and then it just slips down into 5th to arrive at 1,500rpm. Needles to say the temp gauge is still way down at this stage and takes 2-3 minutes to reach 85 where it stays.
Rgds
Les

 

[glojo]

I accept that I have a diesel, but a diesel engine takes longer to warm up, and the 211 has catalytic converters. My vehicle certainly does NOT run fast until warm.

Is this 'high revving' common amongst everyone within the mentioned class of vehicles? I ask this because on old vehicles with automatic chokes this was quite a common problem. Could your symptom be a cold start adjustment problem?

Regards,
John

 

[se97mlm]

The quick warm up feature is not needed on a Diesel car.

Diesels do not have a choke feature which is beastly for emissions. The idea is to get the cat to it's working temp as soon as possible in the choking period, as the standard european urban cycle tests start from a cold engine.

It's definately supposed to do it, not a fault. ON the older non-electronic gearboxes there is a cold start solenoid on the box which is used to change up later when cold. The later 722.6 boxes do it with the software mapping. I have a Mercedes technical CDrom which explains this all quite nicely.

I believe that the 320 engine concerned is of the M111 type, which being ECU controlled does not have any form of idle adjustment (I think!)

 

[glojo]

The quick warm up feature is not needed on a Diesel car.

Diesels do not have a choke feature which is beastly for emissions. The idea is to get the cat to it's working temp as soon as possible in the choking period, as the standard european urban cycle tests start from a cold engine.

It's definately supposed to do it, not a fault. ON the older non-electronic gearboxes there is a cold start solenoid on the box which is used to change up later when cold. The later 722.6 boxes do it with the software mapping. I have a Mercedes technical CDrom which explains this all quite nicely.

I believe that the 320 engine concerned is of the M111 type, which being ECU controlled does not have any form of idle adjustment (I think!)

Thanks for the info.
No doubt you are also aware that diesels have a 'pre-glow' which 'warms' the engine prior to starting.

How does this solenoid work in very slow moving traffic?

Thanks very much for the input.
Regards,
John

 

[V12]

This particular 320 is an M104 engine, The M111 is the 16v 4 cylinder from 1992 upwards...
But being the later M104 with no distributor and coil packs in the rocker cover, it is all electronically controlled/adjusted...

Ricky