Upshift delay fault, E220 W124

[bubble124]

Hi, this is my first post on the site & am hoping someone can help. My upshift delay has ceased to work. It would previously always work particularly from 3rd to 4th shift (auto obviously).

Everything I've ever read about this says that it delays upshift when cold in order to heat the catalyst quicker. However, I found that it would delay the shift everytime you would start the engine, regardless of engine temperature, even if you turned the engine off and started it immediately.

Anyway, back to the original fault. It no longer works. I've tested the vacuum going from the switchover valve behind the brake servo & still no improvement. I don't think it's avacuum fault but electrical.

Can anyone tell me if the switchover valve is controlled by a relay, and if so where is it. I can tell you it's not in the fuse box OR in the relay compartment behind that. The transmission otherwise performs as it should.

E220 W124,
722.4 four speed auto.
M111 engine

Any help would be appreciated

bubble124

 

[Will]

Hi and welcome

Silly question - but does your car do this all of the time, or just for a short period after first starting?

I'm wondering if the delayed upshift is called for when temp = ≤ X upon starting, hence delayed upshift for Y seconds (or until pre-determined temp is reached?). Could a faulty coolant temperature sensor, or similar, therefore fool the car into thinking that it's running from a cold start always?

Other things that come to mind:

Have you tried the gearbox in both 'S' and 'E' modes? Any difference?
Have you checked the fluid level? When was the fluid last replaced?
Does your model have a kickdown cable (I'm guessing it should, being the 4-speed type?) If so, has the adjustment been checked?

I take it the shifting up problem is present in all gears? Not just in 3rd to 4th - because I would be tempted to check the adjustment/function of the selector mechanism itself and linkages.

Out of interest, what's the mileage/history of the car? Is this fault permanently present or intermittent? How long has it been happening for?

Best of luck,

Will

 

[bolide]

I haven't driven a 220 from cold for a while but on 280s the car holds 1st to about 3000 rpm then shifts other gears normally till it's up to temp

If your box is (or was) delaying the 3/4 shift I would suggest it may not not a cold-start mechanism but something else

I'd check the ATF level and check the adjustment of the kickdown cable. I suspect it may be too tight

Nick Froome
www.w124.co.uk

 

[Ian B Walker]

I haven't driven a 220 from cold for a while but on 280s the car holds 1st to about 3000 rpm then shifts other gears normally till it's up to temp

If your box is (or was) delaying the 3/4 shift I would suggest it may not not a cold-start mechanism but something else

I'd check the ATF level and check the adjustment of the kickdown cable. I suspect it may be too tight

Nick Froome
www.w124.co.uk

I would go along with this too. Wonders if the ATF and filter been changed in the last two years?

 

[bubble124]

Thanks for the reply Will. Firstly, the cold starts are always perfect, so I've no reason to suspect the coolant temp. sensor. E & S mode work as they should, i.e. at full throttle (not to be confused with kickdown) S holds each gear to almost red line & E allows them to change up at approx. 4000 rpm.
The car does have a kickdown cable, but it's really a control pressure cable. The kickdowns are invoked by the electrical kickdown switch on the pedal.
The car use to delay the shift from 3rd to 4th, but I never noticed it between other gears.
I've owned the car for 17 months but tis fault only started about a month ago. It has done 117,000 miles, the trans. fluid level is correct & clean but I don't know when it was last changed.
Incidentally, I am a qualified mechanic but that's not what I do now for a living.
Hope this helps some more.

 

[bubble124]

To bolide & Nick Froome,

Thanks for you replies guys. See my reply addressed to Will for more info.

Appreciate your help.

bubble124

 

[Ian B Walker]

I understand you are a trained mechanic and please forgive me if I am doing a "granny sucking eggs" thing. When checking the ATF the engine should be hot and running when you dip the box. Offence not intended but I have come across this before from other trained mechanics.

 

[bubble124]

To Ian B Walker, thanks for the reply. No I'm not at all offended if someone tells me how to do something. After all, there may be procedures that I'm not aware of.

However, I know that the trans. fluid should be checked hot, & I shall check it again in the next couple of days.

What I was really looking to discover was if the switchover valve behind the brake servo was controlled by a relay, as I have since tested the wiring to it & there doesn't appear to be any current going to it, whether the car is hot or cold.

The switcover valve that is by the left hand front suspension top mounting is working fine. This is the one that is operated by the E,S switch by the transmission selector & therefore controls full throttle upshift points.

Any help would be appreciated.

Thanks, bubble124

 

[Will]

What I was really looking to discover was if the switchover valve behind the brake servo was controlled by a relay, as I have since tested the wiring to it & there doesn't appear to be any current going to it, whether the car is hot or cold.

Hi there,

I'm not particularly familiar with this part - could you describe at what condition you would expect to see this valve energised?

I would have assumed that the vacuum (and whatever valve is operated by vacuum from throttle), kickdown switch and E/S switch position would control most of the shifts.

I've never needed to look into this personally, but it's interesting to know all the same

It's probably worth doing the filter and ATF anyway IMHO if you've had it 17 months and have no idea when it was last done. I believe you can use regular Dexron type ATF in the older 4-speed autos (new MB 5-speed boxes need a slightly more specialist fluid (expensive..) )

Will

 

[bolide]

You don't need to push the throttle to the floor to make a W124 kickdown. It's controlled by the cable

The kickdown switch (under the throttle pedal) disengages the aircon compressor on diesel cars - not sure what it does on other models. Most owners don't even know it's there

Nick Froome
www.w124.co.uk

 

[SilverSaloon]

You don't need to push the throttle to the floor to make a W124 kickdown. It's controlled by the cable

The kickdown switch (under the throttle pedal) disengages the aircon compressor on diesel cars - not sure what it does on other models. Most owners don't even know it's there

Nick Froome
www.w124.co.uk

i never knew that the kickdown swicth disengages the aircon. Does this mean that if i have the aircon ON and i want all the power i can get (ie overtaking etc) - i can kickdown to switch it off for the manouver, and it will come back on afterwards???

 

[Buggerlugs]

Hi Bubble,

From the info I have, the switchover valve is activated directly by a voltage (Probably B+) from pin 42 of the ECM. As a general guide, it's active during the warmup phase between 0-60 deg. C.

And just to clarify some other points, the upshift points and the kickdown is controlled in 2 ways, the main influence is the pressure control cable which can force a kickdown depending on throttle angle versus roadspeed, also I can assure you that the kickdown switch when working properly will force a downshift as it directly activates a solenoid on the rear of the gearbox. The shift feel and overlap is controlled by the vacuum system working on the vacuum modulator on the side of the gearbox, a sort of analogue load sensing mechanism.

HTH and NB..........E&OE

 

[bolide]

i never knew that the kickdown swicth disengages the aircon. Does this mean that if i have the aircon ON and i want all the power i can get (ie overtaking etc) - i can kickdown to switch it off for the manouver, and it will come back on afterwards???

Yes

I imagine this modification came about soon after the test driver of a fully-loaded E300 Diesel attempted his first overtaking manoeuvre...

Nick Froome
www.w124.co.uk

 

[Number_Cruncher]

>>i never knew that the kickdown swicth disengages the aircon.

I'm not too sure it does - or more precisely that it does so alone. The microswitch on the injector pump also can cut the AC compressor at high throttle openings, as well as changing the EGR behaviour.

 

[bubble124]

Hi Bubble,

From the info I have, the switchover valve is activated directly by a voltage (Probably B+) from pin 42 of the ECM. As a general guide, it's active during the warmup phase between 0-60 deg. C.

And just to clarify some other points, the upshift points and the kickdown is controlled in 2 ways, the main influence is the pressure control cable which can force a kickdown depending on throttle angle versus roadspeed, also I can assure you that the kickdown switch when working properly will force a downshift as it directly activates a solenoid on the rear of the gearbox. The shift feel and overlap is controlled by the vacuum system working on the vacuum modulator on the side of the gearbox, a sort of analogue load sensing mechanism.

HTH and NB..........E&OE

Hi buggerlugs,

Thanks for the reply. I think you have given me the answer that I suspected. That is, that the valve behind the brake servo is controlled by the ECM. I shall therefore be looking into the problem on that basis.

One thing though, the upshift delay function is designed to allow a quicker warm up for the catalyst, that's understood. However, when mine USED to work it did so after every start up (cranking) irrespective of the temperature or the length of time turned off. For example, at normal operating temp. & normal driving I could stop the car on the side of the road, turn off the engine, start it up straight away, pull off & I would get a delayed upshift even though the car was NOT cold. Now that is strange.

BTW, thanks for the kickdown info. That's working just fine on my car. As I understand it, the kickdown switch, when activated, overrides any vacuum influenced downshifts, e.g. E or S settings of the switch.

Anyway, appreciate info. about ECM.

bubble124

 

[Dieselman]

One thing though, the upshift delay function is designed to allow a quicker warm up for the catalyst, that's understood. However, when mine USED to work it did so after every start up (cranking) irrespective of the temperature or the length of time turned off. For example, at normal operating temp. & normal driving I could stop the car on the side of the road, turn off the engine, start it up straight away, pull off & I would get a delayed upshift even though the car was NOT cold. Now that is strange.

It may be the temperature sensor is faulty.

 

[Buggerlugs]

Bubble,

I can't account for the upshift delay when the engine is hot, after digging a bit further, on later cars, ie; just prior to the introduction of the 722.6xx gearbox, the delay valve was on the front/side of the gearbox and acted directly on govenor pressure, as opposed to yours which acts on the same valve as the ES switch and therefore will affect all shifts. Also the upshift delay on the later cars is confined to the 2-3 shift only and is active in the 0-60 deg range, the time of operation is dependent on the engine temp at the time of ignition and should last between 60-80 seconds, but is only active up to 60 deg. So it's conceivable that on yours that the delay time is simply activated at every ignition cycle for a fixed period.

As for the kickdown switch, yep, that's the "Boss" of the kickdown function and overrides everything.