Someone correct me if I'm wrong, but I believe the upshift delay exists to help protect the transmission from undue wear. Disabling it might give you some short term convenience, but at what expense in the long run?

 

Thom_7 is wrong. The upshift delay is to heat up the catalyst for emission reasons. Once the car hits a certain temperature, the delay disappears.

 

Joe's right.

Replace the coolant and coolant thermostat every 2 years and 4 years, respectively.

Faster warm ups, better gas mileage, cleaner oil.

James Combs
Salt Lake City, Utah USA
1997 S320, 120,370 miles (yes, I'm going to bed!)

 

I thought it was to warm up the tranny oil.. Cause one day I let my car warm up for 5 mins (should've been enough time for the kat to warm up) and once I pulled out to the road, I still had the delay..

 

I know that that option is so annoying that it makes you think there is something wrong with the transmission, I didn't care for heat up period for the cats or anything ,I just got rid of it & was extremely happy ever after ,check the link below ,that is what you need to do to get rid of that .
Every member above me is right about this ,its up to you know . :thumbsup:

http://www.benzworld.org/forums/w140-s-class/1486196-ecu-chip-installation.html

 

Yeah I hate it. I had an Audi POS and this was one of the many reasons I sold it, I have another car that still has a shift delay but it is very subtle, whereas the Audi and the W140 have a very aggressive shift delay.

Too many engine revs with cold oil wears it out faster and can cause leaks early. Bringing up engine temp slowly by gradually increasing load and revs is much nicer, and nicer on the gearbox too. The environment will appreciate less worn out engines too but the stupid emission rules are very short sighted.

Do you have an actual brand of chip you would recommend? Ebay links in that other thread are a bit outdated.

Is there another way without resorting to a chip?

 

A suggestion

Let me add my name to the list of annoyed by this "feature". From a little investigation it seems that it might be quite easy to defeat this shift delay, for my 722.5 at least. The attached extract from a file I found somewhere shows the operation of this system.

I suggest that simply disconnecting the electrical connector to the shift point retard solenoid valve will do the trick.

Any comments? Anybody willing to try?

 

Getting interesting. Do you have the "A/T article in Transmission Servicing section" referred to at the bottom of that PDF? It hints that there might be some adjustments to be made, hopefully some "wrong" adjustments will disregard whatever the ECU is demanding without any codes being thrown.

 

Sorry, should have posted the link to the complete file: http://w126.pp.ru/akp722.pdf‎

It applies to 722.3, 722.4 and 722.5 transmissions and will not apply to all W140's.

 

Something to try

Great article attached which suggests the cold upshift delay can be deleted by simply disconnecting the wire to solenoid Y 3/2.

Anyone willing to try and report back?

 

Thanks, nice find! I had a quick look at the pdf:

"Mercedes used two different ways to control the Upshift Delay System. The first method we’ll discuss works closely with the governor system; we’ll refer to this system as the Governor Type Upshift Delay System. A second system that we’ll discuss in depth in a later article operates based on engine vacuum levels."

Mine has the 2nd type vacuum level system. I did a quick dig around for the 2nd article with no luck. My box is still out of the car in bits, but when it goes back in I'll be doing some experiments with various removed and blocked vacuum lines and see what happens.

 

Is this what you need? See attached.

 

Yes, you supplied a link to that PDF earlier in the thread, thanks again. I just don't know if I can simply bypass the Shift Point Retard Switchover Valve (item no. 5 in fig. 3 on page 6) or precisely what is required to do the job.

 

Joe,

I thought of doing the same, but I just work on so many cars, and just deal with it only when the temperature drops below 10C(50F)...I would interrupt the transmission overload switch, but these transmissions vary from the established documentation.

Martin

 

This is where my research is taking me: For transmissions that are vacuum-controlled, like my 1992 300SE 722.5, the governor-type upshift delay does not apply. Instead the Shift Point Retard Switchover Valve (Y3/3) is activated by the ECU to achieve the same result. Figure 3 in my previous attachment shows this, and the insert figure shows the governor configuration. The document is confusing because it does not make clear that there are two very different designs.

http://www.benzworld.org/forums/w140-s-class/1370153-upshift-delay-switchover-valve-location.html led me to the valve, mounted by itself on a small bracket in the front left side of the engine bay, under a cover and next to the A/C fill port. I unplugged the electrical connector. Success! I no longer have the delayed cold upshift.

Failure! Check engine light came on. Maybe I should bypass the vacuum lines around the valve instead?

 

The answer appears to be simply disconnecting the vacuum line from Y3/3 to the transmission.

Mercedes Benz Workshop Manuals > 300SE (140.032) L6-3.2L (104.990) (1992) > Transmission and Drivetrain > Automatic Transmission/Transaxle > Shift Solenoid, A/T > Component Information > Technical Service Bulletins > Page 5350

 

Nugent,

Well done! thank you for the information. I just never bothered to chase it down, but the cold climate people suffer from this problem more..

Thank you,

Martin

 

Yes, disconnecting vacuum line will disable delay. You may get a CEL depending I guess on the LH module software revision. My 92 600SEL works just fine and no CEL, but 92 500E, later production than 600SEL, gets CEL after about a week or so. Also need to plug the line to the engine to prevent vacuum leak when valve is activated by the ECU.

 

Great info people, this will save me a lot of time!

 

Disconnecting the vacuum line will throw a code. I kept getting a code in my '96 S320 for the upshift delay and found that it was due to a vacuum line disconnected. Once I reconnected, the code hasn't come back and the upshift delay is now functioning as designed.

If you don't mind a check engine light and you don't have to deal with emissions testing, then removal of the vacuum will work. It will not pass emissions with it deleted as the upshift delay is a part of the emission control system.

 

Hmmm, maybe the system knows when the cats takes longer than usual to warm up.

 

Continuing... I disconnected and plugged the vacuum line to Y3/3, which achieved my aim. However, as others predicted, the CEL comes on after a few starts. The Diagnostic Module code is #19 Injector open or short circuit or emission control system adaptation at limit.

Is there any way to trick this?

 

This is a code for adaptations out of range and unrelated to the up-shift delay.

 

Unrelated system but it obviously picks up the effects of up-shift delay delete.

Well, I cleared the code, reconnected the vacuum and everything is back to the way it was, together with the cold shift delay. The code has not reappeared.

I had plugged the vacuum source line back to the engine, so I don't think that is what triggered the code. So as Joe-Trojan says, it seems to be registering indirectly, but I don't know how. Therefore I don't know how to fool it.

 

Unrelated system but it obviously picks up the effects of up-shift delay delete.

 

The only possible explanation I can come up with is that the wrong side of the vacuum line got plugged and engine sucks air. This may get adaptation on the limit. I was getting DTC26 for the upshift delay.

 

Why doesn't someone just ask Mercedes Benz why the shifting "thingie" is set up the way it is, i.e., what is it supposed to accomplish, and what potential damage might be caused by messing with it? If they don't know, we might as well take a poll on the forum and hope for the best.
Hemersam