2.5L Shift Points and Down Shifts Questions
 

What RPM does the your 2.5L turbo (W201 and W124) shift under full throttle and in drive? My 87 190D 2.5L turbo used to shift at 4700 rpm and used to downshift properly. Now it shifts at at 4200 and will not downshift correctly. If the car is going 5 mph it will not downshift into 1st (it used to). My bowden is adjusted full tight, I even elongated the slot on the bowden cable linkage to tighted it even more, no difference. I am sure it is supposed to shift at a higher rpm, it pulls easily to 5000 rpm when manually shifted. Anyone had similar issues?

No one has seen this issue or knows what rpm a 2.5L turbo shifts under full throttle?

The cable should not be that tight, mine is alittle loose. What happened to cause the problem?

I am not sure, I had to keep tightening it to keep the shift point up.

Just to rule it out, have you checked the fluid level? When is the last time the fluid was changed along with a filter?

I'd personally start there before tearing into the valvebody or worse.

The fluid and filter have about 3-4K miles on it and old fluid looked good. I have even checked to make sure the IP linkage is opening all the way.

Try searching for 'shift points', members have posted scans of manuals that show the different suggested rpms.

First off, the fluid level and the cable need to be set properly as mentioned.

Tightening the cable will not fix shifting issues. It belongs in one position, anything beyond that will cause downshift issues.

Improper fluid level will also cause shifting issues, like slipping.

cable setting:

tension in the cable should begin when fueling begins or the moment that RPMS increase. The cable should be slack until that point and can be felt by hand.



Trans Fluid:

fully warm the trans by driving over 30 minutes. Fluid level should be checked with the engine running, trans in "P" and on very level ground. The fluid should reach the top mark on the dipstick.

The fluid level is ok, I have checked it a couple if times.

It actually shifts ok now, a little too firm, no slipping. I have moved the cable adjust back and forth without much change. I acts like the cable is too lose.

Delayed shifts can be caused by low vacuum. This would correlate with your downshift clunks and firm shifting.

Inspect the vacuum system for leaks, primarily the vacuum modulator on the trans. and anything else directly tied to that circuit.


I think sometimes people expect these cars to shift like gas cars... we are so used to them here. Diesels have high torque and do not need to start out in first gear every time you accelerate... this is an efficiency feature. The car was intended to start in second gear when not heavily accelerating. (or pulling a large load)

I actually bypassed the blue amplifier because it was slipping during slow speed downshifts sometimes. I have checked the modulator, it holds a vacuum and the vacuum to the modulator goes to 0 when full throttle. The trans acts (upshift and downshift) as if the throttle is @ 80% even though it is @ 100%. The only issue is the low rpm full throttle upshifts and hesitant downshifts.

If the cable is properly set and vacuum is within a reasonable operating range, then the last resort before installing the shift kit is:

Increasing the modulator pressure incrementally to a point where the weakest shifts become quite firm.

Then, adjusting the vacuum to smooth everything out

re-installing the vacuum amplifier will increase your success during this procedure.

In order to shift later bowden cable need be losened.When you tighten cable actualy it is shifting early.I just fixed this problem on my car.

I agree.

When I first started on my w124 300D's transmission I removed the vacuum amplifier. When I finally got everything to work right I needed to return it.

I think you have it backwards, tightening the cable makes it shift later. All I am wanting to do it get the trans to shift at a higher rpm and to downshift at a higher mph. From what I have read at full throttle the only thing that controls the shift point it the bowden cable and the modulator controls the shift quality. There is a kickdown switch as well, I have not figured out if it has anything to do with the shift point (which I still have not found what it whould be, 4500? 5000?). If I can get this fixed then I will work on the shift quality.