Irresistance
Senior Member
- Joined
- Apr 25, 2009
- Messages
- 786
- Reaction score
- 6
- Location
- Gdansk, Poland
- Your Mercedes
- 2004 W220 320CDI
Hi there,
Been a very long time since I visited these parts - happy to see y'all still around, even with a banner ad for each sub-forum
My trusty old W220 320 CDI (post facelift) has received a reanimation-level servicing last month, as it was in a rather sad state for a while. New air strut, front brakes, shiny new steering rack and indeed a new MB OE power steering pump, bushings on the drive shaft... a whole bunch of TLC. Further gradual rectifications are in the works Despite it's 20 years it still drives like a dream!
However, a significant Freude Am Fahren-damping condition persists... it received two new Delphi ABS sensors on the front wheels as it had been limping in ABS/ESP fault mode for the better part of a year. For good measure, one front wheel bearing was also replaced.
Post-repairs, on ignition, ABS and ESP report no fault, but the moment one starts driving the following happens:
1) Braking more often than not causes the pedal vibration alert, at least a little;
2) Exceeding the speed by, say, 20 MPH will cause the ABS to disengage/show the ABS/ESP error;
and perhaps most confusingly...
3) Above about 18-20MPH the speedo starts to... dance around... up and down... like, when going 60 KM/h it may very wel jump down to 40 KM/h, and anywhere in between. It does not, it appears, ever display a speed higher than the one driven, only dip down to lower ones. Now - one thing that might be of note: When going 25-55 km/h, the digital speedometer (on the central display) joins the needle in its erratic speed reporting... however above about 75-80, it almost never does.
This tells me that:
- the higher the speed, the more frequent the signal;
- above a certain frequency the digital display (which is a bit... "lazy", so to speak) doesn't bother to display the briefly received erroneous speed;
- it would seem the issue is the computer now and then getting the WRONG signal, rather than NO signal;
- therefore - it is a signal error, not a calculation/processing error.
My most competent mechanic has replaced the ABS sensors (and this did eliminate the "at fault from ignition"-condition the car had previously) but is now suggesting it might be the ESP/ABS computer gone bonkers. I trust the man wholeheartedly, but as per above deductions, I have a measure of doubt about this claim. It's not... expensive to "prove" - a computer can be had for 30 quid and for another, what 40? I can have it reprogrammed by some Dude With A STAR-Laptop.
But it just does not seem to make sese the computer would suddenly kick ze proverbial bucket, and the nature of the issue tentatively suggests other possibilities may be at play. Electrical wiring? Corroded contacts? Warped "funny little metal disk with slits for sensor"...?
What sayeth ye, oh online Oracle of Wisdom of all things Mercedes...?
Also, in another part of town it appears I need to replace my differential, as it is giving me vibrations and sounds/groans of displeasure upon acceleration, up to about ~30-35 MPH, above which they make way for drive train sound-effects unbecoming of a Mercedes.
This is a known/presumed fault so I am not too concerned but what are your experiences with buying cat-in-the-bag replacement differentials...?
Cheers
Been a very long time since I visited these parts - happy to see y'all still around, even with a banner ad for each sub-forum
My trusty old W220 320 CDI (post facelift) has received a reanimation-level servicing last month, as it was in a rather sad state for a while. New air strut, front brakes, shiny new steering rack and indeed a new MB OE power steering pump, bushings on the drive shaft... a whole bunch of TLC. Further gradual rectifications are in the works
Despite it's 20 years it still drives like a dream!However, a significant Freude Am Fahren-damping condition persists... it received two new Delphi ABS sensors on the front wheels as it had been limping in ABS/ESP fault mode for the better part of a year. For good measure, one front wheel bearing was also replaced.
Post-repairs, on ignition, ABS and ESP report no fault, but the moment one starts driving the following happens:
1) Braking more often than not causes the pedal vibration alert, at least a little;
2) Exceeding the speed by, say, 20 MPH will cause the ABS to disengage/show the ABS/ESP error;
and perhaps most confusingly...
3) Above about 18-20MPH the speedo starts to... dance around... up and down... like, when going 60 KM/h it may very wel jump down to 40 KM/h, and anywhere in between. It does not, it appears, ever display a speed higher than the one driven, only dip down to lower ones. Now - one thing that might be of note: When going 25-55 km/h, the digital speedometer (on the central display) joins the needle in its erratic speed reporting... however above about 75-80, it almost never does.
This tells me that:
- the higher the speed, the more frequent the signal;
- above a certain frequency the digital display (which is a bit... "lazy", so to speak) doesn't bother to display the briefly received erroneous speed;
- it would seem the issue is the computer now and then getting the WRONG signal, rather than NO signal;
- therefore - it is a signal error, not a calculation/processing error.
My most competent mechanic has replaced the ABS sensors (and this did eliminate the "at fault from ignition"-condition the car had previously) but is now suggesting it might be the ESP/ABS computer gone bonkers. I trust the man wholeheartedly, but as per above deductions, I have a measure of doubt about this claim. It's not... expensive to "prove" - a computer can be had for 30 quid and for another, what 40? I can have it reprogrammed by some Dude With A STAR-Laptop.
But it just does not seem to make sese the computer would suddenly kick ze proverbial bucket, and the nature of the issue tentatively suggests other possibilities may be at play. Electrical wiring? Corroded contacts? Warped "funny little metal disk with slits for sensor"...?
What sayeth ye, oh online Oracle of Wisdom of all things Mercedes...?
Also, in another part of town it appears I need to replace my differential, as it is giving me vibrations and sounds/groans of displeasure upon acceleration, up to about ~30-35 MPH, above which they make way for drive train sound-effects unbecoming of a Mercedes.
This is a known/presumed fault so I am not too concerned but what are your experiences with buying cat-in-the-bag replacement differentials...?
Cheers
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