Post by fmiles on Nov 1, 2018 13:51:00 GMT
hello all
This thread will hopefully serve to help others with the same issue I am experiencing.
The Issue
Around town, gear changes are no problem, car behaves normally.
On motorway runs, the problem manifests, occasionally, by refusing to change up to 5th from 4th, or 6th from 5th, despite near redlining.
More recently, its started downshifting when it shouldn't
I have to take over and use manual selection instead.
The Diagnosis
I talked to several mechanics around here; "Duff Mechatronics Unit" was mentioned several times. Not an option, considering the £1000+ bills...
Got the rear discs looked at; apparently, sometimes its the disc assembly that's at fault screwing with the speed reporting. Everything was fine.
I booked it into VW for a £60 half hour diagnosis. They took it up and down the motorway, logging wheel speeds, but didn't manage to reproduce the issue.
So, numerous blank faces, and general silly comments later, I decided to DIY.
Ordered an OBDEleven
Initially, I though I wasted my money. I just couldn't get the Brakes module to work. It sat there for ages, 'Loading Data'. I had to try for several hours, until finally, on one attempt having gone through lots of other working modules, it decided to work. I quickly set it up and went for a drive.
Do you see the problem?!! I have eliminated the front sensors from the results, as they were all within tolerance.
New Speed sensor on order, I hope it fixes the issue! (Or its dodgy wiring, which is a PITA in its own right)
===EDIT (After remedial work) ===
So, after taking a closer look, the rear pickup disc(s) were in a terrible state. Discs, as both were in need of replacing. Co-incidentally, both pickup sensors, for some reason, had surface grinding, and on the left rear, was ground down quite badly.
Its not surprising: My car has done almost 180,000 Miles...
Replaced these, went for a drive. MUCH better. I need to soak test on a long run, but there was no immediate evidence of erratic gear changes.
So, to summarise, although I have not completely signed this off as 'fixed' as there is still further soak testing to undertake, buying an OBDEleven has saved a mountain of pain (I could have taken the advice of a few and gone the new mechatronics unit direction), and saved quite a bit on cost.
This thread will hopefully serve to help others with the same issue I am experiencing.
The Issue
Around town, gear changes are no problem, car behaves normally.
On motorway runs, the problem manifests, occasionally, by refusing to change up to 5th from 4th, or 6th from 5th, despite near redlining.
More recently, its started downshifting when it shouldn't
I have to take over and use manual selection instead.
The Diagnosis
I talked to several mechanics around here; "Duff Mechatronics Unit" was mentioned several times. Not an option, considering the £1000+ bills...
Got the rear discs looked at; apparently, sometimes its the disc assembly that's at fault screwing with the speed reporting. Everything was fine.
I booked it into VW for a £60 half hour diagnosis. They took it up and down the motorway, logging wheel speeds, but didn't manage to reproduce the issue.
So, numerous blank faces, and general silly comments later, I decided to DIY.
Ordered an OBDEleven
Initially, I though I wasted my money. I just couldn't get the Brakes module to work. It sat there for ages, 'Loading Data'. I had to try for several hours, until finally, on one attempt having gone through lots of other working modules, it decided to work. I quickly set it up and went for a drive.
Do you see the problem?!! I have eliminated the front sensors from the results, as they were all within tolerance.
New Speed sensor on order, I hope it fixes the issue! (Or its dodgy wiring, which is a PITA in its own right)
===EDIT (After remedial work) ===
So, after taking a closer look, the rear pickup disc(s) were in a terrible state. Discs, as both were in need of replacing. Co-incidentally, both pickup sensors, for some reason, had surface grinding, and on the left rear, was ground down quite badly.
Its not surprising: My car has done almost 180,000 Miles...
Replaced these, went for a drive. MUCH better. I need to soak test on a long run, but there was no immediate evidence of erratic gear changes.
So, to summarise, although I have not completely signed this off as 'fixed' as there is still further soak testing to undertake, buying an OBDEleven has saved a mountain of pain (I could have taken the advice of a few and gone the new mechatronics unit direction), and saved quite a bit on cost.
