Power dip/hesitation briefly after upshift (diesel, auto)
09-20-2023, 12:13 AM
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Power dip/hesitation briefly after upshift (diesel, auto)
For as long as I've had my 2008 525DAT LCI (since late 2016) it has had this thing it does:
On light to moderate load in D, S og even M, after changing up the power stays on briefly, dips for half a second by a third, and comes back on. Under hard acceleration it either doesn't do it or I can't feel it. On rare occasions it doesn't happen at all but I can never replicate the conditions. I've become so tired of it after seven(!) years and want to sort it out.
The car is stock. I've reset the adaptive transmission settings multiple times, and throttle settings. The car is serviced, I recently cleaned the MAF and MAP sensors, have a fresh air filter in and it's had general maintenance over 60k kms of ownership. What I don't know is the gearbox oil level. I do know it was flushed at 120k kms and is soon due for an oil change again. Current mileage 211k kms. All other gearbox behaviour feels correct. I've searched extensively for solutions but nothing so far. Carly has never thrown up any drivetrain or fuelling faults.
(Don't know if it may be related, but it also likes to slip into a false DPF regen mode when air humidity is high. Even from cold. This delays upshifting to +/- 2000 rpm regardless of load, increases cabin engine noise and reduces power. DPF soot and ash levels are normal. I've been told of a sensor on the exhaust side that might fail and cause this?)
On light to moderate load in D, S og even M, after changing up the power stays on briefly, dips for half a second by a third, and comes back on. Under hard acceleration it either doesn't do it or I can't feel it. On rare occasions it doesn't happen at all but I can never replicate the conditions. I've become so tired of it after seven(!) years and want to sort it out.
The car is stock. I've reset the adaptive transmission settings multiple times, and throttle settings. The car is serviced, I recently cleaned the MAF and MAP sensors, have a fresh air filter in and it's had general maintenance over 60k kms of ownership. What I don't know is the gearbox oil level. I do know it was flushed at 120k kms and is soon due for an oil change again. Current mileage 211k kms. All other gearbox behaviour feels correct. I've searched extensively for solutions but nothing so far. Carly has never thrown up any drivetrain or fuelling faults.
(Don't know if it may be related, but it also likes to slip into a false DPF regen mode when air humidity is high. Even from cold. This delays upshifting to +/- 2000 rpm regardless of load, increases cabin engine noise and reduces power. DPF soot and ash levels are normal. I've been told of a sensor on the exhaust side that might fail and cause this?)
Last edited by torketil; 09-20-2023 at 12:17 AM.
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