TD5 90 Revs not dropping on gear change

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tom1979

tom1979

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About a week ago I noticed the revs seems to “cling on” when changing gear. Initially I thought clutch switch however I can see via the Nanocom the switch appears to work. Anyone any other ideas why this might happen ?

cheers
 
tom1979 said:
About a week ago I noticed the revs seems to “cling on” when changing gear. Initially I thought clutch switch however I can see via the Nanocom the switch appears to work. Anyone any other ideas why this might happen ?

cheers
Click to expand...

Hi tom1979
A neighbour of mine had this very same issue on a TD5 he purchased revs not dropping when changing gear. This did not happen all the time mainly in the lower gears after using higher revs to create some inertia when climbing a hill say.
After a lot of searching himself and the use of a Nanocom he was unable to pinpoint the problem. So off to an expert who took it out for a test drive with a diagnostic tool connected was only away 5 min back at the garage he then adjusted the wastegate actuator to make it longer, another test drive again 5 min back at the garage said that should do the job and charged £30:00.
Sure enough the issue was sorted the previous owner had adjusted the actuator just a little too much.
The guy at the garage said he had come across the problem a number of times, also a remap can cause the same issues but not so easily sorted.
Good luck .
 
Tim4x4 said:
Hi tom1979
A neighbour of mine had this very same issue on a TD5 he purchased revs not dropping when changing gear. This did not happen all the time mainly in the lower gears after using higher revs to create some inertia when climbing a hill say.
After a lot of searching himself and the use of a Nanocom he was unable to pinpoint the problem. So off to an expert who took it out for a test drive with a diagnostic tool connected was only away 5 min back at the garage he then adjusted the wastegate actuator to make it longer, another test drive again 5 min back at the garage said that should do the job and charged £30:00.
Sure enough the issue was sorted the previous owner had adjusted the actuator just a little too much.
The guy at the garage said he had come across the problem a number of times, also a remap can cause the same issues but not so easily sorted.
Good luck .
Click to expand...

interesting, so along the lines of boost creep?
 
tom1979 said:
interesting, so along the lines of boost creep?
Click to expand...

tom1979,
Not exactly boost creep, The guy in the garage did give an explanation to my neighbour (neighbour not technical sort of person) and he to me and it went something like this.
A definite over boost creates a fault code that triggers a limp home mode until reset by turning off the ignition a number of issues can trigger the over boost.
If the boost becomes high but not over boosting on a regular basis (the figures of 1.2 bar = over boost 1.1 bar high boost) the ECU has a memory it remembers at these revs the boost pressure is high and try's to protect the engine without going into limp mode and one of the consequences of this is the revs staying high at a gear change. By reducing the amount of boost that can be achieved 1.0 bar or less then the ECU will not try to compensate.
The problem is a bug in the ECU software an unintentional consequence of protecting the engine.
 
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