K12 2006 1.2 sport wont rev over 3000 while driving

Hi everyone im having a problem with my micra 1.2 sport. The car has no fault codes showing on the ecu (checked with snapon diagnostics) and sound fine ticking over and will rev fully while standing (not in gear). When i drive it i can hit 4000 revs in first then after hovers around 3000 revs in all other gears. I have tried replacing the throttle body, cam sensor and accelerator pedal and bypassed the cat to no avail. can any one shed some light??

Thanks in advance

Also forgot to add the clutch is fine with no slipping
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tried new throttle body, cam sensor crank sensor. tried searching limp nothing the same only one thread with no answer. when i got the car it had the engine management light on which was the cat.. cleared that my wifeˊs been running around in it with no further faults showing and clutch good for another 15k even tried a spare good engine off my mate and still the same.
K12 Loss of Power/Rev Limiting/Holding Back

  1. Check the charging voltage throughout the rev range. Should be 14 volts approx, with load headlamps /rear screen heater on and/or off. Note that many vehicles built after 2004 have the regulator built into the ECU module and not the alternator.
  2. If out of normal voltage range than disconnect alternator and test drive a short distance to see if any improvement in rev range is obtained. If no improvement, reconnect alternator and move to test 3.
  3. Isolate unplug the front and tail lamp clusters one at a time and test drive, turn the main lights on and off looking for any improvement change due to each lamp cluster being disconnect isolated.
  4. If no improvement found, then isolate each front and rear lamp cluster via the fuses and repeat test procedure item 3. above.
With reference to and read the whole threads to the end;

With reference to; http://www.micra.org.uk/threads/very-slow-acceleration-k12.59307/


ECU limits engine power automatically if it has input indication that any brakes are on. This may be due to an electrical fault such as wet/condensation in wiring and electrical can-bus assemblies anywhere, as well as ABS brakes and electronic stability control circuits. Common sources are loose /corroded/waterlogged rear tail lamp cluster PCB can bus assemblies, fog lamps, number plate lamps, & indicators. Also firewall bulkhead rainwater leaks, possibly from incorrectly installed pollen filters, leaking down onto ECU modules located under the dashboard area.

Cars stuck in limp mode-check reverse & brake lights are working-check cruise control as it is linked to brake light/reverse switches and fuses.
Reference: http://www.efispares.com.au/tradetips.aspx

All of the above test sequence, to reveal possible sources of on load engine control ECU errors, can be carried out by a competent DIY person with minimal equipment and at little or no cost, just time, perseverance & motivation to save money.

You appear to have tried all the obvious related items to engine control and rev limiting, however the ECU is connected to many circuits, both directly and indirectly via can-bus data coms, and a fault in any one or combination of them anywhere on the vehicle can interfere with normal ECU operation and thus engine control performance.

Let us know how this control ECU enigma pans out?
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Thank you for all your replies.... especially to plmval.. the problem was as plmval suggested a fault in the wiring to the o/s rear cluster. The earth was non existing. cleared that problem now she goes like a dream.Thanks!!!