gyroskalamari
Member Since: 13 Dec 2021
Location: Munich
Posts: 1
  
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| Extreme idle revs after cold start |
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Hi all,
I have had a (new) problem with my LR3 V8 for a few weeks.
The idle speed has always risen to well over 1000 rpm after starting. For some time now, however, this value has been at 3000 rpm, sometimes even higher. Otherwise, the Disco behaves normally, and the IIDTool cannot detect any errors in the engine control. Hearing the cold engine revving up at this speed gives an unhealthy feeling. When it is warm, the effect no longer occurs.
The friendly guy read out all the relevant sensors without finding anything, updated the ECU, didn't know what to do next and, feeling guilty, wrote me a bill for two hours of work.
The following measures have been carried out so far:
- all errors deleted with the IIDTool, complete reset of the vehicle, PCM engine adaptation values deleted
- air mass meter unmounted, cold start with unplugged air mass meter --> same effect
- cold start with open air filter housing --> same effect
- throttle valve cleaned --> same effect
- cold start with unplugged throttle valve prevents the effect, but leads to an error in the engine control (yellow engine LED on)
- EGR control unplugged --> same effect
- EGR on the intake manifold closed with duct tape --> same effect
- starter battery freshly charged and/or connected to consumer battery via DBS --> same effect
- vacuum hoses towards valve chamber and purge valve (activated carbon storage) disconnected --> speed increases rather than increasing
- accelerator pedal replaced --> same effect
- crankcase regulator valve replaced --> same effect
I looked at the TARGET/ACTUAL values of the throttle valve in the IIDTool “Live Values”. Although they are at different levels on the absolute scale, they behave the same in relative terms.
According to the “Target Idle RPM” value, the engine control unit does indeed command a speed of around 1800 rpm after a cold start, although the actual speed is significantly higher than this.
I'm slowly running out of ideas as to where else to look. Has anyone had a similar experience with the V8 or knows someone who knows someone...
I'm grateful for any advice!
Best regards, Eckard
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 20th May 2024 11:01 am |
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