I feel that my car is loss power at 4000 rpm, I try to push my accelerator pedal but the car can't pull again, and like the power is not accelerate again.
my car is m40 318i, does is it normally?
thank you
markus
loss power/flat spot? in the 4000 rpm
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markus_74
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Grrrmachine
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Loss of power over 4000rpm on an M40 engine is normally due to a worn camshaft.
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markus_74
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thank you for the info, but it is not the camshaft cause if I change the afm the power will increase at above 4000 but at below the power is not good.Grrrmachine wrote:Loss of power over 4000rpm on an M40 engine is normally due to a worn camshaft.
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Grrrmachine
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Selamat Siang 
AFM's get worn on the carbon track; if you remove the plastic cover (carefully, with a sharp knife) you will see a metal arm moving over an area of carbon, a bit like an old record player. If you're careful, you can bend this arm slightly so that it moves over a new, clean area of carbon. This may repair your AFM and return your power above 4000RPM.
AFM's get worn on the carbon track; if you remove the plastic cover (carefully, with a sharp knife) you will see a metal arm moving over an area of carbon, a bit like an old record player. If you're careful, you can bend this arm slightly so that it moves over a new, clean area of carbon. This may repair your AFM and return your power above 4000RPM.
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Brianmoooore
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Check out the distributor cap and rotor arm before getting involved with anything else.
Don't remove the cover of the AFM until you have tested it and proved it faulty.
Test by connecting a 6 or 9 volt battery across the ends of the pot. track, and monitor the voltage on the rotor as you move the flap slowly open by hand. The voltage should always increase - the slightest 'drop out' or fall in voltage indicates it's faulty.
Don't remove the cover of the AFM until you have tested it and proved it faulty.
Test by connecting a 6 or 9 volt battery across the ends of the pot. track, and monitor the voltage on the rotor as you move the flap slowly open by hand. The voltage should always increase - the slightest 'drop out' or fall in voltage indicates it's faulty.