Question about 2000 BMW 3 Series
When you say coming up air flow meter what is the code (P0100?). Check that the MAF is clean. Do not touch it but merely spray it with (residue free) electrical cleaner and allow to air dry. Check the MAF socket and pins at the connection are clean. Make sure the MAF connector wiring back to the ECU is in no way broken or abraded Make sure that there is no air leak after the MAF sensor. check every joint entering the air ducting prior to the throttle. I recently had a case where the jubilee clip holding the air duct to the throttle had been fitted too tightly and had split the duct rim along the bottom. It was only possible to see it when the duct union was disconnected. Now check the interior of the throttle body. Clean it thoroughly and rotate the throttle plate with your fingers and make sure it is clean behind. Check every vacuum line connecting with the inlet manifold plenum for leaks. One quick way is to remove each in turn and stopper off the now open inlet connection with you finger. Have the car at idle and disconnect the fuel pressure regulator vacuum line. If the FPR is OK the engine should for a second or two increase in speed and then return to a lumpy idle - this shows that the release of vacuum on the FPR diaphragm allowed a short burst of increased fuel pressure that then resulted in a shortened injection cycle when the Oxygen sensors detected the rich mixture in the exhaust. Now check the injector sockets and the union of the inlet manifold with the engine. A quick way is to spray electrical cleaner in suspect areas and monitor engine response in the next couple of seconds. If the engine momentarily speeds up then the cleaner was sucked into the mix via the point of the leak. Assuming everything has checked out so far let us look at electrics, coils first . If memeory serves the 318 has 2 twin coils so that plugs 1 and 4 share a coil and plugs 2 and 3 share the other. Remove spark plugs and check and compare spark quality on each. Replace plugs and remove leads 1 and 4 from the shared coil. Turn engine over and monitor the spark from the coil terminals. If spark emanates from both terminals then the crank sensor is likely to be OK. Remove the cam sensor socket connector it should be clean and free of oil on the inside. Remove the sensor and check it carefully for signs of cracking or swelling. Cam sensors can fail eventually due to the thermal cycling of the engine. Just rereading your explanation I also wonder about the idle air control motor/valve, that and the throttle position sensor. Worth looking at if the above fails to resolve things.
Posted on Sep 12, 2010
Check the pipes from throttle body/carb, same happened to mine my pipe had a slight tear in it - could barely notice, taped it up and it was fine but recommend replacing it.
Posted on Mar 25, 2011
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Posted on Jan 02, 2017
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