entscheidend 0 Report post Posted July 29, 2009 Ok - Im running out of ideas here.. Symptom is - shaky / vibrating idle - when sitting in the drivers seat (with AC off) the seats shakes With AC on - its comes and goes every 1 second = the one above is constant. What I have done: Air filter Spark Plugs Oil filter Oil change PCV valve Intake gaskets / oil separator etc Brake fluid New MAF - Bosch Transmission flush - torque convertor checked all ok What the hell is it??? I have had the car scanned again - no faults ( I was guessing O2 sensors) Could it be the engine / tranny mounts??? These havnt been replaced and after 120k km it could be the issue?? Anyone? Quote Share this post Link to post Share on other sites
BM WORLD 1286 Report post Posted July 29, 2009 faulty spark plug coil?? Quote Share this post Link to post Share on other sites
kiwi535 538 Report post Posted July 29, 2009 faulty spark plug coil??wouldnt that show up as a misfire on a diagnostic scan? Quote Share this post Link to post Share on other sites
[email protected] 0 Report post Posted July 29, 2009 Engine mounts man. Quote Share this post Link to post Share on other sites
jochen 4 Report post Posted July 29, 2009 (edited) Ok - Im running out of ideas here.. Symptom is - shaky / vibrating idle - when sitting in the drivers seat (with AC off) the seats shakes With AC on - its comes and goes every 1 second = the one above is constant. I had similar symptons with ocassional "lurch" and shakes with my E39 540i, and only under idle. First I cleaned the ICV idle control valve - it was all gummed up and sticky, not working at all. Use carb cleaner, really easy to clean. Good to fix that issue but it wasn't the cause of the "shudder" and shake. you know the ICV needs cleaning if the idle speed drops when the motor goes under load: eg, when shifting from P to D, or switching on the AC. If the idle speed drops and takes long to recover, or if the engine stalls, the ICV needs cleaning. A good ICV reacts instantly and the motor will never stall or drop in RPM when the idle load increases. Anyway, back to the shudder / lurch. On my car the shudder was caused by one of the eight ignition coils failling at idle. And only at idle. At revs of >1000rpm there were no misfires. No error codes were ever recorded. We finally diagnosed the problem by running the smooth-running test in the BMW DIS to observe the O2 values in real time. We saw a blip on one cylinder when it misfired. Swapped coil with another cylinder an the blip moved to the other cylinder. Fitted a new coil, and the engine ran perfectly afterwards. PS: don't skimp with 2nd hand coils, you never know when they will fail. Remember: the coil operates at very high temperatures (the motor operates at 105 degrees C) so old coils have been heat stressed a lot.... and may fail... And failling ign coils is a common problem, esp on older cars. Edited July 29, 2009 by jochen Quote Share this post Link to post Share on other sites
entscheidend 0 Report post Posted July 30, 2009 Thanks Jochen - I believe you could be right. When it has been scanned for faults - faulty coils are not picked up I presume? Glen - do you have something to test my coils at low RPM? When I drive the car doing 50km/hour the car runs smoothly? But idle if you can remember back in April when I brought her in idle is shockingly shaky. Can I get my volt meter and test the ohms somehow? I will check the coils first then focus on the mounts. I have to find it eventually... Quote Share this post Link to post Share on other sites
entscheidend 0 Report post Posted August 3, 2009 Anyone - who can test my coils as Jochen has pointed out above? Quote Share this post Link to post Share on other sites
*Glenn* 855 Report post Posted August 3, 2009 Anyone - who can test my coils as Jochen has pointed out above? Last time you bought it over, I spent about 10 minutes looking at it. If you want it diagnosed properly you will need to book it in and leave it with us. Quote Share this post Link to post Share on other sites
jochen 4 Report post Posted August 11, 2009 Anyone - who can test my coils as Jochen has pointed out above? You need the BMW diagnostic software to do some smooth running tests. Took around an hour or so on my car - so you need to leave the car with a BMW guy. Like Glenn. Quote Share this post Link to post Share on other sites
