Posted by George Georgiou on March 6, 2010, 3:18 am
Year of Manufacture *: 2001 Engine Code or CC *: M54 2.2
Non-start. Car driven home one evening all OK. Next morning refused to start. On a couple of earlier occassions car would start, idle and cut out , but eventually restart without problem.
Launch Code scan DME MS43 M54 code 227 & 228 Fuel trim bank 1 & 2 permissable range exceeded; 47 Torque limitation , safety concept level 1 ,8 signal air mass flow sensor.
Codes cleared , no codes during testing.
There was no sign of starting even with prolonged cranking and easy start on inlet.One or two slight coffs but generally cranking with no sign of life. Removed MAF connector, no difference.
Good crank sensor and cam sensors x2 on pico during cranking. All injectors 15 ohms approx each , Ignition pulses present with 9ms + on times. Good shape to ignition pulses.Ignition pulses suggests lack of fuel. Checked flow and pressure (50PSI, 2.5 litres KOEO) at pump and also on fuel rail, pressure same on rail and free flow fuel through coda pushing more than 3 litres/min.
Customer later on replaced combined fuel filter with regulator unit . Made no difference.
Good Spark present on all coils but still need to measure strength.Some signs that coil packs are cooked , but no faults logged by ECU to indicate misfires.
Only after removing/drying/cleaning wet plugs and putting back did I manage to get engine to start and 'run' weakly but only whilst cranking, but after a few goes it did not run at all again, suspect plugs wet again.
Smoke test revealed tiny hole in rubber banjo on inlet hose to inlet manifold and leaking blank off pipe rubber. Repair did not fix problem. No other smoke leaks visible to suggest cracked inlet manifold or breather pipe faults.
Compression tests need to be repeated may be affected by bore wash , some were around 150PSI , others 125 PSI and only one was low at aroung 50 PSI. One cylinder down out of 6 would surely not prevent it at least starting?
Immobiliser on rear view mirror signals correctly with lock/unlock of vehicle and since we get sparks and injection this must rule out the immob.
I have good sparks, fuel pressure/flow, injector pulses, cam and crank signals , and no manifold air leaks , also reasonable compressions, why is this engine not starting or even giving an indication it wants to start? What have I missed?
Sorry for the ramble but I have spent as you may have guessed a fair bit of time on this one and it could be my first no result of 2010.
If you have one cylinder down this should not produce a non-start situation. If you have a good spark, compression and fuel then that car should start. Also I have found that Easy start will start a dead horse . As Dave says it is likely you have a blocked exhaust.
Regards
Pete M
Fixed # - For now!
Posted by George Georgiou on March 6, 2010, 11:18 pm, in reply to "Re: BMW E39 520i 6 CYL M54 2001- Non Start" Message modified by board administrator March 7, 2010, 12:44 pm
Thanks for replies , yes it could be blocked exhaust or bad fuel but read on....
went back for more on this . re-checked fuel pump relay OK. Still cranking no start after several attempts.
Decided to put pico on coil packs to look at ignition in detail. Pulled back rubber boots and looked at first coil pack , the pulses were random and of different voltage peaks showing no ringing . But after a few more cranks the engine started . It was also noted that we had a smell of petrol just before it started. There was no smell of petrol during the previous extended cranking tests.
Engine revved freely, no sign of any misfire , fast idle soon settled to slow idle as it started to warm up as normal. Also stopped and started engine soon after it first started with no problem.
Looking at the scope , all 6 coil packs were showing clamped output at about 110volt peaks with seven 'pre-spark' ignitions before switching off but with no coil ring on any coil pack. This suggested all 6 coil packs were faulty. Not very likely!!!
But gradually I guess as engine warmed up the coil pack ringing appeared on all 6 coil packs and the output peaks reached 400 volt peaks , again clamped all to to the same peak, very strange that all seemed to be exactly the same.
The seven pre-spark peaks reverted to one single coil pulse as one would normally expect to see but only when the rev were raised slightly. Dropping back to idle always produced the seven spark pulse. I have seen multiple spark pulses before on BMW .I guess this is how BMW fire their coil packs to ensure complete combustion at idle i.e. multiple sparking events, reverting to one conventional spark as revs pick up.
I cannot decide what caused the car to start . However it might have been the change of fuel filter with its combined regulator but I am thinking its something to do with a duff ECU/Coil drivers.
I removed and inspected the ECU and it was in perfect condition inside , no signs of power transistors damaged in any way. Put back ECU and again car started and ran perfectly.
Ran a vacuum check. Vacuum was perfect and steady and doing a WOT check showed vacuum response perfect, so no valve problems.
Customer reported the car never drove better after a short test drive with much better response to acceleration. I put this down to removing air leaks after the MAF spotted on smoke test or possibly the fuel filter swop or cleaning of sparks.
Recommended fitting of a new set of sparks. Re-checked fault codes and cleared DME. Advised customer to run car and call me if problem re-appears . It starts and run extremely well so nothing more I can do for now.
on March 6, 2010, 9:22 am, in reply to "
. As Dave says it is likely you have a blocked exhaust.