Quote:
Originally Posted by waybar17
Hello
I've just bought my first M3 V8, which runs very well
However, on cold start, until the revs drop, it has a ticking sound, mainly from underneath or back of engine. The ticking stops about 5 seconds before the revs drop from 1,000rpm to 750rpm. It does not tick at any other point, and not in the 1600-2000 'dreaded bearing rev range'
It's done 52k mile, had the actuators done, and on the original bearings
I've taken it to a dealer who said it was normal and just the hydraulic valves filling with oil, which I don't believe, because the ticking continues until the cold start high revs drop
Any ideas whether this is an issue or normal and if anyone has had the same issue and resolved it
Its filled with TWS 10w60 oil less than 1,000 miles ago
Here's a Youtube link to a short video, demonstrating the ticking when at 1k rpm and then at 750rpm
thanks |
That's completely normal. The engine runs through it's startup routine to try and heat the cats and O2s up the fastest. This is done in combination of timing, injection, VANOS, and SAI strategy. What you are hearing is just an artifact of that through the exhaust.
You can verify this on a cold engine start with
data. And if you are able to graph it--that'd be pretty neat.
You'll also notice that if you idle for too long, the DME will actually raise the idle from 550 rpms to like 700ish. I bet this is when the cats start to cool down and/or the O2 readings It's kinda interesting to me.
I'm trying to search TIS on this...didn't find too specific of information, but there is a target "Diagnosis value" of the O2 sensors the DME targets.