Assembly requires cookies to securely sign you in. On iPhone or iPad, open Settings → Apps → Safari → Advanced and turn off “Block All Cookies.” Then fully close Safari, reopen it, and reload this page.
Long running issue on cold starts- always sputters on the first crank. After waiting a few seconds, it fires on the second crank every time.
Any ideas? As documented on https://www.m5board.com/threads/cold-start-crank-no-start-immediate-second-crank-starts-right-up.620207/page-2?post_id=7747106#post-7747106
COMMENTS
2
drive_revive_tinker
· Jun 13
Can’t speak to the specific musings of the S85 engine management, but those symptoms do sound just like fuel pressure bleeding down.
Seems like it’s getting up to pressure quickly, but not quickly enough for the expectations of a push-button start system. Im not sure how the M5 handles priming with the push button start, or when prime, cranking and run occur on the plot you shared in that linked thread, but if I’m interpreting correctly, it seems you have 0 fuel pressure and then it quickly jumps up to the starting pressure target. Not sure where the check valve is in that car (guessing integrated into the sending unit) but I’d be looking at that.
If you hold the start button down long enough (the first time, not a second time) will it start? Or does it always require you to let off the button and push a second time to get it to start?
0
0
weapau
· Jun 13
I do let the system prime before starting- one press without the brake pedal. I can hear the fuel pump. As I mentioned in the thread, I did the whole fuel system plus the injector remap at the same time, so I can’t isolate the change.
Out of town for the rest of the week, but I plan to take a day or two off this summer to test a few things, and may have to acquire a smoke machine to check for intake system leaks.
