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Need Help! 09 M8 won't start.

B
Jan 1, 2012
2
0
1
Fairbanks, AK
I just did a top end rebuild on my '09 M8 HCR, jugs & pistons. Everything went smooth and it fired up on the third pull.
There was an "ECU 21" error code when it started so I shut it off after about 10 seconds of running. Found out the code was for a knock sensor failure but now it won't start, just pulls over like the key is off, (except the gauge glows red a little when I pull).
Any Ideas???
 
B
Jan 1, 2012
2
0
1
Fairbanks, AK
Update:
The headlight and gauge glow when it's roped over, plugs have spark, and there is pressure at the fuel rail. I'm pretty much out of ideas at this point.
Could it be a computer issue? EFI not letting fuel in?
 
A

alexhack

Well-known member
Nov 8, 2008
471
53
28
Red Deer, Alberta
I would check the knock sensor since you had that code. Not too sure how to check the knock sensor itself but check all connections are clean, dry and fully together. One might of rattled apart or got missed during the rebuild. Just an idea. Good luck tho.
 

WyoBoy1000

Well-known member
Lifetime Membership
Nov 27, 2007
11,213
3,928
113
Red Lodge MT to North, CO
Take a spark plug out and dump a pop bottle cap of fuel in the cylinder then try and start it. You shouldn't have got that code off idle, might want to look at the pistons.
 
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