Interesting observation that the engine was slowing down when it happened. Like what happens when you decel in real life on the road.
You know, one of the things I got explained to me when I bought my 2011 Lincoln MKS, is that Ford has introduced a new fuel saving strategy so that when you lift, it cuts the fuel completely OFF. I can feel it do it in my MKS. This car of mine has the 3.7 which is basically 3/4 of the 5.0... It is called: Aggressive Deceleration Fuel Shut-Off (ADFSO)
Just a thought...as it is leaning down maybe that is what causes the detonation, especially at high rpm. One thing to remember is that gasoline COOLS the combustion chamber as it evaporates. Take it away, and that chamber will run hotter.
Maybe someone ought to look at the code and see if it cuts the fuel to all injectors or staggers them. If it staggers them, then maybe #8 comes up in the sequence too much as having the fuel cut. OR, if it cuts it completely, then maybe someone can re-write this sequence to add a bit of fuel like they did before they implemented this strategy.
I am thinking about what is causing this shit and that could be from:
- Complete starvation of fuel (like when lifting due to this ADFSO)--wonder what the fuel pressure looks like at this moment in time??? Does it kill the signal to the injectors OR to the fuel pump???
- #8 runs hotter due to where it is in the car (airflow around it) and/or how the cooling water flows around it.
- Vapor lock around cylinder #8's fuel rail--again heat related
- Too much timing (but why aren't the rest of the cylinders affected?)
- Low fuel pressure (which I tried to explain wrt the U shaped fuel rail but no one would listen or believe me)
- A combo of 1-5.
BTW, how many of you seen a race car (oval track) toast a piston when they run out of fuel......I think this new fuel strategy could be one of the knobs here...that also lines up with people saying they were just tooling around not hossing it and it blew.
HTH
Mike
PS: As a good Engineer should do: DATA:
http://www.blueovalforums.com/forums/index.php?/topic/27681-aggressive-deceleration-fuel-shut-off/
http://corporate.ford.com/microsites/sustainability-report-2010-11/issues-climate-plan-economy
..and as Foghorn Leghorn would say, "The COOP-DE-GRACE,"
http://www.allfordmustangs.com/forums/2011-mustang-talk/214614-valid-info-new-2011-mustang.html