The crank angle sensor is a single point of failure. There is only one,
so it's not redundant even if you have two controllers. However from my
experience driving RX-7s (70 miles round trip to work for the last 10
years) I've never seen one fail. Haven't seen an ECU fail either.
Occassionally one of my cars wouldn't start, I would unplug and then
reseat the crank angle sensor connector and it would then start. I've
only seen this phenomenon on one car. Probably just needed some contact
cleaner.
Generally I think any problem with the crank angle sensor would mean
the engine wouldn't run at all.
Might be good to have one controller running on the stock crank angle
sensor and a second running from an independent sensor on the e-shaft
front pulley.
You can't have redundancy everywhere. I have one cranks sensor and one
ecu and my engine has never quit running in 600 hours. If you really
want redundancy build a plane like a twin-engine Defiant, that can
truly fly on one engine.
Perry
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I understand that it's totally natural to feel defensive in this
situation. I know you may find this hard to believe, but the goal of
the post is to help others reduce risk. It's not a personal attack.
There's no rotary reference in it anywhere. As far as the readers know
it's a piston engine. But I hope there's at least one person on this
list that sees value of looking at the other causes.
The essence of the post is accurate. Doesn't matter if you are
near home base or not. Ignition failure is very high risk item. An ECU
that was better at self diagnoses would have greatly reduced your risk.
On your car, it would be recognized immediately. Ecu would say "Hey, my
cam sensor just went thru it's normal 50 pulses per revolution with the
normal 5 and 8 ms. gaps. But I didn't get the normal 20 pulses and
signal gaps from the crank sensor. Turn on warning lamp and crank code.
Use cam sensor for timing info." You don't see value in discussing
stuff like this? If you guys just used toothed wheel with pulse gaps,
then the ECU could easily self diagnose.
You know what was cool on the other list? Guys came back with
"confessions" of how this parallels a problem they encountered. 2 guys
said, "yeah, I had partial failure, thought it was x, took off only to
find it was y". Then other guys described changes they made to system
that totally eliminated the risk. Some really creative stuff. Then we
discussed just how risky crank sensor really is...we see one ever 1 1/2
to 2 years. Etc. Etc. Very positive experience that may save someone's
life. That's the goal.
Hi Tim,
Isn't it wonderful how stories get twisted around as they fly from list
to list. Obviously this particular twisted story relates to my recent
experience, so let's dilute the fun a little by adding some truth.
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