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Thanks Perry!
That was what I was looking for.
I didn't mention names because I didn't want things
to get personal, but I guess everything is out in the open now...
Every conversion I have seen so far has some
non-redundant items. One example on the Subaru side, I have seen
backup ignition controllers, but all the engines I have seen only have one
sparkplug per cylinder. Is redundancy needed there? I'm not
certain. Normally I would say no. But I just had a plug failure
strand me while riding my motorcycle. (First time ever for me... and no,
it's not a V-Twin) So now it raises a red flag... there have been
other red flags, but this was just the first thing to come to mind.
I do know that a 91 Porsche 911 engine had dual
plugs, dual distributor, dual coils. Maybe replace the distributors with
electronic ignition. Parts would be pricey though... typing out
loud again.
So now I have confirmation that a crank angle
sensor failure will shut down an engine. But it also appears that a crank
angle sensor failure is extremely rare (difficult to quantify, but there seems
to be a general consensus on this). Something else that would be
interesting to find out is if failure usually occurs during operation (stress),
or during idle time (corrosion, etc.). If the primary failure point is
before startup, then the risk is relatively benign (not happening in the
air).
I hope everyone here (and other mailing lists for
that matter) continue to report their successes and failures. I have been
following (and cheering on! :-) ) John Slade for a while now. I just hope
you don't give up on the A/C system John, now that you have moved out of
the tropics and north of the Mason-Dixon line!
Back to lurking!
-TP
----- Original Message -----
Sent: Saturday, June 10, 2006 11:49
AM
Subject: [FlyRotary] Re: Ignition
Failure
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
-----------------
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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