[ale] Time for this Grey Beard to stir up some stuff

[Steve Litt]

Solomon Peachy via Ale said on Thu, 22 Jul 2021 19:06:31 -0400


>But since you brought this point up, to loop back to the analogy you 
>responded to, modern cars have excruciating detailed self-diagnostics, 
>whereas old pre-electronic cars leave you with an "incompetent
>something went wrong" error (eg "it won't start") that can require
>considerable probing to further diagnose.

Most of the cars I drove were made before 1990, most had carburetors,
and at least three had no semiconductors of any kind. The considerable
probing diagnostics you said were required required were mostly
preventive maintenance:

* Replace the plugs if over 2 years old (gap the new ones)
	- Keep the old plugs for later diagnostics
* Replace the points if over 2 years old
* Replace the spark plug wires if over 2 years old
* Change your oil every 3000 miles
* Change your transmission fluid every 48K miles if automatic
  transmission
* Look at your temperature gauge (not idiot light) every few minutes
	- Necessary on modern cars too

The preceding were usually between dead bang easy and pretty easy on
those simple cars. And the plugs and points were cheap as hell, the
wires were about 2-3 hours pay for a programmer. The preceding being
finished:

* Check for spark, and if none, suspect the coil if you replaced the
  wires, points and plugs.
* Use a timing light to check spark the timing
* Use a fuel pressure gauge to make sure fuel pressure was OK
* If old plugs burnt, richen mixture. If fouled, make leaner
	- Could also be rings or head gasket: Expensive then as now
* If the differential diagnosis points to the carb, have it
  professionally rebuilt

As far as modern "excruciatingly detailed diagnostics", look up all the
root causes possible for an PO420 OBD2 message. Careful you don't
replace a fabulously expensive catalytic converter bank when the root
cause is an upsteam O2 sensor, a downstream o2 sensor, an exhaust leak,
an intake leak, a faulty ECU computer, or faulty wiring.

Once again, I applaud modern cars having better gas mileage and
extremely reduced emissions, and understand that such (necessary)
complexity requires self-diagnostics. But the assertion that modern
cars have "excruciating detailed self-diagnostics" just doesn't pass the
smell test.

And, as I said in a prior post in this thread, although computers are
necessary for proper engine performance, using them to control every
blasted thing on the car is obscenely complex entanglement.

SteveT

Steve Litt 
Spring 2021 featured book: Troubleshooting Techniques of the Successful
Technologist http://www.troubleshooters.com/techniques