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

[Alex Carver]

My, the strange coincidence of this thread showing up today in my inbox
when I'm scheduling my fourth service visit for a brand new 2020 Chevy
because one or more computers seems to have some kind of issue that no
one can track down. My old 1985 Dodge sits in the garage only because
the head gasket and transaxle gasket started leaking at the same time
and I couldn't afford to repair both so I got a "new" used Chevy with
only 2.2k miles (dealer loaner car).  It's been in the shop more times
since I've had it than my old car did in 2020.  The old one has OBD 1
(not OBD 2) and throttle-body injection but OBD 1 was actually pretty
specific unlike OBD 2 and I still could figure out the problems even if
I didn't have the right tools or equipment to fix them. Saved a lot of
time at the mechanic when I could just drive up and say "Hey Jack, I
think X is broken".  I can't quite do as well with the new car, I can
only give them whatever info the dashboard computer will show me.

On 2021-07-23 13:45, Steve Litt via Ale wrote:
> 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
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