Engine Diagnostics.

[John Dammeyer]

Hi All,

I've noticed a fair number of different postings regarding FI controllers from
stock automotive units to the roll-your-own type.  I'd like to tap this rather
wide body of experience and begin a dialog on engine diagnostics.

In particular:
a)  the engine refuses to start
  i) What sort of diagnostics do the 'stock' units provide?
  ii) What sort of diagnostics do the homebuilt or after market units provide.

b) engine starts and runs for 30 seconds (or 5 seconds or 1 minute...)
  i)  As above.
  ii) As above.

c) engine runs, warms up properly and then suddenly dies at cruise speed (say
2500 to 3500 RPM)
  i) as above.
  ii) as above

d) engine runs but dies at full power or refuses to reach full power.
  i) as above
  ii) as above

d) engine runs but enters 'limp home mode'
  i) as above
  ii) as above
  iii) What constitutes limp home mode for a FI implementation.

e) engine starts and runs but then suddenly develops a 'wicked' idle.  Perhaps
lots of hesitation to move from idle.

Obviously,  MAP verse MAF systems will create different diagnostics but what I'm
looking for is information that will help a mechanic diagnose the problem
without needing a complete laptop PC.  Some systems use a lamp and create a
flashing sequence with 'fault codes'.  What sort of codes would be useful?

I am assuming that some basic engine troubleshooting techniques are available
like: is there fuel; is the battery above the minimum specified voltage? etc.

Assuming the engine controller works properly,  what sort of information could
be provided to help someone diagnose a damaged sensor etc.

Thanks,

John Dammeyer