In reply to a message from sbobev sent Sat 13 Aug 2016:
‘‘Also, if I understand correctly, at WOT, i.e., after the
second fuel pump comes online (above 2850 rpm), the O2
sensors feedback is inhibited. The 36CU does the fueling
based on MAP and CTS alone.’’
this is not the case as some states at the time required a
wot pass with the sensors in the tail pipes and federal
emissions had standards that the car had to adhere to
throughout it’s range of operation so the engineers wouldn’t
have written code that allowed an 11 to 1 ratio to happen
unless a default condition existed to activate an
alternative operational condition to keep holes in the
pistons from forming.
there is apparently such a condition happening at the
present time. as I have written recently there are some
sensors that although apparently have no interconnective
relationship with others if they fail or send inconsistent
data back to the ecu will cause problems elsewhere in the
system.there is probably a serial data loss(inconsistent or
missing) somewhere that the main chip is unable to process.
as a primary step…and mind you,we are still sorting out
the quirks of the system even though new adapted code has
been written, check the wiring between the sensors and
header connections(pin to pin). yes…there a lot of them
but patience,time and an ohm meter with clips are the only
tools that are required for that first thorough diagnostic
step.the wiring used on these cars is of small gauge and
termination although better than it was in previous
incarnations still leaves a bit to be desired.
once this is completed and all is well(hopefully) only then
should one look into faults with the control heads.
again…things like faulty components(as was the case with
nigels ecu)or weakened solder joints or even tin
whiskers(temp and moisture cycling problems being the cause
of these) can and do happen given the age of these units.
what people all too often forget is that electronic
components weren’t designed to last forever nor were they
expected to.failures will happen and often do in quite
unexpected ways.
take an older automatic trans vs a computer controlled
trans for an example.
older auto trannys used a kickdown linkage of various and
sundry sorts and a vacuum modulator to sense what the engine
and driver wanted from it and responded in kind.
look at what is required to operate a computer controlled
trans.a control head that talks to other sensors and control
heads located throughout a car/ wiring/relays/connectors.
the order of complexity has magnified and the benefits of
this are negligible at best unless you are after keeping an
engine within a narrow range of operation
because of some mandate by a governing body that required an
easy out for the manufacturer but that’s all about politics
and the epa here in the states.
much more complicated…much more to go wrong.
wire by wire through the connector ends first and then it
will be time to look elsewhere.long leads on the ohm meter
await to start to solve the problem 
=dok=–
thewytchdoktor=v12 fun!/94 xjs 6 litre/ s=k.log w
Winchester Virginia, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !