Re: [xj-s] Re: 4 wire diagnostic connector (XJ-S Digest V2 #205)

[Costantine.Vloutely@learjet.com]

Can anyone tell where I can find the test connector on the 1990 XJ-S???
Looked for it, maybe it does not exist!!!

Thanks for,any leads.

Connie V.






corsaro@brokersys.com on 07/13/98 02:25:30 PM

To:   davidj@ecentral.com
cc:   xj-s@jag-lovers.org (bcc: Costantine Vloutely/BFTC/Bombardier)
Subject:  [xj-s] Re: 4 wire diagnostic connector (XJ-S Digest V2 #205)




David Johnson wrote:
>
...
>
> I found the mixture was VERY lean when in open loop (below 1% CO). The
> mixture was OK when in closed loop (about 1 to 2% CO). The voltage in
> closed loop was about 2.5V to 3.4V in closed loop, and 1.85V in open
loop.
> This indicates a lower voltage gives a richer mixture. I guess this is
why
> jag put the computer in OPEN loop when in park. There are LESS emissions.
> This suggests to me that you should NOT disconnect the jumper for the
> emissions test. Any comments.
>
David,
in open loop the 02 circuit is disconnected from the rest of the circuits.
The 1.85 volts you read was the 02 circuit just 'talking to itself', it
has no effect on mixture. However, 1.85 still seems low, I'll check it
out next time I work on an ecu .
In theory (on the xjs) the open loop mixture should be close to the
center of the closed loop swings. If the car is leaner in open loop idle
you can adjust the idle CO setting. If it's leaner in open loop at
2500rpm (where the idle CO adjustment has no effect), then your fuel
pressure might be a bit low or something else might be making your
car run a bit lean... ask Kirby or group for input on that.
Don't know if I should include this.. might offend the purists :), but
for the sake of completeness here 'this' is.
If you need to increase the fuel pressure just ONE OR TWO TENTHS of a bar
you can try this on the pressure regulator (driver's side one (US) if you
have two):
Put a small pulley wrench around the top of the regulator with a socket
over the vacuum port (the legs of the wrench grabbing the bottom of
the ridge around the regulator). Turn the wrench screw down onto the
top of the socket. Turn 1/4 to 1/2 more turns then remove wrench,
reconnect vacuum hose and check pressure/feedback voltage. Repeat
procedure until the fuel pressure/feedback voltage is where desired.
Again, do this only after you have checked out all other possibilities
for lean condition.
 Walter
PS Will borrow Kirby's quote on this one:
   If anything is to be accomplished...

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