[v12-engine] 85 xj12 update enmissions

I failed CO, and HC…
Perhaps fuel pressure.
After the debate a couple of weeks ago of where to check the pressure , I
tried two spots.
#1-- Teed in just after fuel pump in trunk.
Results---- steady 45psi…
#2 Cut fuel line between first regulator and rail and installed tee.
Results— steady 30 to 31 psi.
Pulling the vacuum line on A bank reg caused rapid fluctuations of about 3
or 4 lbs–
Pulling vac line on B bank did not.
The A bank reg definitely seems to smooth out the pressure.
Idle stumble---- Finally decided that A bank was mostly the culprit…
Thought that if I pulled one plug wire at a time and listened to exhaust
that perhaps I could isolate the culprit cylinder.
Voila, #4---- Pulled out the wire and pulled back the plug boot and found
the end very rusty and corroded.
Refabbed a wire from an old tempo set laying around , and the stumble
definitely diminished considerably.
I installed three wire O2 sensors, and noticed that it hunts about 50 to
100 rpm’s in closed loop.
A couple of days ago I took it to a place to check emissions that was
different then the first place. (The first place was closed on that day and
I didn’t wish to wait.)
The second place told me afterward that they couldn’t put it on their dyno
so they had done what they considered a gentler test and did a fast idle
test. (2500 rpm)
Had I read the BOOK closer I would have realized that in fast idle, the new
O2 sensors I had just installed were not doing anything.
Tomorrow I’m sending the car back to the first place where he did a dyno
test at 40 K/mh.
I hope that the new O2 sensors plus the repaired plug wire do the trick.
I was going to pull the ECU, and adjust it per the BOOK, but I think that
only effects idle, and it seems to be held on with pop-rivets.
One last thing I noticed---- When using my nose the A bank is moderately
stinky, while the B bank is relatively clean.
The timing is relativelly close, but I know I stretched the springs when I
did the centrifugal advance overhaul. Shrinking them is tough but I gave it
my best shot. The fat spring never did end up doing anything that I could
Ain’t these cars fun?

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I don’t know if this will be any help at all, but on my (carbureted) V-12
the cause of a very stinky bank was a vacuum leak on the other bank. I
replaced the hose and the emissions came right down.

Mike Eck
New Jersey, USA
'51 XK120 OTS
'62 3.8 MK2 MOD
'72 SIII E-Type 2+2----- Original Message -----
From: “Russell Barnes” barnes86@rogers.com

I failed CO, and HC…

One last thing I noticed---- When using my nose the A bank is moderately
stinky, while the B bank is relatively clean.

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