[v12-engine] Running on six cylinders

1994 XJ12, starts & idles, but low power, right bank not very hot
and very low exhaust at the rear. Local shop installed a CAT said
the old one was clogged up. No help. Also gas smell. Need help.–
Ron Bundy
Fort Washington, Md, United States
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In reply to a message from Ron Bundy sent Thu 8 Jul 2004:

Hmmm…
any spark to any of the dead(?) bank?
have you got a timing light?–
The original message included these comments:

1994 XJ12, starts & idles, but low power, right bank not very hot


Sixfan 57 Mk1 (x2) Ser 2 XJ6, XR6 turbo + C210 Skyline
Brock’s Creek N/T, Australia
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Ron, it sounds like the “typical” Marelli ignition failure (cap and rotor).
One bank is firing and the other is dumping raw fuel into your CAT. Do not
drive it in this condition as most Jag fires are caused this way. See Kirby
Palm’s “Experience in a Book” for a silicone fix for the rotor to prevent
such failures in the future, when you replace the cap and rotor.

Jim Johnson - NCJOC
'88 XJ-S, V12, Lucas (CEI), TH400 (w/B&M), Dana 2.87
Annapolis, Maryland

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Ron
Not sure if this late model used Marelli but if it did the standard
response is don’t drive it without fixing the distributor or the car
will burn!! And don’t go back to that “local shop”, they don’t have a clue.
Steven

Ron Bundy wrote:

1994 XJ12, starts & idles, but low power, right bank not very hot
and very low exhaust at the rear. Local shop installed a CAT said
the old one was clogged up. No help. Also gas smell. Need help.

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 !

In reply to a message from SJ Hall sent Fri 9 Jul 2004:

Ron,
There’s a good chance the interior your original cat was melted by
the burning of raw fuel inside it. The most common culprits for
one bank cutting out with the Marelli system are the rotor and/or
distributor cap. If you’re lucky, you’ll find one of them
defective – an easy fix. An OEM cap is pretty pricey, but at
least you can intsall it yourself. I think the general belief is
that aftermarket brands do not hold up well to the heat of the
V-12, so you’re better off investing in the real thing. Good luck!–
John - '90 Majestic, '95 XJ-S 6.0 Conv., '86 Volvo 760T
Stamford, CT, United States
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In reply to a message from John-in-CT sent Wed 21 Jul 2004:

I replaced the cap and rotor with new marelli. Still not running
on bank A. Very little exhaust out of right side, strong and hot
on the left side. Starts and idles OK. Is there a check list to
go on that will eliminate coils, wires, ect?
My experience is with XJ6. This 94XJ12 belongs to my neighbor and
had a new cat installed and a new aftermarket cap. The cat was
not connected at the rear I believe it probably blew off from gas
build up. Fuel smell is fairly strong. I pulled the O2 out of the
new cat, it is a bosch, is this factory?
Thanks to the forum for the suggestions on the first posting, hope
to get more. Can the coil wires be swithced, or do they both have
separate timing?–
The original message included these comments:

one bank cutting out with the Marelli system are the rotor and/or
distributor cap. If you’re lucky, you’ll find one of them


Ron Bundy
Fort Washington, Md, United States
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