XJ 6 Series III 4.2 - Cold Start EFI Overfuelling
At the request of several list members, I posting the text of the Jaguar Canada technical service bulletin which outlines the capacitor "fix" for cold start overfuelling problems.
JAGUAR CANADA INC.
TECHNICAL SERVICE BULLETIN REFERENCE B-001 VOL V
MODEL XJ6 SERIES III 4.2
SUBJECT: AIR FLOW METER
It has been established that the cause of some 4.2 Series III engines misfiring and issuing black smoke from the exhaust when the car is accelerated or driven way with the engine in either a cold or part warm state, is due to overfuelling. This is produced by continuous triggering of the acceleration enrichment circuit during the warm up period (Note: There is no acceleration enrichment above 75*C).
The acceleration enrichment circuit can malfunction in this matter due to either poor or dirty connections on the airflow meter plug/socket connection.
Should this problem be reported, dealer should check and ensure that the air flow meter socket connections are clean and have good continuity.
Should dealers find that these actions do not resolve the overfuelling problems, the following Service Fix should be implemented.
A 100 Micro Farad, 25 Volt Electrolytic Capacitor should be soldered across terminals 6 and 8 of the Air Flow Meter harness multiplug ensuring that the negative lead of the capacitor is connected to terminal 6 and the positive lead of the capacitor is connected to terminal 8.
100 Micro Farad 25 Volt Electrolytic Capacitors are readily available from most reputable radio/electronic dealers.
SERVICE FIX PROCEDURE:
[Figure 1 not reproduced - simple drawing of harness multiplug]
Alex notes the following:
Improve your Jag-lovers experience with the Mozilla FireFox Browser!
View the latest posts from our Forums via an RSS Feed!
©Jag-loversTM Ltd / JagWEBTM 1993 - 2019
All rights reserved. Jag-lovers is supported by JagWEBTM
Use of the Jag-lovers logo or trademark name on sites other than Jag-lovers itself in a manner implying endorsement of commercial activities whatsoever is prohibited. Sections of this Web Site may publish members and visitors comments, opinion and photographs/images - Jag-lovers Ltd does not assume or have any responsibility or any liability for members comments or opinions, nor does it claim ownership or copyright of any material that belongs to the original poster including images. The word 'Jaguar' and the leaping cat device, whether used separately or in combination, are registered trademarks and are the property of Jaguar Cars, England. Some images may also be © Jaguar Cars. Mirroring or downloading of this site or the publication of material or any extracts therefrom in original or altered form from these pages onto other sites (including reproduction by any other Jaguar enthusiast sites) without express permission violates Jag-lovers Ltd copyright and is prohibited