1990 Jaguar XJ12
Thread Starter
|
Junior Member
Joined: Apr 2018
Posts: 1
Likes: 0
From: Iowa
1990 Jaguar XJ12
I have a problem that I can't seem to find the answer to and hopefully someone has experienced it or know what the solution is.
1990 Jaguar XJ12. It started to run rough, almost intermittently, then constantly. After checking plugs, dist cap, plugs etc. I narrowed it down to 3 cylinders on the A bank that were not firing. Tested the connectors in the harness to each cylinder and all were sending a signal to the injectors except the 3 cylinders not firing. I checked to four positive leads coming in to the harness and they all produced a steady signal. The connections that worked on the harness (9 cylinders) produced the pulsating signal while the 3 other ones no signal at all.
I looked and saw many messages that indicated injection harness was the likely problem as they tend to fail from heat etc. and it can cause on bank not to carry the signal.
Bought a new harness and installed .... same problem.
What can it be?? ECU ? bad ground? resistors? What connection or source cam malfunction so that the signal reaching the harness is not functional on only one set in one bank. As you probably know, there are 4 sections/ two in each bank that run a signal to the injectors.. With a know good harness, what can be causing only one series in one bank to not produce a signal.
Thanks and would sincerely appreciate anyone's experience or knowledge.
JB
1990 Jaguar XJ12. It started to run rough, almost intermittently, then constantly. After checking plugs, dist cap, plugs etc. I narrowed it down to 3 cylinders on the A bank that were not firing. Tested the connectors in the harness to each cylinder and all were sending a signal to the injectors except the 3 cylinders not firing. I checked to four positive leads coming in to the harness and they all produced a steady signal. The connections that worked on the harness (9 cylinders) produced the pulsating signal while the 3 other ones no signal at all.
I looked and saw many messages that indicated injection harness was the likely problem as they tend to fail from heat etc. and it can cause on bank not to carry the signal.
Bought a new harness and installed .... same problem.
What can it be?? ECU ? bad ground? resistors? What connection or source cam malfunction so that the signal reaching the harness is not functional on only one set in one bank. As you probably know, there are 4 sections/ two in each bank that run a signal to the injectors.. With a know good harness, what can be causing only one series in one bank to not produce a signal.
Thanks and would sincerely appreciate anyone's experience or knowledge.
JB
Veteran Member
Joined: Mar 2008
Posts: 25,529
Likes: 11,721
From: Pacific Northwest USA
What can it be?? ECU ? bad ground? resistors? What connection or source cam malfunction so that the signal reaching the harness is not functional on only one set in one bank. As you probably know, there are 4 sections/ two in each bank that run a signal to the injectors.. With a know good harness, what can be causing only one series in one bank to not produce a signal.
Thanks and would sincerely appreciate anyone's experience or knowledge.
JB
To clarify, all three inoperative injectors are in the same group? (2a 4a 6a 1a 3a 5a 2b 4b 6b 1b 3b 5b)
I go with a resistor pack problem first. Remove it, clean connections! See what happens. They seldom fail but poor connections are common
Cheers
DD
Joined: Dec 2011
Posts: 120,439
Likes: 17,009
From: Durham, UK
Welcome to the forum JB,
Good to have you with us at Jaguar forums.
Doug has already suggested one possible cause in post #3 Follow this link https://www.jaguarforums.com/forum/x...s-i-ii-iii-16/ to the XJ6 & XJ12 Series I, Ii & III forum for help, advice and information. The 'HOW TO' thread at the top is a good place to start for information on regular issues.
Please remember to add vehicle details to your Signature to help others to give relevant advice. Go to the User CP button on the left of the top menu bar, then Settings & Options under Your Control Panel. Select Edit Signature and enter the details.
You can also visit the US Midwest Region forum by following this link https://www.jaguarforums.com/forum/us-midwest-39/ to find other members in your region.
Enjoy the forums.
Graham
Good to have you with us at Jaguar forums.
Doug has already suggested one possible cause in post #3 Follow this link https://www.jaguarforums.com/forum/x...s-i-ii-iii-16/ to the XJ6 & XJ12 Series I, Ii & III forum for help, advice and information. The 'HOW TO' thread at the top is a good place to start for information on regular issues.
Please remember to add vehicle details to your Signature to help others to give relevant advice. Go to the User CP button on the left of the top menu bar, then Settings & Options under Your Control Panel. Select Edit Signature and enter the details.
You can also visit the US Midwest Region forum by following this link https://www.jaguarforums.com/forum/us-midwest-39/ to find other members in your region.
Enjoy the forums.
Graham
Joined: Oct 2007
Posts: 121,065
Likes: 6,652
From: PHX some of the time
Welcome to Jaguar Forums JB,
Good to have you with us.
Enjoy the forum.
If you haven't done so already you should add your car details to your signature to help others to help you.
If you need help with getting around and using the forum follow this link for some help Forum Help
Good to have you with us.
Enjoy the forum.
If you haven't done so already you should add your car details to your signature to help others to help you.
If you need help with getting around and using the forum follow this link for some help Forum Help
Trending Topics
Thread
Thread Starter
Forum
Replies
Last Post
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)