Poor performance
#1
Poor performance
Okay, I have a 1994 6.0 L V-12. It runs/idles well, but has no power, like it's running on 6 cylinders. Definite fuel smell also when driving. The exhaust on right side at the tailpipe is much hotter than the left, although I can feel exhaust coming out both sides. Ideas? Can someone point me in the right direction?
Thanks,
Bill
Thanks,
Bill
#2
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 24,772
Received 10,815 Likes
on
7,122 Posts
#3
Unless you want it to burst into flames.
How old is your ignition system? coils/amps/dist cables etc? There are some fairly simple ways to identify which part is weak and starting to fail, swap the electrical plugs on your ignition coils and see if the exhaust is cooler on a different side for example.
Or alternatively spare yourself the headache and/or fire hazard and just do it all once with a complete set of new ignition parts.
VE520225 Cambiare is a good interchange part for the ignition modules, and if your coils are the type with the nipple inside the socket I have a new set that was incompatible with my cables.
How old is your ignition system? coils/amps/dist cables etc? There are some fairly simple ways to identify which part is weak and starting to fail, swap the electrical plugs on your ignition coils and see if the exhaust is cooler on a different side for example.
Or alternatively spare yourself the headache and/or fire hazard and just do it all once with a complete set of new ignition parts.
VE520225 Cambiare is a good interchange part for the ignition modules, and if your coils are the type with the nipple inside the socket I have a new set that was incompatible with my cables.
#4
Thanks, guys. I have just replaced the spark plugs, dist cap, rotor, HT leads. There may be an issue with the exhaust/cats. Still not sure what the problem is.... I'm going to have it towed to my favorite shop and let them diagnose the problem. I'm also going to have them install a custom exhaust. Since I'm in SC, don't need to run the cats at all.
#5
Thanks, guys. I have just replaced the spark plugs, dist cap, rotor, HT leads. There may be an issue with the exhaust/cats. Still not sure what the problem is.... I'm going to have it towed to my favorite shop and let them diagnose the problem. I'm also going to have them install a custom exhaust. Since I'm in SC, don't need to run the cats at all.
#6
Hi drbill
Following on from what 'Greg' said inside the 'Marelli' Distro Cap is a Double Stepped Rotor
'A Rotor Arm that is stepped with a blade at each end'
So although the Blades are at opposite ends, they sort of sit one on top of the other
One end of the Rotor runs the 6 cylinders on 'A' Bank
The other end of the Rotor runs the 6 cylinders on 'B' Bank
So as 'Doug' said, its just like having Two 6 Cylinder Engines which are joined together
What can happen and may have happened in your case
Is that the Insulation between the upper Blade on one end of the Rotor (The Top one in the joined together Step)
May have broken down and allowed the HT to Track to Ground via the Distro Spindle, which would disable all the Cylinders on 'A' Bank
At which point you would now be running on only half the Engine but the V12 Engine is so smooth that even running on just 6 cylinders
It may take a little while to even notice it apart from having a sudden loss of power
So assuming 'A' Bank has shut down (in which case stop and turn off the Ignition ASAP!)
Raw Fuel will still continue to be Pumped in to 'A' Bank (or which ever side has now shut down)
Which would then send unburned Petrol into the Hot exhaust of which ever Bank of Cylinders is no longer running
Where in the event this happens then it could cause a fire!
Always carry a Fire Extinguisher in an XJS
Although there are a couple of other things that could cause a Bank of Cylinders in the Engine to shut down, one of which is Coil Failure
Of One of the Two Coils on a 'Marelli' System Car
Don't try swapping the Plugs on the Coils as the Engine won't Start (ask me how I know!)
Or the Failure of one of the Banks of Cylinders on the Engine could be down to
One of the Two Ignition Amplifiers on the Closing Panel over the Rad
There 'was' a know issue on 'some' of the 6 Litre XJS that the Bonnet/Hood Lining could 'Push Down'
On one of the Ignition Amplifiers causing a possible failure over time
I think there was a Service Bulletin issued as to where it could be relocated to prevent it causing a problem (Doug would probably know)
Following on from what 'Greg' said inside the 'Marelli' Distro Cap is a Double Stepped Rotor
'A Rotor Arm that is stepped with a blade at each end'
So although the Blades are at opposite ends, they sort of sit one on top of the other
One end of the Rotor runs the 6 cylinders on 'A' Bank
The other end of the Rotor runs the 6 cylinders on 'B' Bank
So as 'Doug' said, its just like having Two 6 Cylinder Engines which are joined together
What can happen and may have happened in your case
Is that the Insulation between the upper Blade on one end of the Rotor (The Top one in the joined together Step)
May have broken down and allowed the HT to Track to Ground via the Distro Spindle, which would disable all the Cylinders on 'A' Bank
At which point you would now be running on only half the Engine but the V12 Engine is so smooth that even running on just 6 cylinders
It may take a little while to even notice it apart from having a sudden loss of power
So assuming 'A' Bank has shut down (in which case stop and turn off the Ignition ASAP!)
Raw Fuel will still continue to be Pumped in to 'A' Bank (or which ever side has now shut down)
Which would then send unburned Petrol into the Hot exhaust of which ever Bank of Cylinders is no longer running
Where in the event this happens then it could cause a fire!
Always carry a Fire Extinguisher in an XJS
Although there are a couple of other things that could cause a Bank of Cylinders in the Engine to shut down, one of which is Coil Failure
Of One of the Two Coils on a 'Marelli' System Car
Don't try swapping the Plugs on the Coils as the Engine won't Start (ask me how I know!)
Or the Failure of one of the Banks of Cylinders on the Engine could be down to
One of the Two Ignition Amplifiers on the Closing Panel over the Rad
There 'was' a know issue on 'some' of the 6 Litre XJS that the Bonnet/Hood Lining could 'Push Down'
On one of the Ignition Amplifiers causing a possible failure over time
I think there was a Service Bulletin issued as to where it could be relocated to prevent it causing a problem (Doug would probably know)
Last edited by orangeblossom; 03-17-2018 at 04:41 AM.
The following users liked this post:
Greg in France (03-17-2018)
#7
Hi drbill
Following on from what 'Greg' said inside the 'Marelli' Distro Cap is a Double Stepped Rotor
'A Rotor Arm that is stepped with a blade at each end'
So although the Blades are at opposite ends, they sort of sit one on top of the other
One end of the Rotor runs the 6 cylinders on 'A' Bank
The other end of the Rotor runs the 6 cylinders on 'B' Bank
So as 'Doug' said, its just like having Two 6 Cylinder Engines which are joined together
What can happen and may have happened in your case
Is that the Insulation between the upper Blade on one end of the Rotor (The Top one in the joined together Step)
May have broken down and allowed the HT to Track to Ground via the Distro Spindle, which would disable all the Cylinders on 'A' Bank
At which point you would now be running on only half the Engine but the V12 Engine is so smooth that even running on just 6 cylinders
It may take a little while to even notice it apart from having a sudden loss of power
So assuming 'A' Bank has shut down (in which case stop and turn off the Ignition ASAP!)
Raw Fuel will still continue to be Pumped in to 'A' Bank (or which ever side has now shut down)
Which would then send unburned Petrol into the Hot exhaust of which ever Bank of Cylinders is no longer running
Where in the event this happens then it could cause a fire!
Always carry a Fire Extinguisher in an XJS
Although there are a couple of other things that could cause a Bank of Cylinders in the Engine to shut down, one of which is Coil Failure
Of One of the Two Coils on a 'Marelli' System Car
Don't try swapping the Plugs on the Coils as the Engine won't Start (ask me how I know!)
Or the Failure of one of the Banks of Cylinders on the Engine could be down to
One of the Two Ignition Amplifiers on the Closing Panel over the Rad
There 'was' a know issue on 'some' of the 6 Litre XJS that the Bonnet/Hood Lining could 'Push Down'
On one of the Ignition Amplifiers causing a possible failure over time
I think there was a Service Bulletin issued as to where it could be relocated to prevent it causing a problem (Doug would probably know)
Following on from what 'Greg' said inside the 'Marelli' Distro Cap is a Double Stepped Rotor
'A Rotor Arm that is stepped with a blade at each end'
So although the Blades are at opposite ends, they sort of sit one on top of the other
One end of the Rotor runs the 6 cylinders on 'A' Bank
The other end of the Rotor runs the 6 cylinders on 'B' Bank
So as 'Doug' said, its just like having Two 6 Cylinder Engines which are joined together
What can happen and may have happened in your case
Is that the Insulation between the upper Blade on one end of the Rotor (The Top one in the joined together Step)
May have broken down and allowed the HT to Track to Ground via the Distro Spindle, which would disable all the Cylinders on 'A' Bank
At which point you would now be running on only half the Engine but the V12 Engine is so smooth that even running on just 6 cylinders
It may take a little while to even notice it apart from having a sudden loss of power
So assuming 'A' Bank has shut down (in which case stop and turn off the Ignition ASAP!)
Raw Fuel will still continue to be Pumped in to 'A' Bank (or which ever side has now shut down)
Which would then send unburned Petrol into the Hot exhaust of which ever Bank of Cylinders is no longer running
Where in the event this happens then it could cause a fire!
Always carry a Fire Extinguisher in an XJS
Although there are a couple of other things that could cause a Bank of Cylinders in the Engine to shut down, one of which is Coil Failure
Of One of the Two Coils on a 'Marelli' System Car
Don't try swapping the Plugs on the Coils as the Engine won't Start (ask me how I know!)
Or the Failure of one of the Banks of Cylinders on the Engine could be down to
One of the Two Ignition Amplifiers on the Closing Panel over the Rad
There 'was' a know issue on 'some' of the 6 Litre XJS that the Bonnet/Hood Lining could 'Push Down'
On one of the Ignition Amplifiers causing a possible failure over time
I think there was a Service Bulletin issued as to where it could be relocated to prevent it causing a problem (Doug would probably know)
Trending Topics
#8
#9
Join Date: Jul 2012
Location: Walnut Creek, California
Posts: 6,796
Received 2,399 Likes
on
1,880 Posts
Super !!! Oh, how I wish I was free of inspections. but, I got both my cars through !!!
Go shopping and fid a muffler shop in your area that builds custom systems, for the hot rod and muscle car folks. Not bound by mere replacements.
A talented one can redo it from the manifolds on back. X or H pipe, Turbo type mufflers, aye or nay on the rear resonators and an under the cage route. Sans cats means a bit on performance and a lot on $'s.
Carl
Go shopping and fid a muffler shop in your area that builds custom systems, for the hot rod and muscle car folks. Not bound by mere replacements.
A talented one can redo it from the manifolds on back. X or H pipe, Turbo type mufflers, aye or nay on the rear resonators and an under the cage route. Sans cats means a bit on performance and a lot on $'s.
Carl
#10
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 24,772
Received 10,815 Likes
on
7,122 Posts
I do have another question: has anyone upgraded their exhaust for one of these 6.0 liter cars? Since I'm in SC, no inspection, so I can pretty much do whatever I want..... thanks for all the help!
Many have gone to lower restriction systems to pick up a couple horsepower and a sportier exhaust tone....the later sometimes problematic on the Jag V12, which can end up sounding a bit odd and nothing like the exotic Italian V12s
Cheers
DD
#11
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 24,772
Received 10,815 Likes
on
7,122 Posts
I've attached a pic of the x-pipe arrangement I had built for my V12. Not seen are the rear resonators. I am happy with the sound; much better than my other V12 which didn't have the x-pipe but was otherwise similar
Cheers
DD
#12
I've got straight pipe (side exits) that work fantastic on the highway, neighbours complained so I had to do high-flow mufflers which isn't as nice but overall from my exhaustive research into the subject the best thing after gutting/removing the Cats is to retain the entire system as a straight pipe setup (with x-pipe preferably) leading to the rear resonators.
Delete all the cat/muffler garbage in the middle but keep the last two units for that raspy V12 sound otherwise you'll end up like me with people asking if I put a chevy 350 engine in there.
Delete all the cat/muffler garbage in the middle but keep the last two units for that raspy V12 sound otherwise you'll end up like me with people asking if I put a chevy 350 engine in there.
#13
Great input; just what I was looking for. We have a couple of shops there who can do the job. I'll show them that picture; want to try to get the "right" sound. Don't want anyone complaining about the loudness, just a nice rumble.
Thanks,
Bill
#14
#15
That's a bit lairy, is he running on slicks?
Mine has the centre boxes removed and TWR quad tailpipes; not add ons but proper silencers (mufflers) with twin pipes.
Sounds really good but not loud enough to annoy the neighbours.
I also have twin intake air filters which give a slight increase in induction noise.
Mine has the centre boxes removed and TWR quad tailpipes; not add ons but proper silencers (mufflers) with twin pipes.
Sounds really good but not loud enough to annoy the neighbours.
I also have twin intake air filters which give a slight increase in induction noise.
#16
https://m.youtube.com/watch?v=70nyn9LH_bQ
Found it..this is what I mean by retaining that raspy v12 noise. This guy has straight pipes with rear resonators and better air intake but thats mostly beside the point.
Found it..this is what I mean by retaining that raspy v12 noise. This guy has straight pipes with rear resonators and better air intake but thats mostly beside the point.
#17
That's a bit lairy, is he running on slicks?
Mine has the centre boxes removed and TWR quad tailpipes; not add ons but proper silencers (mufflers) with twin pipes.
Sounds really good but not loud enough to annoy the neighbours.
I also have twin intake air filters which give a slight increase in induction noise.
Mine has the centre boxes removed and TWR quad tailpipes; not add ons but proper silencers (mufflers) with twin pipes.
Sounds really good but not loud enough to annoy the neighbours.
I also have twin intake air filters which give a slight increase in induction noise.
Thanks!
#18
#19
Simply Performance make the pipes so that they are a straight swap for the under car silencer boxes.
Use this link and scroll down to see them:
Performance parts |
#20
As Steve mentioned, removing the centre boxes and replacing them by pipes, while leaving the rear tunnel silencers in place, gives much more sound, and is a very easy thing to do.
Simply Performance make the pipes so that they are a straight swap for the under car silencer boxes.
Use this link and scroll down to see them:
Performance parts |
Simply Performance make the pipes so that they are a straight swap for the under car silencer boxes.
Use this link and scroll down to see them:
Performance parts |