Help!! Intermittent Engine Failure..XJS
#1
07-20-2007, 01:33 PM
Guest
Posts: n/a
Help!! Intermittent Engine Failure..XJS
We have a 6.0 XJS with one of our Driven Man 6-Speeds that has an intermittent engine failure issue. It seems to quit when run hard and hot, stumbles quite a bit seconds before it quits and runs fine once cool. The car feels starved for fuel when it stumbles. Took the car out on Road Atlanta for a track tour and had to be flat bedded back to the pits after just a couple of laps in very hot weather. I may be attributing more to temperature than needs be, but driving home after Road Atlanta, cruising at low rpm in the evening the car never missed a beat. Anyone have similar issues or a possible solution? Thanks for your help.
#2
07-30-2007, 09:28 AM
#3
07-30-2007, 12:35 PM
Veteran Member
RE: Help!! Intermittent Engine Failure..XJS
There is no XJS forum so posters just put them where they want to. I guess they should be in the "other models" forum, but no big deal.
I would start with a manual fuel pressure gauge to see if you are really losing pressure. You may have a fuel pump that is getting too hot. It sounds to me more like an ignition module or coil, but it's too wide open until a little further testing.
I would start with a manual fuel pressure gauge to see if you are really losing pressure. You may have a fuel pump that is getting too hot. It sounds to me more like an ignition module or coil, but it's too wide open until a little further testing.
#4
07-04-2016, 01:21 PM
Veteran Member
We have a 6.0 XJS with one of our Driven Man 6-Speeds that has an intermittent engine failure issue. It seems to quit when run hard and hot, stumbles quite a bit seconds before it quits and runs fine once cool. The car feels starved for fuel when it stumbles. Took the car out on Road Atlanta for a track tour and had to be flat bedded back to the pits after just a couple of laps in very hot weather. I may be attributing more to temperature than needs be, but driving home after Road Atlanta, cruising at low rpm in the evening the car never missed a beat. Anyone have similar issues or a possible solution? Thanks for your help.
I changed sparks, coils, injectors, nothing helped.
#5
07-04-2016, 02:57 PM
Veteran Member
It turned out it was a faulty wire going to one of the sensors the ECU requires for the car to run. Sorry I don't recall which sensor, but the way I found it was to let the car run and get very warm, then I'd start jiggling wires and the harnesses at various points. Eventually I found the failure point in a section of wire.
The following users liked this post:
xjsv12 (07-05-2016)
#7
07-04-2016, 09:44 PM
Veteran Member
Replace the coolant temperature sensor, the one that feeds the ECU. Once they start to fail (which they do quite quickly) they send errant signals to the ECU and sooner or later you end up with no drive and then no start.
The front crank sensor is only there to give a signal to the ECU to start the car; once the engine is running it serves no further purpose.
The front crank sensor is only there to give a signal to the ECU to start the car; once the engine is running it serves no further purpose.
The following users liked this post:
xjsv12 (07-05-2016)
Trending Topics
#8
07-05-2016, 01:46 AM
Veteran Member
The following users liked this post:
xjsv12 (07-05-2016)
#9
07-05-2016, 05:31 AM
Veteran Member
This is incorrect, the front crank sensor tells the Marelli when piston 1A is at TDC, the Marelli then calculates all ignition events from this pulse in conjunction with the engine speed sensor on the flywheel.
The following users liked this post:
xjsv12 (07-05-2016)
#10
07-05-2016, 05:35 AM
Veteran Member
"The front crank sensor is only there to give a signal to the ECU to start the car; once the engine is running it serves no further purpose."
Here is the 89 XKS supplement which describes the Marelli ignition system. The front sensor on the Marelli is the TDC sensor which controls timing, The rear sensor provides feedback for engine speed. The system simply will not run without either. However, I will say now as I have many times over in many posts.....these things are NOT sensors. They are small electromagnetic generators. The send a AC signal to the Marelli ECU. If the signal is weak or distorted, the car stops running.
http://www.jagrepair.com/images/Elec...Supplement.pdf
Here is the 89 XKS supplement which describes the Marelli ignition system. The front sensor on the Marelli is the TDC sensor which controls timing, The rear sensor provides feedback for engine speed. The system simply will not run without either. However, I will say now as I have many times over in many posts.....these things are NOT sensors. They are small electromagnetic generators. The send a AC signal to the Marelli ECU. If the signal is weak or distorted, the car stops running.
http://www.jagrepair.com/images/Elec...Supplement.pdf
The following 2 users liked this post by superchargedtr6:
Greg in France (07-05-2016),
xjsv12 (07-05-2016)
#11
07-05-2016, 05:39 AM
Veteran Member
We have a 6.0 XJS with one of our Driven Man 6-Speeds that has an intermittent engine failure issue. It seems to quit when run hard and hot, stumbles quite a bit seconds before it quits and runs fine once cool. The car feels starved for fuel when it stumbles. Took the car out on Road Atlanta for a track tour and had to be flat bedded back to the pits after just a couple of laps in very hot weather. I may be attributing more to temperature than needs be, but driving home after Road Atlanta, cruising at low rpm in the evening the car never missed a beat. Anyone have similar issues or a possible solution? Thanks for your help.
What model and is it stock XJS 6.0L or has it been converted from an XJ40/X300 as the ignition systems are different.
There are too many small differences between all the iterations of the V12 to make any recommendations, apart from check ALL the wiring and connections to all sensors.
The following 2 users liked this post by warrjon:
Greg in France (07-05-2016),
xjsv12 (07-05-2016)
#12
07-05-2016, 06:41 AM
Veteran Member
As Greg said
What model and is it stock XJS 6.0L or has it been converted from an XJ40/X300 as the ignition systems are different.
There are too many small differences between all the iterations of the V12 to make any recommendations, apart from check ALL the wiring and connections to all sensors.
What model and is it stock XJS 6.0L or has it been converted from an XJ40/X300 as the ignition systems are different.
There are too many small differences between all the iterations of the V12 to make any recommendations, apart from check ALL the wiring and connections to all sensors.
Greg
The following users liked this post:
xjsv12 (07-05-2016)
#13
07-05-2016, 02:26 PM
Veteran Member
Thanks for answers friends
Robert Hall's answer:
Hello Nikolai!
I remember you! I hope all is well.
The 6.0 cars have 2 fuel pumps. One for less than 2500 RPM and the other for more than 2500
My car was losing the flow from the low RPM pump. I replaced the pump and problem went away.
Thank you,
Robert Hall
The Driven Man - Improving Classic Cars
American Powertrain - More Gears More Fun
931-646-4836
Jaguar Performance Parts & Classic Car Performance - The Driven Man
Specialty Performance Parts, 5 and 6 speed Transmission Conversions and Accessories | American Power Train
Robert Hall's answer:
Hello Nikolai!
I remember you! I hope all is well.
The 6.0 cars have 2 fuel pumps. One for less than 2500 RPM and the other for more than 2500
My car was losing the flow from the low RPM pump. I replaced the pump and problem went away.
Thank you,
Robert Hall
The Driven Man - Improving Classic Cars
American Powertrain - More Gears More Fun
931-646-4836
Jaguar Performance Parts & Classic Car Performance - The Driven Man
Specialty Performance Parts, 5 and 6 speed Transmission Conversions and Accessories | American Power Train
Last edited by xjsv12; 07-05-2016 at 03:04 PM.
#14
07-05-2016, 03:01 PM
Veteran Member
#15
07-05-2016, 04:09 PM
Veteran Member
This fault happened a year ago, as I understood it.
Ignition coil A bank failed at a speed of 100 km\h.
While I understood what happened, until I stopped, the catalyst is taken off on the road, exhaust pipe melted.
I disconnected the right injectors and drove ten kilometers to the workshop. Where I replaced the coil, spark plugs and catalyst.
After that I began to feel infrequent, non noticeable, like misfires. These misfires had a slow progress.
In this season very noticeable at rpm between 1000 and 2000 on the third and top gear with a light throttle.
Ignition coil A bank failed at a speed of 100 km\h.
While I understood what happened, until I stopped, the catalyst is taken off on the road, exhaust pipe melted.
I disconnected the right injectors and drove ten kilometers to the workshop. Where I replaced the coil, spark plugs and catalyst.
After that I began to feel infrequent, non noticeable, like misfires. These misfires had a slow progress.
In this season very noticeable at rpm between 1000 and 2000 on the third and top gear with a light throttle.
#16
07-06-2016, 02:43 AM
Veteran Member
This fault happened a year ago, as I understood it.
Ignition coil A bank failed at a speed of 100 km\h.
While I understood what happened, until I stopped, the catalyst is taken off on the road, exhaust pipe melted.
I disconnected the right injectors and drove ten kilometers to the workshop. Where I replaced the coil, spark plugs and catalyst.
After that I began to feel infrequent, non noticeable, like misfires. These misfires had a slow progress.
In this season very noticeable at rpm between 1000 and 2000 on the third and top gear with a light throttle.
Ignition coil A bank failed at a speed of 100 km\h.
While I understood what happened, until I stopped, the catalyst is taken off on the road, exhaust pipe melted.
I disconnected the right injectors and drove ten kilometers to the workshop. Where I replaced the coil, spark plugs and catalyst.
After that I began to feel infrequent, non noticeable, like misfires. These misfires had a slow progress.
In this season very noticeable at rpm between 1000 and 2000 on the third and top gear with a light throttle.
I have heard (do not know) that there can be a honeycomb-type thing in the exhaust manifold or downpipe, if yours has this, maybe you have a blockage there?
Greg
The following users liked this post:
xjsv12 (07-06-2016)
#17
07-06-2016, 02:55 PM
Veteran Member
After the catalyst has nothing, straight pipe 76mm (3.0").
I will measure the fuel pressure under load, after tomorrow.
I ordered a crankshaft sensor, both.
#18
07-07-2016, 01:40 AM
Veteran Member
Have you renewed the dizzy cap, rotor and leads?
Also, have you tried swapping the amps to see if the fault moves? Also, worth renewing the amp leads to the dizzy/coil, I seem to recall someone posting about an intermittent fault that turned out to be in thiss bit of the system.
Greg
Also, have you tried swapping the amps to see if the fault moves? Also, worth renewing the amp leads to the dizzy/coil, I seem to recall someone posting about an intermittent fault that turned out to be in thiss bit of the system.
Greg
#19
07-07-2016, 07:30 AM
Veteran Member
Have you renewed the dizzy cap, rotor and leads?
Also, have you tried swapping the amps to see if the fault moves? Also, worth renewing the amp leads to the dizzy/coil, I seem to recall someone posting about an intermittent fault that turned out to be in thiss bit of the system.
Greg
Also, have you tried swapping the amps to see if the fault moves? Also, worth renewing the amp leads to the dizzy/coil, I seem to recall someone posting about an intermittent fault that turned out to be in thiss bit of the system.
Greg
I have amplifiers, will check it tomorrow with fuel pressure.