Marelli ignition failure
#1
Marelli ignition failure
I'm posting this more as a precautionary measure for future XJS owners. This is the second time I've suffered the infamous Marelli rotor failure. First time it resulted in a near catastrophic engine fire. Mechanic wanted $6k + to replace all the under hood wiring and rubber. Car sat forever.
Fast forward several years, and I buy a damn near identical 89.5 XJS V12, black on black. It performed flawlessly for a year. Then one day, on the way home, the power just disappears. The car is running smoothly, just seriously down on power. I smell gas. It won't rev above 3.5k. It shifts into 3rd hard, at a max speed of about 50 MPH. I've been here before.
I was only a couple of blocks from the house, so I drove in and parked it. Ordered a cap & rotor (christ the cap is half the weight of the genuine Marelli item, but I couldn't find one). Applied the silicone sealant to the rotor base per Kirby Palm's instructions.
Gawd bless she runs like a scalded cat again... easy to get sideways. Let me tell you guys this. Living in a small town, when this happened the first time, they charged me $1k+ to diagnose then fix the problem (there was no Jag mechanic). This is a half hour fix. I am NOT a mechanic. It was easy as pie to move the cruise control, unplug the coil and spark plug leads, unscrew the distributor, apply some WD40 to the rotor screws, then unscrew that.
The rotor was thoroughly burned - will attach a pic. Applied silicone sealant to the new one, screwed it in place, dropped in new distributor cap, reattached wires, fired it up.
She blew copious amounts of smoke from the passenger exhaust pipe for a good 3 minutes. Probably all the unburnt fuel dumped into the cats, etc.
What I'm trying to say is this: Many beautiful XJSs will go up in flames due to ignorance. Utilise the knowledge in Kirby Palm's book, the various XJS fora. The weak spots of this car are well documented. Stay ahead of the curve on maintenance, and when something goes wrong, undoubtedly it has happened to someone else before. Find out what it is, fix it, and keep a legendary automobile on the road.
Cheers.
Fast forward several years, and I buy a damn near identical 89.5 XJS V12, black on black. It performed flawlessly for a year. Then one day, on the way home, the power just disappears. The car is running smoothly, just seriously down on power. I smell gas. It won't rev above 3.5k. It shifts into 3rd hard, at a max speed of about 50 MPH. I've been here before.
I was only a couple of blocks from the house, so I drove in and parked it. Ordered a cap & rotor (christ the cap is half the weight of the genuine Marelli item, but I couldn't find one). Applied the silicone sealant to the rotor base per Kirby Palm's instructions.
Gawd bless she runs like a scalded cat again... easy to get sideways. Let me tell you guys this. Living in a small town, when this happened the first time, they charged me $1k+ to diagnose then fix the problem (there was no Jag mechanic). This is a half hour fix. I am NOT a mechanic. It was easy as pie to move the cruise control, unplug the coil and spark plug leads, unscrew the distributor, apply some WD40 to the rotor screws, then unscrew that.
The rotor was thoroughly burned - will attach a pic. Applied silicone sealant to the new one, screwed it in place, dropped in new distributor cap, reattached wires, fired it up.
She blew copious amounts of smoke from the passenger exhaust pipe for a good 3 minutes. Probably all the unburnt fuel dumped into the cats, etc.
What I'm trying to say is this: Many beautiful XJSs will go up in flames due to ignorance. Utilise the knowledge in Kirby Palm's book, the various XJS fora. The weak spots of this car are well documented. Stay ahead of the curve on maintenance, and when something goes wrong, undoubtedly it has happened to someone else before. Find out what it is, fix it, and keep a legendary automobile on the road.
Cheers.
#2
Join Date: Mar 2008
Location: Pacific Northwest USA
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Good post, good advice
As of about a year ago the bona fide Marelli rotor was still available under the Jaguar part number. The true Marelli cap, though, has apparently been out of production for a couple years at least.
My limited research revealed an aftermarket "Made in Italy" cap...no other markings...being sold under various labels/brand names.
Cheers
DD
As of about a year ago the bona fide Marelli rotor was still available under the Jaguar part number. The true Marelli cap, though, has apparently been out of production for a couple years at least.
My limited research revealed an aftermarket "Made in Italy" cap...no other markings...being sold under various labels/brand names.
Cheers
DD
#3
#5
#7
@Flint
Good post and good advice. I too have had the failure (Was Bank B coil in my case) and even though I had thoroughly read up on everything about Marelli failures (I already had a new cap and rotor) my brain didn't register what was happening until I had driven the car about 1 mile back home. It was just down on power, nothing more. Because of the firing order of the V12, as you will know, the car just runs quite smoothly, albeit with a very low idle on only 6 cylinders on one bank.
By the time I got the car home, the front cat was so hot it had set the steering rack boot on fire (This is not a normal failure and I think is unique to my car, mainly because the PO mucked about with it so much, including fitting different cats from god knows what, and also removing the heat shields that are supposed to protect the steering rack boots in the first place) Luckily I always carry fire extinguishers in my cars so I got the fire out reasonably quickly. A new coil (actually 2 new coils) and a steering rack boot later, all was well again...... but it was pretty scary.
My cruise control is currently the last thing not working on my car (I finally have A/C again, with a working center vent, woohoo!) but I am hesitant to fix the cruise control as I worry about having another failure and not knowing about it because my foot isn't on the gas pedal. Anyway, the more we type these things up, the less chance for other XJS owners to get caught out.....
Good post and good advice. I too have had the failure (Was Bank B coil in my case) and even though I had thoroughly read up on everything about Marelli failures (I already had a new cap and rotor) my brain didn't register what was happening until I had driven the car about 1 mile back home. It was just down on power, nothing more. Because of the firing order of the V12, as you will know, the car just runs quite smoothly, albeit with a very low idle on only 6 cylinders on one bank.
By the time I got the car home, the front cat was so hot it had set the steering rack boot on fire (This is not a normal failure and I think is unique to my car, mainly because the PO mucked about with it so much, including fitting different cats from god knows what, and also removing the heat shields that are supposed to protect the steering rack boots in the first place) Luckily I always carry fire extinguishers in my cars so I got the fire out reasonably quickly. A new coil (actually 2 new coils) and a steering rack boot later, all was well again...... but it was pretty scary.
My cruise control is currently the last thing not working on my car (I finally have A/C again, with a working center vent, woohoo!) but I am hesitant to fix the cruise control as I worry about having another failure and not knowing about it because my foot isn't on the gas pedal. Anyway, the more we type these things up, the less chance for other XJS owners to get caught out.....
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#8
I am not a fan of cruise control, and would like to clean up the V. As soon as I find a good writeup on how to safely remove the bellows, that is my next project.
Must be nice to have everything working except your cruise! I still have a ways to go.
#9
@Flint
Yes, it's taken me almost 3 years to get to where I am now, and it'll never be a show car, but it's mine and it's my elbow grease and it's worth it.
Go for the growlers......
Fabulous sound. Not noticeable or intrusive on light throttle or at idle but put your foot down and the thing positively........erm...... growls I guess !
Also didn't give me any Check Engine lights. My 92 has the beginnings of OBD where it can show basic FF (Fuel Fault codes)
Yes, it's taken me almost 3 years to get to where I am now, and it'll never be a show car, but it's mine and it's my elbow grease and it's worth it.
Go for the growlers......
Fabulous sound. Not noticeable or intrusive on light throttle or at idle but put your foot down and the thing positively........erm...... growls I guess !
Also didn't give me any Check Engine lights. My 92 has the beginnings of OBD where it can show basic FF (Fuel Fault codes)
#10
Guest
Posts: n/a
1989 XJS mirelli ignition problem
In troubleshooting my mirelli system. It is running on B bank only. swapped coils and amps to test each. all seemed to work. Same voltages on both coils. No spark on A bank, or the coil wire feeding A bank. Tested using the pickup on my timing light. The rotor did not look bad. but is this the cuprit, or do i have a problem with crank speed sensors?
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