Another Marelli Ignition Caused Engine Fire?
#21
A card to the exhaust isn't foolproof because if one bank isn't firing, it will still be pumping air/fuel mixture through it, albeit at a much reduced volume to the functioning side.
Listsning to injectors won't tell you if the plugs are firing either - that's the problem, the injectors pumping fuel into a non-firing cylinder just pushes combustible mixture into the cat.
If you have a misfire on one or two cylinders you are unlikely to be able to detect it unless you are very sensitive to vibration and noise. If you have a whole bank out, you are unlikely not to notice unless you are completely unaware of what's happening around you.
Listsning to injectors won't tell you if the plugs are firing either - that's the problem, the injectors pumping fuel into a non-firing cylinder just pushes combustible mixture into the cat.
If you have a misfire on one or two cylinders you are unlikely to be able to detect it unless you are very sensitive to vibration and noise. If you have a whole bank out, you are unlikely not to notice unless you are completely unaware of what's happening around you.
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orangeblossom (05-10-2018)
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Wow, if you can detect a pause in the pulses you have my respect. If the car is ilding at 1000rpm (and it's probably more like 1200 when cold) each bank of 6 is exhausting spent gas 50 times per second, so you're detecting a 1/50th of a second pause from a single missing cylinder!
#27
Wow, if you can detect a pause in the pulses you have my respect. If the car is ilding at 1000rpm (and it's probably more like 1200 when cold) each bank of 6 is exhausting spent gas 50 times per second, so you're detecting a 1/50th of a second pause from a single missing cylinder!
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Greg in France (05-11-2018)
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#30
It might be an idea to list ways to detect if the V12 isn't running on all twelve cylinders.
Offhand, I think holding a card to the exhaust pipes works, or listening to the injectors clicking by holding a long screwdriver against them and your ear, but these aren't terribly useful while actually cruising down the road at high speed. Or any speed, really....
Offhand, I think holding a card to the exhaust pipes works, or listening to the injectors clicking by holding a long screwdriver against them and your ear, but these aren't terribly useful while actually cruising down the road at high speed. Or any speed, really....
Or even at the coils? Atleast you'd know if a bank failed?
Also as for the Cats http://simplyperformance.com hand-makes proper downpipe replacements, pricey but nice.
#31
I remember a gadget on sale way back in the 70's ; composed of LEDs fired by a wire/coil round the HT leads. But even with only four cyclinders this lacked elegance .
But what could this tell you ?
A bank has failed ? believe me , you know that already !
Another consideration to take into account is how long have you got with this fault before the catalytic converter is converting no longer ? I have read that it is only seconds.
Has anyone an authorative answer to this ?
If you only have seconds you would need electronics sensing the actual spark to stop the injection. Or even better , a fail safe system : not stopping the injection. But it would be yet another thing to go wrong.
But what could this tell you ?
A bank has failed ? believe me , you know that already !
Another consideration to take into account is how long have you got with this fault before the catalytic converter is converting no longer ? I have read that it is only seconds.
Has anyone an authorative answer to this ?
If you only have seconds you would need electronics sensing the actual spark to stop the injection. Or even better , a fail safe system : not stopping the injection. But it would be yet another thing to go wrong.
#33
#34
Or even easier... just buy a Japan-market one that already comes with an exhaust temperature warning light. (^_^)
(I actually don't know for certain that this does in fact do the same thing, but seeing as it went on when one of my coils went out, I assume it does.)
(I actually don't know for certain that this does in fact do the same thing, but seeing as it went on when one of my coils went out, I assume it does.)
I would say easiest is having already bought a cat-less XJS. Can’t set what you don’t have on fire. Reaming out the cats works. I don’t detect a drone from the change, myself. New cat-less downpipes is better, but more $.
Best, of course, is regular maintainance.
#35
To be serious for a moment, it's actually quite easy to buy a Japan-market XJS even if you don't live here. Apparently a lot of Brits buy them, as they're generally a lot more rust-free, and there's plenty with the steering wheel on the wrong side for those rebellious colonists.
Removing the cats, however, is not an option in places where they have strict emissions testing. ::Sad Face::
Your last sentence, though, is quite right.
Removing the cats, however, is not an option in places where they have strict emissions testing. ::Sad Face::
Your last sentence, though, is quite right.
#36
Wow, if you can detect a pause in the pulses you have my respect. If the car is ilding at 1000rpm (and it's probably more like 1200 when cold) each bank of 6 is exhausting spent gas 50 times per second, so you're detecting a 1/50th of a second pause from a single missing cylinder!
If the whole bank goes down then the air exiting the exhaust will not be hot.
#37
I've had an inspiration!
Wouldn't a car with the airpump pipes removed be an ideal candidate for a series of (12) sensors which would allow access to the combustion chamber without cutting and drillings? A series of small sensor probes leading back to a LCD panel gauge in the car somewhere.
Would pressure sensors be the right 'instrument' to detect a troubled sparkplug or misfiring injector? or EGT (exhaust gas temp) type sensors?
Wouldn't a car with the airpump pipes removed be an ideal candidate for a series of (12) sensors which would allow access to the combustion chamber without cutting and drillings? A series of small sensor probes leading back to a LCD panel gauge in the car somewhere.
Would pressure sensors be the right 'instrument' to detect a troubled sparkplug or misfiring injector? or EGT (exhaust gas temp) type sensors?
#38
I've had an inspiration!
Wouldn't a car with the airpump pipes removed be an ideal candidate for a series of (12) sensors which would allow access to the combustion chamber without cutting and drillings? A series of small sensor probes leading back to a LCD panel gauge in the car somewhere.
Wouldn't a car with the airpump pipes removed be an ideal candidate for a series of (12) sensors which would allow access to the combustion chamber without cutting and drillings? A series of small sensor probes leading back to a LCD panel gauge in the car somewhere.
A 12 channel meter isn’t available. Three, four channel units is silly. Twelve gauges more so! I’d go for a single gauge and a 12 position rotary dial switch. You could spin it to check all cylinders!
Some electronic solution with adjustable ranges and alarms / switched outputs probably exists..
Last edited by JigJag; 05-14-2018 at 07:49 PM.
#39
I've had an inspiration!
Wouldn't a car with the airpump pipes removed be an ideal candidate for a series of (12) sensors which would allow access to the combustion chamber without cutting and drillings? A series of small sensor probes leading back to a LCD panel gauge in the car somewhere.
Would pressure sensors be the right 'instrument' to detect a troubled sparkplug or misfiring injector? or EGT (exhaust gas temp) type sensors?
Wouldn't a car with the airpump pipes removed be an ideal candidate for a series of (12) sensors which would allow access to the combustion chamber without cutting and drillings? A series of small sensor probes leading back to a LCD panel gauge in the car somewhere.
Would pressure sensors be the right 'instrument' to detect a troubled sparkplug or misfiring injector? or EGT (exhaust gas temp) type sensors?
#40