Not getting fire. (88 xjs v12)
#1
03-22-2016, 02:42 PM
Not getting fire. (88 xjs v12)
Have a 88' xjs v12 that will not get any fire no matter what I've tried. Tested everything electronic besides the ECU. There is water damage (white mildew) all over the motor and the ecu. Me and my buddy and stumped. Only thing that seems strange is that there is 18ohms from the plugins to the side of the ignition amplifier. Any ideas?
#2
03-22-2016, 05:39 PM
Welcome first and foremost. Please do an intro in the "New Members Area" when time permits.
No idea of your area, as you do not mention it, and some markets do vary with stuff, but the basics of the V12 are:
The fuel and ignition systems are TOTALLY seperate. The ECU in the boot is for fuel only. The "Black Box" on the LH inlet manifold is for spark/tacho.
BUT, and there is always a BUT. There is a shielded wire that runs from that amp to Pin 18 of the ECU, and that supplies a pulse signal to the ECU to inform it that there is ignition activity and its time to wake up the injectors etc.
Second BUT, that wire is by-passed during cranking so the ECU does its fuel thing for initial starting, but as soon as cranking ceases that shielded wire is the only communication for continual running, and that wire BREAKS.
You have 2 ign coils, one in the V, one out the front on the LH side in front of the radiator. They fail, surprised? There is an upgrade to a single coil system, but for now ensure both coiuls are reading 1.2ohms across the +ve and -ver terminals, (or thereabouts) with NOTHING connected to them.
The coil in the V has a 12v IGN feed wire attached, make sure you got 12v IGN to the +ve of that coil, AND, that the 12v remains whilst cranking is happening, coz the Ignition Switch electrical section can drop signal due to old age.
Then, remove the coil HT lead from the cap, and crank it, and observe spark OUT of the coil as the first step. If ya got that, goodo. Then check the easiest HT lead AT the spark plug. If that is a no-go, remove the cap, CAREFULLY, and check the carbon brush at the centre post, they do go AWOL at times.
NEXT.
Inside that amp is a module, GM unit, and they can be flaky at times, BUT, here we go again, you will notice a "condensor" looking cylinder tucked in the corner, with a lead to one of the +ver terminals of that module, REMOVE it, throw it away. They leak to earth, and kill the system in a heartbeat.
Thats enough for now, lets know how you go. These systems are SIMPLE, but you must be thorough and systematic with it.
No idea of your area, as you do not mention it, and some markets do vary with stuff, but the basics of the V12 are:
The fuel and ignition systems are TOTALLY seperate. The ECU in the boot is for fuel only. The "Black Box" on the LH inlet manifold is for spark/tacho.
BUT, and there is always a BUT. There is a shielded wire that runs from that amp to Pin 18 of the ECU, and that supplies a pulse signal to the ECU to inform it that there is ignition activity and its time to wake up the injectors etc.
Second BUT, that wire is by-passed during cranking so the ECU does its fuel thing for initial starting, but as soon as cranking ceases that shielded wire is the only communication for continual running, and that wire BREAKS.
You have 2 ign coils, one in the V, one out the front on the LH side in front of the radiator. They fail, surprised? There is an upgrade to a single coil system, but for now ensure both coiuls are reading 1.2ohms across the +ve and -ver terminals, (or thereabouts) with NOTHING connected to them.
The coil in the V has a 12v IGN feed wire attached, make sure you got 12v IGN to the +ve of that coil, AND, that the 12v remains whilst cranking is happening, coz the Ignition Switch electrical section can drop signal due to old age.
Then, remove the coil HT lead from the cap, and crank it, and observe spark OUT of the coil as the first step. If ya got that, goodo. Then check the easiest HT lead AT the spark plug. If that is a no-go, remove the cap, CAREFULLY, and check the carbon brush at the centre post, they do go AWOL at times.
NEXT.
Inside that amp is a module, GM unit, and they can be flaky at times, BUT, here we go again, you will notice a "condensor" looking cylinder tucked in the corner, with a lead to one of the +ver terminals of that module, REMOVE it, throw it away. They leak to earth, and kill the system in a heartbeat.
Thats enough for now, lets know how you go. These systems are SIMPLE, but you must be thorough and systematic with it.
Last edited by Grant Francis; 03-22-2016 at 05:43 PM.
#3
03-22-2016, 08:17 PM
Welcome first and foremost. Please do an intro in the "New Members Area" when time permits.
No idea of your area, as you do not mention it, and some markets do vary with stuff, but the basics of the V12 are:
The fuel and ignition systems are TOTALLY seperate. The ECU in the boot is for fuel only. The "Black Box" on the LH inlet manifold is for spark/tacho.
BUT, and there is always a BUT. There is a shielded wire that runs from that amp to Pin 18 of the ECU, and that supplies a pulse signal to the ECU to inform it that there is ignition activity and its time to wake up the injectors etc.
Second BUT, that wire is by-passed during cranking so the ECU does its fuel thing for initial starting, but as soon as cranking ceases that shielded wire is the only communication for continual running, and that wire BREAKS.
You have 2 ign coils, one in the V, one out the front on the LH side in front of the radiator. They fail, surprised? There is an upgrade to a single coil system, but for now ensure both coiuls are reading 1.2ohms across the +ve and -ver terminals, (or thereabouts) with NOTHING connected to them.
The coil in the V has a 12v IGN feed wire attached, make sure you got 12v IGN to the +ve of that coil, AND, that the 12v remains whilst cranking is happening, coz the Ignition Switch electrical section can drop signal due to old age.
Then, remove the coil HT lead from the cap, and crank it, and observe spark OUT of the coil as the first step. If ya got that, goodo. Then check the easiest HT lead AT the spark plug. If that is a no-go, remove the cap, CAREFULLY, and check the carbon brush at the centre post, they do go AWOL at times.
NEXT.
Inside that amp is a module, GM unit, and they can be flaky at times, BUT, here we go again, you will notice a "condensor" looking cylinder tucked in the corner, with a lead to one of the +ver terminals of that module, REMOVE it, throw it away. They leak to earth, and kill the system in a heartbeat.
Thats enough for now, lets know how you go. These systems are SIMPLE, but you must be thorough and systematic with it.
No idea of your area, as you do not mention it, and some markets do vary with stuff, but the basics of the V12 are:
The fuel and ignition systems are TOTALLY seperate. The ECU in the boot is for fuel only. The "Black Box" on the LH inlet manifold is for spark/tacho.
BUT, and there is always a BUT. There is a shielded wire that runs from that amp to Pin 18 of the ECU, and that supplies a pulse signal to the ECU to inform it that there is ignition activity and its time to wake up the injectors etc.
Second BUT, that wire is by-passed during cranking so the ECU does its fuel thing for initial starting, but as soon as cranking ceases that shielded wire is the only communication for continual running, and that wire BREAKS.
You have 2 ign coils, one in the V, one out the front on the LH side in front of the radiator. They fail, surprised? There is an upgrade to a single coil system, but for now ensure both coiuls are reading 1.2ohms across the +ve and -ver terminals, (or thereabouts) with NOTHING connected to them.
The coil in the V has a 12v IGN feed wire attached, make sure you got 12v IGN to the +ve of that coil, AND, that the 12v remains whilst cranking is happening, coz the Ignition Switch electrical section can drop signal due to old age.
Then, remove the coil HT lead from the cap, and crank it, and observe spark OUT of the coil as the first step. If ya got that, goodo. Then check the easiest HT lead AT the spark plug. If that is a no-go, remove the cap, CAREFULLY, and check the carbon brush at the centre post, they do go AWOL at times.
NEXT.
Inside that amp is a module, GM unit, and they can be flaky at times, BUT, here we go again, you will notice a "condensor" looking cylinder tucked in the corner, with a lead to one of the +ver terminals of that module, REMOVE it, throw it away. They leak to earth, and kill the system in a heartbeat.
Thats enough for now, lets know how you go. These systems are SIMPLE, but you must be thorough and systematic with it.
#4
03-22-2016, 10:03 PM
OK.
Open that amp and remove that condensor thingy for starters.
Next ensure you have 12v at the +ve of the primary coil with ign ON, and then check that you still have somewhere around 12v whilst cranking. That will eliminate the ign switch somewhat.
Next check that the patch lead between the 2 coils is wired +ve to +ve, and -ve to -ve.
I realise you have replaced the 2 coils, with what??, and what primary ohms are they reading?
Concentrate on HT spark out of the primary coil for starters. Once you get the Fat Blue Crack down that lead, the rest is simple. HT leads on these suffer badly with the heat, so use a known good lead in the coil for now.
That weak spark you got with teh Hot Wire indicates the system is basically doing its thing, but something is haywire.
Just to humour the Old Guy (me), carefully look at the earth strap fiasco around the LH engine mount. It is dumb at best, and they do fail, get very high resistance, etc, and all sorts of electrical havoc appears. I run a dedicated earth lead from the engine to the body/chassis.
Once you come back with the systematic recheck I will continue with it.
Where are you located???????, coz some markets have different engine specs.
Open that amp and remove that condensor thingy for starters.
Next ensure you have 12v at the +ve of the primary coil with ign ON, and then check that you still have somewhere around 12v whilst cranking. That will eliminate the ign switch somewhat.
Next check that the patch lead between the 2 coils is wired +ve to +ve, and -ve to -ve.
I realise you have replaced the 2 coils, with what??, and what primary ohms are they reading?
Concentrate on HT spark out of the primary coil for starters. Once you get the Fat Blue Crack down that lead, the rest is simple. HT leads on these suffer badly with the heat, so use a known good lead in the coil for now.
That weak spark you got with teh Hot Wire indicates the system is basically doing its thing, but something is haywire.
Just to humour the Old Guy (me), carefully look at the earth strap fiasco around the LH engine mount. It is dumb at best, and they do fail, get very high resistance, etc, and all sorts of electrical havoc appears. I run a dedicated earth lead from the engine to the body/chassis.
Once you come back with the systematic recheck I will continue with it.
Where are you located???????, coz some markets have different engine specs.
#5
03-22-2016, 11:33 PM
OK.
Open that amp and remove that condensor thingy for starters.
Next ensure you have 12v at the +ve of the primary coil with ign ON, and then check that you still have somewhere around 12v whilst cranking. That will eliminate the ign switch somewhat.
Next check that the patch lead between the 2 coils is wired +ve to +ve, and -ve to -ve.
I realise you have replaced the 2 coils, with what??, and what primary ohms are they reading?
Concentrate on HT spark out of the primary coil for starters. Once you get the Fat Blue Crack down that lead, the rest is simple. HT leads on these suffer badly with the heat, so use a known good lead in the coil for now.
That weak spark you got with teh Hot Wire indicates the system is basically doing its thing, but something is haywire.
Just to humour the Old Guy (me), carefully look at the earth strap fiasco around the LH engine mount. It is dumb at best, and they do fail, get very high resistance, etc, and all sorts of electrical havoc appears. I run a dedicated earth lead from the engine to the body/chassis.
Once you come back with the systematic recheck I will continue with it.
Where are you located???????, coz some markets have different engine specs.
Open that amp and remove that condensor thingy for starters.
Next ensure you have 12v at the +ve of the primary coil with ign ON, and then check that you still have somewhere around 12v whilst cranking. That will eliminate the ign switch somewhat.
Next check that the patch lead between the 2 coils is wired +ve to +ve, and -ve to -ve.
I realise you have replaced the 2 coils, with what??, and what primary ohms are they reading?
Concentrate on HT spark out of the primary coil for starters. Once you get the Fat Blue Crack down that lead, the rest is simple. HT leads on these suffer badly with the heat, so use a known good lead in the coil for now.
That weak spark you got with teh Hot Wire indicates the system is basically doing its thing, but something is haywire.
Just to humour the Old Guy (me), carefully look at the earth strap fiasco around the LH engine mount. It is dumb at best, and they do fail, get very high resistance, etc, and all sorts of electrical havoc appears. I run a dedicated earth lead from the engine to the body/chassis.
Once you come back with the systematic recheck I will continue with it.
Where are you located???????, coz some markets have different engine specs.
The following users liked this post:
Grant Francis (03-23-2016)
#6
03-23-2016, 01:26 PM
OK.
Open that amp and remove that condensor thingy for starters.
Next ensure you have 12v at the +ve of the primary coil with ign ON, and then check that you still have somewhere around 12v whilst cranking. That will eliminate the ign switch somewhat.
Next check that the patch lead between the 2 coils is wired +ve to +ve, and -ve to -ve.
I realise you have replaced the 2 coils, with what??, and what primary ohms are they reading?
Concentrate on HT spark out of the primary coil for starters. Once you get the Fat Blue Crack down that lead, the rest is simple. HT leads on these suffer badly with the heat, so use a known good lead in the coil for now.
That weak spark you got with teh Hot Wire indicates the system is basically doing its thing, but something is haywire.
Just to humour the Old Guy (me), carefully look at the earth strap fiasco around the LH engine mount. It is dumb at best, and they do fail, get very high resistance, etc, and all sorts of electrical havoc appears. I run a dedicated earth lead from the engine to the body/chassis.
Once you come back with the systematic recheck I will continue with it.
Where are you located???????, coz some markets have different engine specs.
Open that amp and remove that condensor thingy for starters.
Next ensure you have 12v at the +ve of the primary coil with ign ON, and then check that you still have somewhere around 12v whilst cranking. That will eliminate the ign switch somewhat.
Next check that the patch lead between the 2 coils is wired +ve to +ve, and -ve to -ve.
I realise you have replaced the 2 coils, with what??, and what primary ohms are they reading?
Concentrate on HT spark out of the primary coil for starters. Once you get the Fat Blue Crack down that lead, the rest is simple. HT leads on these suffer badly with the heat, so use a known good lead in the coil for now.
That weak spark you got with teh Hot Wire indicates the system is basically doing its thing, but something is haywire.
Just to humour the Old Guy (me), carefully look at the earth strap fiasco around the LH engine mount. It is dumb at best, and they do fail, get very high resistance, etc, and all sorts of electrical havoc appears. I run a dedicated earth lead from the engine to the body/chassis.
Once you come back with the systematic recheck I will continue with it.
Where are you located???????, coz some markets have different engine specs.
Last edited by Greeps; 03-23-2016 at 01:54 PM.
#7
03-23-2016, 02:38 PM
Ground strap looks good. Ohms on the pick up coil is at 3.2ish. Primary ignition coil is sending out 2.5 (flamethrower), aux is sending out 1.5 and the old primary ignition coil is not showing anything. Got another primary ignition coil coming in today. Took the condenser out of the amplifier. Getting 11.8v to the primary ignition coil. Ran a dedicated ground so I don't think it's a ground issue but this is the first jag I've worked on so it's a big learning process.
Trending Topics
#8
03-23-2016, 06:21 PM
Also check the 2 +ve battery posts on the firewall. They are somewhat hidden.
The battery cable in the boot travels under the car to the LH post, then a buzz cable travels across the rear of the engine to the RH post, then down to the starter solenoid.
On our RHD cars the LH is close to the heater pipe outlets in the firewall, and the RH is below, and towards the engine slightly of the brake booster mounting bracket.
These are KNOWN voltage drop points. Dismantle and CLEAN and GREASE these. Dont drop those nuts as they are a unique oddball thread.
Being LHD your starter motor is WAY easier to access than ours, sooooo, check the nut on TOP of the solenoid where that battery cable from the RH post attaches.
That drop is also indicative of engine earth strap issues as I mentioned before. Go get a battery cable with eye to eye ends, and attach it somewhere from the engine direct to the chassis. There are plenty of spots when under the car for this. Temporarily attach a jumper cable from the engine to the chassis earth and check that voltage again, maybe that simple.
Remember this engine is rubber mounted to the cradle, then the cradle is rubber mounted to the chassis, so the Jagaur earth straps go engine to cradle, then cradle to chassis, AT the LH engine mount. Then they put a power steer cooler, which always leaks, in the same area, so the straps get contaminated over the years. Every V12 I have worked on over the many years has had earth strap issues of some sort.
The battery cable in the boot travels under the car to the LH post, then a buzz cable travels across the rear of the engine to the RH post, then down to the starter solenoid.
On our RHD cars the LH is close to the heater pipe outlets in the firewall, and the RH is below, and towards the engine slightly of the brake booster mounting bracket.
These are KNOWN voltage drop points. Dismantle and CLEAN and GREASE these. Dont drop those nuts as they are a unique oddball thread.
Being LHD your starter motor is WAY easier to access than ours, sooooo, check the nut on TOP of the solenoid where that battery cable from the RH post attaches.
That drop is also indicative of engine earth strap issues as I mentioned before. Go get a battery cable with eye to eye ends, and attach it somewhere from the engine direct to the chassis. There are plenty of spots when under the car for this. Temporarily attach a jumper cable from the engine to the chassis earth and check that voltage again, maybe that simple.
Remember this engine is rubber mounted to the cradle, then the cradle is rubber mounted to the chassis, so the Jagaur earth straps go engine to cradle, then cradle to chassis, AT the LH engine mount. Then they put a power steer cooler, which always leaks, in the same area, so the straps get contaminated over the years. Every V12 I have worked on over the many years has had earth strap issues of some sort.
Last edited by Grant Francis; 03-23-2016 at 06:24 PM.
The following users liked this post:
Greg in France (03-24-2016)
#9
03-24-2016, 02:33 AM
Veteran Member
For those who love trivia, the firewall positive post has a Whitworth thread! Why I have no idea, but basically Whitworth was the first person (I believe) to codify threads, a very gifted pioneering Victorian era engineer, 19th century, and the first person to measure anything to an accuracy of 1,000,000th of an inch. Whitworth threads stopped being used on cars in the 1950s, so why it is on those posts I have no idea! My 1950s Massey Ferguson tractor has them though!
Greg
Greg
The following users liked this post:
Grant Francis (03-24-2016)
#10
03-24-2016, 05:01 AM
Thread
Thread Starter
Forum
Replies
Last Post
Johnken
XK8 / XKR ( X100 )
8
03-23-2016 10:56 AM
FastCat85
PRIVATE For Sale / Trade or Buy Classifieds
0
03-22-2016 10:39 AM
FastCat85
PRIVATE For Sale / Trade or Buy Classifieds
0
03-22-2016 10:27 AM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)