Does the ECU need to be matched to the ignition system?
Does the ECU need to be matched to the ignition system?
Hi Everyone,
My Series 3 XJ6 85 is playing games with me.
Fuel system has been totally overhauled. (Feul pump, Injectors, Fuel Reg, etc.)
Dissy tests OK
Earth wires have been checked
Wiring is good for a 30 year old car - Everything is tight, clean and shielded.
In desperation I have just fitted new Lucas Ignition Amplifier AB14
Starts from cold a treat.
BUT, when it is hot, it won't start.
Cranks over, but won't fire.
I have spark at the coil and pulse in the injectors from periodic testing.
Open bonnet and the coil is burning hot.
Swapped it out for a Bosch GT40 yesterday.
It lasted 1 1/2 hours before the car actually stalled in traffic and wouldn't start at all.
Luckily, I had the old coil in the boot, so swapped it back in to limp home.
Today, fitted a 2nd hand Lucas HEI series 3 xj6 spec coil
An hour later, no start, coil boiling hot.
Cold water on a rag onto the coil to cool it AND start engine with accelerator to the floor gets it going, and it is fine until I shut the engine down again!
What am I missing?
When I first bought the car a couple of months ago, I swapped the ECU out trying to diagnose another problem. Did I create this one?
Does the ECU need to be matched with the ignition system
My car does not have a ballast resistor, but I have seen other Series 3's of a similar age with a ballast resistor fitted, so is their ECU different and did I swap in an incorrect ECU?
Any advice or your thoughts would be appreciated.
Cheers,
Nigel
My Series 3 XJ6 85 is playing games with me.
Fuel system has been totally overhauled. (Feul pump, Injectors, Fuel Reg, etc.)
Dissy tests OK
Earth wires have been checked
Wiring is good for a 30 year old car - Everything is tight, clean and shielded.
In desperation I have just fitted new Lucas Ignition Amplifier AB14
Starts from cold a treat.
BUT, when it is hot, it won't start.
Cranks over, but won't fire.
I have spark at the coil and pulse in the injectors from periodic testing.
Open bonnet and the coil is burning hot.
Swapped it out for a Bosch GT40 yesterday.
It lasted 1 1/2 hours before the car actually stalled in traffic and wouldn't start at all.
Luckily, I had the old coil in the boot, so swapped it back in to limp home.
Today, fitted a 2nd hand Lucas HEI series 3 xj6 spec coil
An hour later, no start, coil boiling hot.
Cold water on a rag onto the coil to cool it AND start engine with accelerator to the floor gets it going, and it is fine until I shut the engine down again!
What am I missing?
When I first bought the car a couple of months ago, I swapped the ECU out trying to diagnose another problem. Did I create this one?
Does the ECU need to be matched with the ignition system
My car does not have a ballast resistor, but I have seen other Series 3's of a similar age with a ballast resistor fitted, so is their ECU different and did I swap in an incorrect ECU?
Any advice or your thoughts would be appreciated.
Cheers,
Nigel
Joined: Feb 2010
Posts: 28,803
Likes: 11,277
From: Adelaide Stralia
OK.
My dealings with the S3 6 cyl are limited, but here goes, and some V12 stuff creeps in as the AB14 is basically the same.
The HOT coil is usually a BAD module inside the amp, as it is used to control coil voltage, OR, some serious resistance in the spark plugs/leads, which will cause the coil to work VERY hard to supply spark, and if it cannot get rid of that energy (spark) it will get HOT, and eventually die.
I use a FuelMiser CC215 coil on these and the V12's, with NO issues ever. It is rated as a "Universal Electronic" ignition system coil. The GT40 is a POINTS spec coil and will reek havoc. You MUST have a coil with APPROX 0.9 ohms OR LESS across the +ve and -ve terminals (nothing connected for this test). Anything above 1.0 ohms will overheat the module and then the coil will fail very soon after.
The engine earth straps are CRITICAL here, and I am mainly referring to the big battery earth cable. If that is not 100% havoc reigns supreme.
The ECU you talk of is PURELY fuel related. Its only "communication" with the ignition system is a pulse (like a tacho pulse) that indicates the engine is running, so the fueling system remains active. Lose that pulse, dead fuel system.
Doug will slide by when the time zone align and add to this. He is THE S3 guy in my opinion.
My dealings with the S3 6 cyl are limited, but here goes, and some V12 stuff creeps in as the AB14 is basically the same.
The HOT coil is usually a BAD module inside the amp, as it is used to control coil voltage, OR, some serious resistance in the spark plugs/leads, which will cause the coil to work VERY hard to supply spark, and if it cannot get rid of that energy (spark) it will get HOT, and eventually die.
I use a FuelMiser CC215 coil on these and the V12's, with NO issues ever. It is rated as a "Universal Electronic" ignition system coil. The GT40 is a POINTS spec coil and will reek havoc. You MUST have a coil with APPROX 0.9 ohms OR LESS across the +ve and -ve terminals (nothing connected for this test). Anything above 1.0 ohms will overheat the module and then the coil will fail very soon after.
The engine earth straps are CRITICAL here, and I am mainly referring to the big battery earth cable. If that is not 100% havoc reigns supreme.
The ECU you talk of is PURELY fuel related. Its only "communication" with the ignition system is a pulse (like a tacho pulse) that indicates the engine is running, so the fueling system remains active. Lose that pulse, dead fuel system.
Doug will slide by when the time zone align and add to this. He is THE S3 guy in my opinion.
Hi Grant,
Thanks for that.
Funny, I just walked into Repco and told them what car I had.
Their system came up with GT40.
I checked the replacement Lucas HEI Coil before fitting and it had 4 ohms resistance. So much for a 'XJ6 S3 spec' coil.
The ignition Amp is brand new from Jagdaim, but I will test it.
Do you know what parameters I should be looking for?
Battery earth strap was cruddy when I first bought the car and was one of the first things attended to.
Believe it or not, now that you mention it, I haven't checked the spark plug leads.(Spark Plugs are new Bosch).
It is for this reason I posted here. There is always something that you miss. Thanks!
Where do you find FuelMiser Coils?
Cheers,
Nigel
Thanks for that.
Funny, I just walked into Repco and told them what car I had.
Their system came up with GT40.
I checked the replacement Lucas HEI Coil before fitting and it had 4 ohms resistance. So much for a 'XJ6 S3 spec' coil.
The ignition Amp is brand new from Jagdaim, but I will test it.
Do you know what parameters I should be looking for?
Battery earth strap was cruddy when I first bought the car and was one of the first things attended to.
Believe it or not, now that you mention it, I haven't checked the spark plug leads.(Spark Plugs are new Bosch).
It is for this reason I posted here. There is always something that you miss. Thanks!
Where do you find FuelMiser Coils?
Cheers,
Nigel
Joined: Feb 2010
Posts: 28,803
Likes: 11,277
From: Adelaide Stralia
Nigel,
R^%co, forget the big chains, they have NO idea, unless you know the part number of what you need.
Not sure in Melb. Maybe talk with Doug about a coil, they will have them. Maybe put CC215 into teh ?bay search. SuperCheap if you have them there may stock or have access to them. Some "Speed shops" may also have them.
My local independent/stand alone Hard Parts store always has what I want, or can get real quick.
Also check the engine earth strap from the bellhousing bolt TO the chassis, as they are often missing/loose/broken, and that is more common than most will admit.
High resistance leads are a killer on this system.
The amp is more than likely OK, as they really are more robust than many expect. The fact it is still running, sort of, does eliminate it fairly well.
The module INSIDE that amp is replaceable, and fairly easy to find, and "about" $50.
R^%co, forget the big chains, they have NO idea, unless you know the part number of what you need.
Not sure in Melb. Maybe talk with Doug about a coil, they will have them. Maybe put CC215 into teh ?bay search. SuperCheap if you have them there may stock or have access to them. Some "Speed shops" may also have them.
My local independent/stand alone Hard Parts store always has what I want, or can get real quick.
Also check the engine earth strap from the bellhousing bolt TO the chassis, as they are often missing/loose/broken, and that is more common than most will admit.
High resistance leads are a killer on this system.
The amp is more than likely OK, as they really are more robust than many expect. The fact it is still running, sort of, does eliminate it fairly well.
The module INSIDE that amp is replaceable, and fairly easy to find, and "about" $50.
Veteran Member
Joined: Jul 2012
Posts: 6,796
Likes: 2,403
From: Walnut Creek, California
Generic thoughts +:
Heat in electric components anywhere denote high resistance. Not good.
Finding it and solving it has done a lot for me over the years.
One was a lousy battery cable end. After market clamp on. Manifested in an unsolvable flat spot in acceleration!!
Carl
Heat in electric components anywhere denote high resistance. Not good.
Finding it and solving it has done a lot for me over the years.
One was a lousy battery cable end. After market clamp on. Manifested in an unsolvable flat spot in acceleration!!
Carl
Hi Grant,
I fitted a Fuel Miser cc215 earlier today, thanks for the advice.
I even got a refund from Repco for selling me the wrong coil (GT40)
Tested before fitting and showed 1.5 ohms static resistance.
It seems to be better than everything previously, however, with a limited test late this afternoon, the coil still got hot and after leaving the car parked for 20 mins , having driven it about in traffic, before trying to start it, it did hesitate to start.
In regards to spark plug leads, I didn't test them because my understanding is that if one has a problem resistance, it will manifest itself under load, ie. lack of power and or misfiring under said load, which it doesn't.
My engine doesn't misfire and it runs just as smoothly under acceleration up a hill, even now.
A bit like chess, I'm not sure what to do next.
Cheers,
Nigel
I fitted a Fuel Miser cc215 earlier today, thanks for the advice.
I even got a refund from Repco for selling me the wrong coil (GT40)
Tested before fitting and showed 1.5 ohms static resistance.
It seems to be better than everything previously, however, with a limited test late this afternoon, the coil still got hot and after leaving the car parked for 20 mins , having driven it about in traffic, before trying to start it, it did hesitate to start.
In regards to spark plug leads, I didn't test them because my understanding is that if one has a problem resistance, it will manifest itself under load, ie. lack of power and or misfiring under said load, which it doesn't.
My engine doesn't misfire and it runs just as smoothly under acceleration up a hill, even now.
A bit like chess, I'm not sure what to do next.
Cheers,
Nigel
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Joined: Feb 2010
Posts: 28,803
Likes: 11,277
From: Adelaide Stralia
OK.
That 1.5 is getting a tad high, but the module should be able to handle it.
I would be looking seriously at the leads and plugs.
I run Magnecor Spiral Wound leads on all of the Jags that run leads, and NON resistor spark plugs in these early engines. NGK BP6EY is what the XK EFI engine runs. I dont like Bosch, and I am NOT getting into a match over that brand, just my choice a very long time ago.
It still sounds like the coil cannot get rid of its energy as it should, so it builds up, and this build up is the heat you are getting. The hotter a coil gets the less efficient it is until it dies from that heat,
Very simply put, the energy "blockage" can only be the leads and/or plugs. As the leads age, the resistance goes through the roof, then add the resistor style spark plugs that most people fit, a wider plug gap than spec, and it is like a brickwall for the spark energy path. That coil has to work super hard to get thru it all, and the harder it works, the hotter it gets.
That 1.5 is getting a tad high, but the module should be able to handle it.
I would be looking seriously at the leads and plugs.
I run Magnecor Spiral Wound leads on all of the Jags that run leads, and NON resistor spark plugs in these early engines. NGK BP6EY is what the XK EFI engine runs. I dont like Bosch, and I am NOT getting into a match over that brand, just my choice a very long time ago.
It still sounds like the coil cannot get rid of its energy as it should, so it builds up, and this build up is the heat you are getting. The hotter a coil gets the less efficient it is until it dies from that heat,
Very simply put, the energy "blockage" can only be the leads and/or plugs. As the leads age, the resistance goes through the roof, then add the resistor style spark plugs that most people fit, a wider plug gap than spec, and it is like a brickwall for the spark energy path. That coil has to work super hard to get thru it all, and the harder it works, the hotter it gets.
Last edited by Grant Francis; Jun 26, 2015 at 08:23 AM.
Veteran Member
Joined: Jul 2012
Posts: 6,796
Likes: 2,403
From: Walnut Creek, California
Makes tons of sense to me. High resistance = high heat.
Options:
1. Just swap out the HT leads. especialy if aged or age unknown. Can make a word of difference.
2. Research and find an acceptable OHM per inch standard and measure yours.
3. Swab out the towers on the distributor cap. Old ones corrode markedly. Not required if hey are still bright and shiny. One of my boxes has a self made tool for this. Bent wire and a wrap of emery cloth.
Carl
Options:
1. Just swap out the HT leads. especialy if aged or age unknown. Can make a word of difference.
2. Research and find an acceptable OHM per inch standard and measure yours.
3. Swab out the towers on the distributor cap. Old ones corrode markedly. Not required if hey are still bright and shiny. One of my boxes has a self made tool for this. Bent wire and a wrap of emery cloth.
Carl
Sorry to bother everyone again
I have always fitted NGK BP5ES spark plugs, but whilst trying to fix another problem last month someone suggested Bosch WR8DC+ plugs which are currently fitted.
I lean towards Grants' thinking re NGK vs Bosch, however, I have never used NGK BP6EY plugs.
From what I understand, the number in the designation denotes spark intensity (depending on brand), or is it more correlated to resistance?
That would explain a lot in my current situation
Thanking everyone who has contributed to this thread
Cheers,
Nigel
I have always fitted NGK BP5ES spark plugs, but whilst trying to fix another problem last month someone suggested Bosch WR8DC+ plugs which are currently fitted.
I lean towards Grants' thinking re NGK vs Bosch, however, I have never used NGK BP6EY plugs.
From what I understand, the number in the designation denotes spark intensity (depending on brand), or is it more correlated to resistance?
That would explain a lot in my current situation
Thanking everyone who has contributed to this thread
Cheers,
Nigel
Joined: Feb 2010
Posts: 28,803
Likes: 11,277
From: Adelaide Stralia
Maaaaaate.
Fresh JD in hand, so multi tasking I am, and I am NOT good at it, trust me.
The "S" versus the "Y" is PURELY the centre electrode.
The "S" is for Standard, so a flat centre electrode.
The "Y" is for V Groove, and has a V in the face of the centre electrode.
The GUFF from NGK at teh time was teh OZ fule was better ignited with a series of smaller sparks from teh V goove than teh S styel, WHATEVER.
Down here, the S spec are getting very hard to find, as the Y is the current spec part number.
The 5 OR 6 is the heat range. I use either, depending on which number I remember when I go to buy them, and that is getting funnier by the day.
I was given some Bosch for the HE a very long time ago, as the Rep from Bosch was trying to convert me, and the car barely made it around the block. Refitted the OLD NGK, and power to burn. I have never seen him since that day.
Fresh JD in hand, so multi tasking I am, and I am NOT good at it, trust me.
The "S" versus the "Y" is PURELY the centre electrode.
The "S" is for Standard, so a flat centre electrode.
The "Y" is for V Groove, and has a V in the face of the centre electrode.
The GUFF from NGK at teh time was teh OZ fule was better ignited with a series of smaller sparks from teh V goove than teh S styel, WHATEVER.
Down here, the S spec are getting very hard to find, as the Y is the current spec part number.
The 5 OR 6 is the heat range. I use either, depending on which number I remember when I go to buy them, and that is getting funnier by the day.
I was given some Bosch for the HE a very long time ago, as the Rep from Bosch was trying to convert me, and the car barely made it around the block. Refitted the OLD NGK, and power to burn. I have never seen him since that day.
Drinks all round, but don't ring the Bell!
Grant,
I owe you a drink.
What's your poison..Mr Daniels!
'ES' NGK's are plentiful in Melbourne, I should send some over.
My engine has 300,000 k's on it, so I have opted for a warmer spark due to age considerations.
Just for S***'s & Giggles I tested my Spark Plug leads as I fitted my new BP5ES NGK plugs earlier today
Coil to Dissy Resistance 1.9 O
Plug 6 5.68 (longest)
Plug 5 4.80
Plug 4 4.52
Plug 3 4.61
Plug 2 3.45
Plug 1 3.46
Range isn't too bad, but I have found someone who does Magnecor leads in Melbourne, so will follow this up during the week on your advice. Thanks
I also found an NGK numeral decoding sheet which I have attached for everyone else
Salute
Nigel
I owe you a drink.
What's your poison..Mr Daniels!
'ES' NGK's are plentiful in Melbourne, I should send some over.
My engine has 300,000 k's on it, so I have opted for a warmer spark due to age considerations.
Just for S***'s & Giggles I tested my Spark Plug leads as I fitted my new BP5ES NGK plugs earlier today
Coil to Dissy Resistance 1.9 O
Plug 6 5.68 (longest)
Plug 5 4.80
Plug 4 4.52
Plug 3 4.61
Plug 2 3.45
Plug 1 3.46
Range isn't too bad, but I have found someone who does Magnecor leads in Melbourne, so will follow this up during the week on your advice. Thanks
I also found an NGK numeral decoding sheet which I have attached for everyone else
Salute
Nigel
Joined: Feb 2010
Posts: 28,803
Likes: 11,277
From: Adelaide Stralia
300000kms is JUST run in, heaps more in that XK engine yet.
Sir Arthur (in my garage) has now topped 530000kms and is untouched, and still does as it was designed to do. Had Magnecor leads since 1993, and they are still sweet.
Lets know what gives with the plugs and leads, but I reckon that should make a difference.
I prefer the Y spec plugs, and we have heaps at work, I just dont have a car to fit them to any more.
Sir Arthur (in my garage) has now topped 530000kms and is untouched, and still does as it was designed to do. Had Magnecor leads since 1993, and they are still sweet.
Lets know what gives with the plugs and leads, but I reckon that should make a difference.
I prefer the Y spec plugs, and we have heaps at work, I just dont have a car to fit them to any more.
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