Ditching the plug extenders
Discussion
I don’t know the detail. All I know is watching the Tuscan Challenge qualifying a couple of years ago, I noticed that one car totally buggered the PA system every time it came past the pits. It ground to a halt a couple of laps later. Made my way back to the pits, to find Mat Smith and a couple of other drivers looking at it puzzled. I told Mat about the PA interference, he whipped a plug out and sent the pit crew off to Halfords for a set of resistive plugs. It sorted it, but I think either the ECU or coil was damaged by it. Cannot remember which.
Edited by QBee on Tuesday 4th September 20:39
I thought it was as it can cause interference re ECU but only because I read it on here. When my MBE went in and plug extenders removed I didn’t have resistive plugs put in that I remember and it didn’t cause a problem,, I then went to Iridium resistive based on what others said. Maybe modern Ecu are not effected or its a load of tat! I never used the radio but in the old days that’s what I thought they were for as you say 
NGK "R" or resistor spark plugs use a 5k ohm ceramic resistor in the spark plug to suppress ignition noise generated during sparking. And of course these days there's more to it than just radio interference, for example it's important to use resistor spark plugs in any vehicle that uses on-board computer systems to monitor or control engine performance (an ECU), this is because resistor spark plugs help to reduce electromagnetic interference (EMI).
In fact, using a non-resistor plug in certain applications can actually cause the engine to suffer undesirable side effects such as an erratic idle, high-rpm misfire, engine run-on, power drop off at certain rpm levels and abnormal combustion. EMI can be a real problem on some after market stand alone engine management systems, if the ECU isn't properly shielded control systems managed by the ECU can be servery affected.
For example a PWM idle air control valve is a typical victim of excessive EMI and as we know TVRs are especially vulnerable to earthing issues, the result of this can be earth loops. An earth loop is an unwanted electric current path in a circuit resulting in stray signals or interference, occurring for example when two earthed points in the same circuit have different potentials. To help all sensors should be 'Star Earthed' which simply means all sensors should be earthed to the same single point on the engine block, this eliminates or at least dramatically decreases the chance of there being a potential difference in a circuit or circuits so reducing the chance of earth loops that play havoc with ECU behavior and performance.
The above is well understood by the engine management industry, as such there's a universal standard for shielding that was developed in France many years ago, all ECUs must meet this standard if they are to be type approved. Basically the ECU is placed in a chamber and bombarded with EMI, it's ability to cope is measured against a standard that must be met or it will not be awarded the type approval.
MBE Systems quote their clients as being Harley Davidson, Honda UK & Europe, Nissan UK, Sikorsky Aircraft, Mitsubishi Motors UK, Morgan, Caterham, Cosworth ect ect ect ect.... as such I would have thought their ECU's must have been type approved which means they will have passed the very strict industry standards for tolerance to EMI..... amongst many other critical tests an OEM ECU must pass before it can be classed as type approved.
It also seems MBE have a great deal of experience producing engine management systems for fiberglass bodied vehicles such as Caterham, TVR, Farbio, Nobel ect ect. A type approved MBE system is therefore a safe choice for people looking for an OEM standard engine management system for their fiberglass bodied TVR.
Other engine managements systems may work well when installed on say a Range Rover which has an aluminum body, but suffer issues when fitted to a TVR, this is because the metal body of the Range Rover acts as a giant ground plane which in simple terms is an electrically conductive surface that can be used to very effectively resolve earth loops, you simply don't have this advantage with a TVR.
Motorhomes which typically have a fiberglass body mounted to a separate steel chassis suffer a lot from earth loops, in its construction if you think about it a motorhome is effectively a giant TVR. The way the motorhome industry solves the problem is to set a a large flat metal plate into the roof of the vehicle to create a nice big earth plane, a TVR would really benefit from the same but obviously this isn't as easy to install on a TVR.
As we all know TVRs nearly always suffer poor radio reception, this could have also been averted if a ground plane was used, what TVR should have done is what the motorhome industry have learnt to do, they should have set a large flat conductive metal plate into one of the two large flat panels on the car (the bonnet or boot lid) and earthed the problematic circuits and devices such as the radio to it. Just as the motorhome industry has shown us this would have instantly solved the radio interference issues and made the engine management system more stable too.
Fortunately for TVR the 14CUX ECU was properly designed with EMI in mind so it's very tolerant (but not immune in a TVR) to these issues, ECUs from this period were always encased in a metal box for good reason, although these days if correctly shielded a plastic enclosure can work acceptably too.
I've had a number of Canems ECUs over the years for reasons that do not relate to EMI, but not all have been created equal in relation to the super important element of shielding, most have shown good resistance to EMI but one clearly had issues in this respect. I was told the ECU has no such issues on a Range Rover but clearly as already explained fitting an ECU to a Range Rover with it's large flat metal panels which make for an ideal ground plane is a very different situation to fitting the same ECU to a fiberglass bodied vehicle that has no such advantage.
I was told the issue was that the ECU manufacturer shouldn't have advised me to earth the braided shielding on the crank position wire to the battery which is correct, but the reality was when correctly earthed the issues were not completely eliminated. I was told the problem was my electric water pump so this was disconnected but the problem persisted, I was then told the problem was the idle valve which is comical really as this is an integral component to the Canems installation itself.
The truth is it's quite clear we can't just keep blaming individual electric components for generating EMI and causing the issues, we have to accept the fundamental source of the issue is the ECU in question was not correctly shielded like my previous incarnations of this ECU clearly were. For instance if I connect my five year old petrol only Canems ECU all the EMI issues vanish, I then connect the far more recent ECU and the issues immediately return. Nothing else has changed, the electric water pump and idle valve are still connected, it's just one ECU is clearly better shielded than the other, it doesn't takes a genius to join the dots and conclude something relating shielding was left out by accident and really needs reinstating.
This issue of consistency is common with hand built electronics, components like heat pads can be left out by mistake as has happened in the past leading to another failure proving errors in production have been made in the past. In the world of electronics true repeatable reliability and consistent performance can only come from from productionisation, because hand assembly is far more open to human error.
As a loyal customer and committed advocate of the system I remain very open to being contacted by the manufacturer to resolve the shielding issue my latest ECU is quite clearly exhibiting, and we need to move on from blaming the customer or the various electrical components for producing EMI. All I really need is an ECU that offers the same level of shielding as all my other Canems ECUs have offered, which probably just means adding a circuit or component that was mistakenly omitted when my current Canems ECU was built.
In fact, using a non-resistor plug in certain applications can actually cause the engine to suffer undesirable side effects such as an erratic idle, high-rpm misfire, engine run-on, power drop off at certain rpm levels and abnormal combustion. EMI can be a real problem on some after market stand alone engine management systems, if the ECU isn't properly shielded control systems managed by the ECU can be servery affected.
For example a PWM idle air control valve is a typical victim of excessive EMI and as we know TVRs are especially vulnerable to earthing issues, the result of this can be earth loops. An earth loop is an unwanted electric current path in a circuit resulting in stray signals or interference, occurring for example when two earthed points in the same circuit have different potentials. To help all sensors should be 'Star Earthed' which simply means all sensors should be earthed to the same single point on the engine block, this eliminates or at least dramatically decreases the chance of there being a potential difference in a circuit or circuits so reducing the chance of earth loops that play havoc with ECU behavior and performance.
The above is well understood by the engine management industry, as such there's a universal standard for shielding that was developed in France many years ago, all ECUs must meet this standard if they are to be type approved. Basically the ECU is placed in a chamber and bombarded with EMI, it's ability to cope is measured against a standard that must be met or it will not be awarded the type approval.
MBE Systems quote their clients as being Harley Davidson, Honda UK & Europe, Nissan UK, Sikorsky Aircraft, Mitsubishi Motors UK, Morgan, Caterham, Cosworth ect ect ect ect.... as such I would have thought their ECU's must have been type approved which means they will have passed the very strict industry standards for tolerance to EMI..... amongst many other critical tests an OEM ECU must pass before it can be classed as type approved.
It also seems MBE have a great deal of experience producing engine management systems for fiberglass bodied vehicles such as Caterham, TVR, Farbio, Nobel ect ect. A type approved MBE system is therefore a safe choice for people looking for an OEM standard engine management system for their fiberglass bodied TVR.
Other engine managements systems may work well when installed on say a Range Rover which has an aluminum body, but suffer issues when fitted to a TVR, this is because the metal body of the Range Rover acts as a giant ground plane which in simple terms is an electrically conductive surface that can be used to very effectively resolve earth loops, you simply don't have this advantage with a TVR.
Motorhomes which typically have a fiberglass body mounted to a separate steel chassis suffer a lot from earth loops, in its construction if you think about it a motorhome is effectively a giant TVR. The way the motorhome industry solves the problem is to set a a large flat metal plate into the roof of the vehicle to create a nice big earth plane, a TVR would really benefit from the same but obviously this isn't as easy to install on a TVR.
As we all know TVRs nearly always suffer poor radio reception, this could have also been averted if a ground plane was used, what TVR should have done is what the motorhome industry have learnt to do, they should have set a large flat conductive metal plate into one of the two large flat panels on the car (the bonnet or boot lid) and earthed the problematic circuits and devices such as the radio to it. Just as the motorhome industry has shown us this would have instantly solved the radio interference issues and made the engine management system more stable too.
Fortunately for TVR the 14CUX ECU was properly designed with EMI in mind so it's very tolerant (but not immune in a TVR) to these issues, ECUs from this period were always encased in a metal box for good reason, although these days if correctly shielded a plastic enclosure can work acceptably too.
I've had a number of Canems ECUs over the years for reasons that do not relate to EMI, but not all have been created equal in relation to the super important element of shielding, most have shown good resistance to EMI but one clearly had issues in this respect. I was told the ECU has no such issues on a Range Rover but clearly as already explained fitting an ECU to a Range Rover with it's large flat metal panels which make for an ideal ground plane is a very different situation to fitting the same ECU to a fiberglass bodied vehicle that has no such advantage.
I was told the issue was that the ECU manufacturer shouldn't have advised me to earth the braided shielding on the crank position wire to the battery which is correct, but the reality was when correctly earthed the issues were not completely eliminated. I was told the problem was my electric water pump so this was disconnected but the problem persisted, I was then told the problem was the idle valve which is comical really as this is an integral component to the Canems installation itself.
The truth is it's quite clear we can't just keep blaming individual electric components for generating EMI and causing the issues, we have to accept the fundamental source of the issue is the ECU in question was not correctly shielded like my previous incarnations of this ECU clearly were. For instance if I connect my five year old petrol only Canems ECU all the EMI issues vanish, I then connect the far more recent ECU and the issues immediately return. Nothing else has changed, the electric water pump and idle valve are still connected, it's just one ECU is clearly better shielded than the other, it doesn't takes a genius to join the dots and conclude something relating shielding was left out by accident and really needs reinstating.
This issue of consistency is common with hand built electronics, components like heat pads can be left out by mistake as has happened in the past leading to another failure proving errors in production have been made in the past. In the world of electronics true repeatable reliability and consistent performance can only come from from productionisation, because hand assembly is far more open to human error.
As a loyal customer and committed advocate of the system I remain very open to being contacted by the manufacturer to resolve the shielding issue my latest ECU is quite clearly exhibiting, and we need to move on from blaming the customer or the various electrical components for producing EMI. All I really need is an ECU that offers the same level of shielding as all my other Canems ECUs have offered, which probably just means adding a circuit or component that was mistakenly omitted when my current Canems ECU was built.
I ditched the extenders & trialled using thermal socks. Significantly improved running but the rubber plug caps burned through quickly as might be expected.
My permanent solution was a ceramic lead set (actually ceramic plug caps). The make/type to use are "Accel 9002C Ceramic Leads". These are a 135 degree plug cap universal lead set that you make up to length at the dizzy end, They come with a king lead, crimp anvils & dielectric grease to aid assembly & plug cap removal.
I did a bit of homework and ended up buying from one of the USA speed shops on eBay using the eBay Global Shipping Program.
My permanent solution was a ceramic lead set (actually ceramic plug caps). The make/type to use are "Accel 9002C Ceramic Leads". These are a 135 degree plug cap universal lead set that you make up to length at the dizzy end, They come with a king lead, crimp anvils & dielectric grease to aid assembly & plug cap removal.
I did a bit of homework and ended up buying from one of the USA speed shops on eBay using the eBay Global Shipping Program.
I think I remember from another thread that you disconnected your idle valve for many reasons but one was that it was causing the ecu to reset in a on-off loop? Do you have a diode fitted across the idle valve supply wires ? I don't know much about the 2 wire IACVs because I don't use them, but it seems logical that as it's basically a wirewound magnetic field then there will be a back emf every time the PWM switches to off .. presumably the diode is there to prevent that reaching the ecu. Maybe it's causing other issues too which are similarly symptomatic of an EMI issue.
Just a thought.
Just a thought.
Thanks, no diode, well not that I'm aware of.
Lets study the facts!
The idle valve causes the priming pulse to loop, my little electric water pump causes the priming pulse to loop, if I turn my ignition back on when the engine is hot and the rad fans chime in they also cause the priming pulse to loop.
With so many different electrical componets causing the priming pulse to loop I conclude the components aren't my issue, the real issue resides inside my latest Canems ECU or more specifically something's that was left out.
The final proof that delivers all the evidence anyone with a logical mind would need to make their final diagnosis is provided by the fact when I plug in my spare petrol only ECU there's none of all this looping priming pulse business, which was meant to be corrected by relocating the crank signal wire's braided shielding.
Good job I didnt back down and I refused to pay the quoted £500 for that work, because just as I suspected all along the way the crank signal wire was earthed wasn't ever the issue even though I was advised by Canems to earth to the battery which is clearly not best practice.
If it looks like an ECU fault, and smells like an ECU fault.... no ship Sherlock it probably is an ECU fault!
Its such a shame, because in every other respect the Canems dual fuel ECU is an outstanding creation! All I need is an offer to correct the fault, what I don't need is to be made to feel like its in some way my own fault.
I've had good support in the past, and I've tested this support extensively, the repeated failures have seen to that. But I'm tiered now, I've run out of patience and my good will is slipping away. It's become all too much hard work and effort to remain the eternal optimist so I'm investing my last drops of optimism in the hope the people who can and should sort my problem out may read this.
Lets study the facts!
The idle valve causes the priming pulse to loop, my little electric water pump causes the priming pulse to loop, if I turn my ignition back on when the engine is hot and the rad fans chime in they also cause the priming pulse to loop.
With so many different electrical componets causing the priming pulse to loop I conclude the components aren't my issue, the real issue resides inside my latest Canems ECU or more specifically something's that was left out.
The final proof that delivers all the evidence anyone with a logical mind would need to make their final diagnosis is provided by the fact when I plug in my spare petrol only ECU there's none of all this looping priming pulse business, which was meant to be corrected by relocating the crank signal wire's braided shielding.
Good job I didnt back down and I refused to pay the quoted £500 for that work, because just as I suspected all along the way the crank signal wire was earthed wasn't ever the issue even though I was advised by Canems to earth to the battery which is clearly not best practice.
If it looks like an ECU fault, and smells like an ECU fault.... no ship Sherlock it probably is an ECU fault!
Its such a shame, because in every other respect the Canems dual fuel ECU is an outstanding creation! All I need is an offer to correct the fault, what I don't need is to be made to feel like its in some way my own fault.
I've had good support in the past, and I've tested this support extensively, the repeated failures have seen to that. But I'm tiered now, I've run out of patience and my good will is slipping away. It's become all too much hard work and effort to remain the eternal optimist so I'm investing my last drops of optimism in the hope the people who can and should sort my problem out may read this.
Edited by ChimpOnGas on Wednesday 5th September 20:01
How is your crank sense wire earthed at the moment? It's supposed to be earthed at one end only.
So the priming pulse is a once only key-on event, but your ecu keeps sending a signal to the fuel pump relay over and over.
Can you see the rpm number change whilst this is happening? If so it's picking up interference on the crank input. If not it's something else.
What happens to the ecu voltage when it's looping? Is the ecu threshold voltage too high, so a drop of voltage down to say 10v is enough to trigger a key-off state in the ecu, then the ecu cuts the earthing to the pump relay, the load on the pump diminishes, the ecu voltage goes back up, the ecu thinks you've keyed on again and earths the fuel pump relay, which lowers the voltage at the ecu, the ecu thinks you've keyed off, cuts the earth to the fuel pump relay, the load from the pump diminishes, the ecu voltage goes back up, the ecu thinks you've keyed on again, energises the fuel pump ad infinitum ...
I'm sure you will have datalogged the looping .. what actually does it tell you?
What happens if you take out the fuel pump relay and connect a test bulb to the ecu earth pin for the relay? Does the test bulb flash on and off or does it flash on for priming and then stay off at the end of the correct ecu priming time? If it stays off at the end of the correct priming pulse length of time then you might consider a flyback diode in the fuel pump relay (many relays have these in anyway so would be good to fit one of those?).
Have you tried running the ecu from a battery which is separate from the car? IE isolate the ecu power supply from that of the cars own battery.
I recently went through a similar diagnostic process with a car whose IACV reset itself when the starter was energised .. turned out that there was a poor earth on the engine (the ecu was earthed to the engine block) and there was a voltage rise at the ecu earth which was enough to cause the ecu to think the ecu had been powered down for a split second, so the ecu reset the IACV (which on this car was set to re-sync at ecu power on)
It's a shame you don't apear to be getting full support in tracing this though. If an updated version of firmware/hardware created this situation and the powers that be don't want to get involved any more with trying to suss it all out I'd be tempted to go back to the last stable version of ecu and leave it at that. Until it's fixed then presumably the latest version of your ecu cannot be used in dual fuel mode in other tvrs? Or if it IS just the fact that something was left out / whatever in your particular build then I don't understand why that can't be easily fixed, or just give you another brand new ecu. Sometimes in business you just have to give something new to sort it all out even though it's costly to the supplier/fitter .. the goodwill cannot be valued highly enough.
So the priming pulse is a once only key-on event, but your ecu keeps sending a signal to the fuel pump relay over and over.
Can you see the rpm number change whilst this is happening? If so it's picking up interference on the crank input. If not it's something else.
What happens to the ecu voltage when it's looping? Is the ecu threshold voltage too high, so a drop of voltage down to say 10v is enough to trigger a key-off state in the ecu, then the ecu cuts the earthing to the pump relay, the load on the pump diminishes, the ecu voltage goes back up, the ecu thinks you've keyed on again and earths the fuel pump relay, which lowers the voltage at the ecu, the ecu thinks you've keyed off, cuts the earth to the fuel pump relay, the load from the pump diminishes, the ecu voltage goes back up, the ecu thinks you've keyed on again, energises the fuel pump ad infinitum ...
I'm sure you will have datalogged the looping .. what actually does it tell you?
What happens if you take out the fuel pump relay and connect a test bulb to the ecu earth pin for the relay? Does the test bulb flash on and off or does it flash on for priming and then stay off at the end of the correct ecu priming time? If it stays off at the end of the correct priming pulse length of time then you might consider a flyback diode in the fuel pump relay (many relays have these in anyway so would be good to fit one of those?).
Have you tried running the ecu from a battery which is separate from the car? IE isolate the ecu power supply from that of the cars own battery.
I recently went through a similar diagnostic process with a car whose IACV reset itself when the starter was energised .. turned out that there was a poor earth on the engine (the ecu was earthed to the engine block) and there was a voltage rise at the ecu earth which was enough to cause the ecu to think the ecu had been powered down for a split second, so the ecu reset the IACV (which on this car was set to re-sync at ecu power on)
It's a shame you don't apear to be getting full support in tracing this though. If an updated version of firmware/hardware created this situation and the powers that be don't want to get involved any more with trying to suss it all out I'd be tempted to go back to the last stable version of ecu and leave it at that. Until it's fixed then presumably the latest version of your ecu cannot be used in dual fuel mode in other tvrs? Or if it IS just the fact that something was left out / whatever in your particular build then I don't understand why that can't be easily fixed, or just give you another brand new ecu. Sometimes in business you just have to give something new to sort it all out even though it's costly to the supplier/fitter .. the goodwill cannot be valued highly enough.
Edited by spitfire4v8 on Thursday 6th September 10:06
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