New ECU for TVR Griffith help
Discussion
Have a Griff 500 with a 224 cam, Bosch injectors carbon fiber trumpets, smooth bore induction pipe, tweaked fuelling map, new leads, new coil and plugs.
Although the car does feel a bit more lively it isn’t a lot quicker on the track and is lot less agreeable to drive on the road. So my winter project is to learn about aftermarket ECUs and mapping. I know very little on the subject so lot’s of questions please advise :-
I understand that a lumpy cam at low rpm, can be helped by retarding the spark thus reducing the power produced, requiring a larger throttle opening and hence more gas flow. Is that correct ?
If it is correct, then assuming my fuel map is correct at the moment, and I devise a method of retarding the sparks at low RPM will it alter the ideal fueling. In other words can I just tweak the timing to make it less lumpy without causing damage ?
What is the benefit of individual coils (one per plug) over a Dizzy ? I guess it is a lot cheaper for the manufacturers but does assuming the coil is capable of producing the required energy and the dizzy distributes the correctly what is the benefit.
I have heard comment that the oxygen sensors struggle to produce anything other than a rich or lean output and fitting “wide band” sensors allows more progressive adjustment of the fueling. Is that true ?
How do most people get an RPM and position signal off the Rover engine ?
Although the car does feel a bit more lively it isn’t a lot quicker on the track and is lot less agreeable to drive on the road. So my winter project is to learn about aftermarket ECUs and mapping. I know very little on the subject so lot’s of questions please advise :-
I understand that a lumpy cam at low rpm, can be helped by retarding the spark thus reducing the power produced, requiring a larger throttle opening and hence more gas flow. Is that correct ?
If it is correct, then assuming my fuel map is correct at the moment, and I devise a method of retarding the sparks at low RPM will it alter the ideal fueling. In other words can I just tweak the timing to make it less lumpy without causing damage ?
What is the benefit of individual coils (one per plug) over a Dizzy ? I guess it is a lot cheaper for the manufacturers but does assuming the coil is capable of producing the required energy and the dizzy distributes the correctly what is the benefit.
I have heard comment that the oxygen sensors struggle to produce anything other than a rich or lean output and fitting “wide band” sensors allows more progressive adjustment of the fueling. Is that true ?
How do most people get an RPM and position signal off the Rover engine ?
Changing the timing won't change the mixture requirements.
Multiple coils enable you to produce a stronger spark at high RPM because the coil can be charged for longer. The existing setup is fine for a standard or mildly tuned roadgoing engine. The more highly tuned it is, the more important it will be that you get a strong consistent spark and eliminate timing jitter. This will imply getting rid of the dizzy and running multiple coils. This also gives you electronic control over the spark timing. Obviously you need an ECU capable of controlling the ignition - your existing Lucas 14CUX doesn't have that capability.
The Lambda sensors you have currently are known as narrow band sensors. They produce two signals - rich and lean - and the ECU keeps steering between these two to keep the fuelling at about lambda 1. This isn't really optimal for power, so if you're fitting a different ECU you might want to spend an extra few hundred quid and replace them with wideband sensors and the controller to manage the sensors.
You don't *have* to do any of this, by the way. You could just have your existing ECU remapped and leave everything else alone.
Multiple coils enable you to produce a stronger spark at high RPM because the coil can be charged for longer. The existing setup is fine for a standard or mildly tuned roadgoing engine. The more highly tuned it is, the more important it will be that you get a strong consistent spark and eliminate timing jitter. This will imply getting rid of the dizzy and running multiple coils. This also gives you electronic control over the spark timing. Obviously you need an ECU capable of controlling the ignition - your existing Lucas 14CUX doesn't have that capability.
The Lambda sensors you have currently are known as narrow band sensors. They produce two signals - rich and lean - and the ECU keeps steering between these two to keep the fuelling at about lambda 1. This isn't really optimal for power, so if you're fitting a different ECU you might want to spend an extra few hundred quid and replace them with wideband sensors and the controller to manage the sensors.
You don't *have* to do any of this, by the way. You could just have your existing ECU remapped and leave everything else alone.
Edited by GreenV8S on Monday 9th October 10:01
Thanks Peter, sensible reply as ever.
I have already had the Lucas unit mapped, twice, but the car is still fairly unpleasant to drive other than in “competitive” mode. My thought is to build a bit of electronics to retard the ignition at low RPM and then progressively head towards no retard at about 2000 where it starts to clean up. Looking at the overlap on the rotor arm I guess that the spark will still end up in the correct place.
If that turns out (as things often do), to be more complex that it first seems, I will buy one of the after market units. Before I start spending money though I want to understand the issues rather than just believing the “experts” as I made that mistake about this time last year.
OK about the sensors, that makes things clearer.
I have already had the Lucas unit mapped, twice, but the car is still fairly unpleasant to drive other than in “competitive” mode. My thought is to build a bit of electronics to retard the ignition at low RPM and then progressively head towards no retard at about 2000 where it starts to clean up. Looking at the overlap on the rotor arm I guess that the spark will still end up in the correct place.
If that turns out (as things often do), to be more complex that it first seems, I will buy one of the after market units. Before I start spending money though I want to understand the issues rather than just believing the “experts” as I made that mistake about this time last year.
OK about the sensors, that makes things clearer.
Hi,
I have just recently been through this with a Chim, and FWIW this is my experience;
The car had a very sporty engine, (5.0 making genuine 340hp), but the cam was very lumpy and at anything below 2k rpm was a real pain to drive, which as it was used as an everyday town car, was not ideal. It did have a very high quality ecu with all the bells and whistles and after a complete day at a rolling road with Mark A, we made it much much better, but didnt cure the problem. The cam in question was quite alot more extreme than would be fitted normally, and a fair bit wilder than a 224, the only option we found in the end was to re-spec a cam for it, which made the difference.
There are a couple of tricks that can be done with mechanical cams to change how they drive, but unfortunately not with hydraulic cams.
I think with a different control system on the engine, you may be able to change it enough, but probably not with a standard CUX ecu and mech distributor.
Let us know how it goes!
Jamie
I have just recently been through this with a Chim, and FWIW this is my experience;
The car had a very sporty engine, (5.0 making genuine 340hp), but the cam was very lumpy and at anything below 2k rpm was a real pain to drive, which as it was used as an everyday town car, was not ideal. It did have a very high quality ecu with all the bells and whistles and after a complete day at a rolling road with Mark A, we made it much much better, but didnt cure the problem. The cam in question was quite alot more extreme than would be fitted normally, and a fair bit wilder than a 224, the only option we found in the end was to re-spec a cam for it, which made the difference.
There are a couple of tricks that can be done with mechanical cams to change how they drive, but unfortunately not with hydraulic cams.
I think with a different control system on the engine, you may be able to change it enough, but probably not with a standard CUX ecu and mech distributor.
Let us know how it goes!
Jamie
Tough one..
Take a look at you cam here..
www.btinternet.com/~jon.wolfe/kentcamdata.htm
It has a lot of lift and duration .. so I would think that
cam timing set-up would be very important.
I too run a hairy cam (V8D 404 Mechanical) and when MA first mapped
it - it was not great. His second attempt was brilliant but he remapped it paying more attention to the driveability - don't know if the std RV8 system can move speed and load sites closer together but he made a good job the second time.
As someone else mentioned - the dizzy is a compramise set-up and
because of the mechanical advance retard this can scatter the spark
at higher revs. I think my dizzy causes me loads of troubles.. and it's going soon.
Something well worth you trying and it worked well on mine (and costs 10p).. disconnect the advance retard from the ignition to the
plenum. You will need to cut 2" on the lenght of rubber pipe and use 2 self tapping screws in eack of the pipe ends.
Try it - it helps the driveability.
Lastly - if you really want to go mapable - I would recommend taking a look at Emerald - I've read a lot on this site and bought Dave's book and he is great at explaining what it's all about.
And the price is not bad either.
For me one of the reasons to use this system rather than the std set-up is diagnostics - it's not running well - just get out the lap top - some things would be so obvious ..
www.emeraldm3d.com/em_m3dk.html
Take a look at you cam here..
www.btinternet.com/~jon.wolfe/kentcamdata.htm
It has a lot of lift and duration .. so I would think that
cam timing set-up would be very important.
I too run a hairy cam (V8D 404 Mechanical) and when MA first mapped
it - it was not great. His second attempt was brilliant but he remapped it paying more attention to the driveability - don't know if the std RV8 system can move speed and load sites closer together but he made a good job the second time.
As someone else mentioned - the dizzy is a compramise set-up and
because of the mechanical advance retard this can scatter the spark
at higher revs. I think my dizzy causes me loads of troubles.. and it's going soon.
Something well worth you trying and it worked well on mine (and costs 10p).. disconnect the advance retard from the ignition to the
plenum. You will need to cut 2" on the lenght of rubber pipe and use 2 self tapping screws in eack of the pipe ends.
Try it - it helps the driveability.
Lastly - if you really want to go mapable - I would recommend taking a look at Emerald - I've read a lot on this site and bought Dave's book and he is great at explaining what it's all about.
And the price is not bad either.
For me one of the reasons to use this system rather than the std set-up is diagnostics - it's not running well - just get out the lap top - some things would be so obvious ..
www.emeraldm3d.com/em_m3dk.html
Edited by rev-erend on Monday 9th October 22:46
I've been talking to Dave at Emerald recently about wasted spark emerald ecus for rover V8 so your post is a timlely one if that's one route you're thinking about... they are available 
The point Peter made about needing more spark at high cylinder pressures / rpm is a good one .. by running one coil you effectively limit it's dwell (the crank angle rotation in degrees through which the coil charges, the coil "rise time" ) .. with a single coil you are limited on that and on high compression engines turning high rpm you might not have enough energy to fire the mixture .. coil packs help there. They also eliminate timing scatter due to such things as distributor shaft wear and advance weight chatter.
Also rememebr that lambda 1 mixtures are very hard to ignite, you need a BIG spark .. and unleaded fuels ar hard to ignite but burn very fiercely once going .. so if you are catless you can run richer than lambda1 on part throttle and suffer less weak mixture misfires and also benefit from smoother combustion.
There are a lot of very good reasons for going completely mapped system.
edited to get rid of punctuation turning into smileys !!
The point Peter made about needing more spark at high cylinder pressures / rpm is a good one .. by running one coil you effectively limit it's dwell (the crank angle rotation in degrees through which the coil charges, the coil "rise time" ) .. with a single coil you are limited on that and on high compression engines turning high rpm you might not have enough energy to fire the mixture .. coil packs help there. They also eliminate timing scatter due to such things as distributor shaft wear and advance weight chatter.
Also rememebr that lambda 1 mixtures are very hard to ignite, you need a BIG spark .. and unleaded fuels ar hard to ignite but burn very fiercely once going .. so if you are catless you can run richer than lambda1 on part throttle and suffer less weak mixture misfires and also benefit from smoother combustion.
There are a lot of very good reasons for going completely mapped system.
edited to get rid of punctuation turning into smileys !!
Edited by trackcar on Monday 9th October 23:33
Ive been helping a mate map his Grif 500 on megasquirt and can confirm whats been said above - it was much more driveable and easier to live with once we had control of fuel and spark (EDIS8 waste spark) - but at the end of the day, a long duration cam isn't designed for pottering around town in.
rev-erend said:
You will need to cut 2" on the lenght of rubber pipe and use 2 self tapping screws in eack of the pipe ends.
Just as an aside, you are right to block off the spigot at the throttle body, but you can just pull the hose off the vac advance unit at the dizzy and leave it open to the air.
trackcar said:
I've been talking to Dave at Emerald recently about wasted spark emerald ecus for rover V8 so your post is a timlely one if that's one route you're thinking about... they are available 
Edited by trackcar on Monday 9th October 23:33
I think 350Matt requested one a while back and it was the first made..
Its where two cylinders share the same ignition coil (or rather each end of it), they are connected to paired cylinders - so the cylinder thats on its compression stroke is paired with the cylinder thats on its exhaust stroke - both spark plugs get fired, the one thats on the exhaust stroke gets "wasted" because it doesn't do anything.
Have a read here:
www.megamanual.com/ms2/EDIS.htm
Have a read here:
www.megamanual.com/ms2/EDIS.htm
steve-v8s said:
Sorry for being a bit simple, but what is “Wasted Spark”
Each coil is connected up to two spark plugs (one to each end of the coil) so it fires two plugs at the same time. One of these lights up a cylinder at the op of the compression stroke, the other occurs at the top of the exhaust stroke on the 'opposite' cylinder so it's effectively wasted. Hence the name.
It uses fewer components that coil-per-plug (saves money) but also means you can trigger the ignition off a crank sensor - you don't need a cam sensor to determine the engine phase.
leorest said:
steve-v8s said:
Sorry for being a bit simple, but what is “Wasted Spark”
...and what are the pros & cons of it? BTW it's the simple ones who dont ask!
Think I read somewhere that it can help ignite any unburnt gases.. or maybe just ignite them as they are entering the exhaust.. flames
Megasquirt?
It's cheaper, even i can work out how to use it, there are hundreds of thousands people round the world who will know EXACTLY what you are talking about and will fix problems, you can get replacement ECUs for under £200, you can build as much or as little of the system as you like
need i go on?
It's cheaper, even i can work out how to use it, there are hundreds of thousands people round the world who will know EXACTLY what you are talking about and will fix problems, you can get replacement ECUs for under £200, you can build as much or as little of the system as you like
need i go on?
Just so as you all know the Megasquirt ECU links and forum have moved now, the extra code Im involved with is now here:
www.msextra.com/index.php
Ive been busy writting manuals for it all, available here:
www.msextra.com/manuals/MS_Extra_Manual_Index.htm
If you want to buy a ready built ECU then they are available here:
www.extraefi.co.uk/products.htm#wasted8
Phil
www.msextra.com/index.php
Ive been busy writting manuals for it all, available here:
www.msextra.com/manuals/MS_Extra_Manual_Index.htm
If you want to buy a ready built ECU then they are available here:
www.extraefi.co.uk/products.htm#wasted8
Phil
Their main argument (may as well say that it is JanSpeed in Salisbury) for the EFI system was that they are familiar with the units and programming them. They are not an agent, but they directed me towards OBR Motorsport in Ringwood who are. Still think I prefer the Emerald route, just thought I would ask about EFI first.
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