FEAR THE NEW TECH
Bikes are getting tricker and smarter all the time. Ride-by-wire throttles, rider power modes, traction control, Euro 4 emissions regs – they all want to keep more and more control of the engine and its fuelling. Closed loop fuelling is one big problem – the bike has its own stock oxygen sensor in the exhaust headers, and analyses its own gases (a bit like BJ after a big curry), aiming for the fuel/air mix the manufacturer has set.
In theory that’s great, reducing fuel consumption and improving running. But if you want to alter the fuelling with a piggyback controller, the ECU will sense the change itself, and try to modify the mixture back again, fighting the changes the Power Commander is making. Remove the oxygen sensor altogether, or replace it with a fixed sensor set at the ‘correct’ value, and some modern ECUs take a proper huff, lighting up warning LEDs, and going into low-power limp-home modes.
With ride-by-wire, the problem is even deeper – when you open the twist-grip 100 per cent, the throttle bodies don’t necessarily open 100 per cent. In lower gears, the bike will gradually open the butterfly valve blades, giving more progressive power. So there are different maps for each gear – then rider power modes, and traction control algorithms also take charge of the throttle at certain times. Working through all this is a massive job for the tuners.
We spoke to Frank Wrathall of Dynojet UK, and Dynojet US senior project manager Dusty Schaller, and asked them about the problems with tuning the latest engines.
Are you facing difficulties with modern bikes? That is, closed-loop fuelling, ride-by-wire, power modes?
DUSTY SCHALLER: There are always challenges as technology progresses. The closed loop area has always been one of our biggest challenges. We need to find a way to optimise the closed loop area as best as possible.
Some of these bikes are quite difficult in doing so and more and more models are coming stock with O2 sensors. As bikes go Euro 4 compliant I would imagine they all will have O2 sensors. On many models we have left the stock closed loop area alone and simply mapped outside of it.
FRANK WRATHALL: We have found ways to utilise the advanced closed loop areas in certain bikes, such as the Honda MSX125 and latest Kawasaki ZX-10R. We have a device to output our own narrow band signal to keep the closed loop area, change the target AFR (air-fuel ratio) to whatever we require. In effect, the ECU goes and tunes itself to our target.
DS: RBW is not an issue for us in most cases. We have always taken the stance to get the TPS reading for the Power Commander from the blade in the throttle body. Some of our competitors choose to get this reading from the twist grip sensor which makes life easier for them but also ends up makes the mapping inaccurate.
By getting the reading from the blade angle we are always mapping to what the engine is seeing, not what the rider input is. Therefore when you switch riding modes or traction control kicks in the AFR will still be correct. This does make mapping on the dyno more difficult.
FW: Different riding modes use the same base fuel table in the ECU, this is the table we base our changes off. Therefore, no matter what the riding mode, the fuelling will be correct.
Do IMU-based systems – with lean-angle traction control and ABS – pose any problems for tuners using PC etc?
DS: No.
What about supercharged bikes, like Kawasaki’s H2? Is the PC able to work with those? Will there be any difficulties with future turbo and supercharged bikes?
DS:
We’ve actually had great success selling to the H2 owner. These bikes are normally quite rich from the factory and the PCV allows good gains over stock. Mapping these bikes is really no different than any other. Superchargers are much more consistent in boost than turbochargers and this allows us to build a map in the same way as a normally aspirated engine.
All PCV units have a 0-5v analog input and if you wanted to tap into the stock boost sensor you could bring that signal into the PCV and build a fuel map solely based on manifold pressure. This works best on aftermarket turbo applications. You can use the RPM vs TP table for off boost and then use the pressure table for when boost is applied.
What would you say the benefits of PC over ECU flashing are?
DS: The benefit is ease of use and real time changes. Although there are advantages to flashing your ECU you still need to get a good fuel curve at the end of the day. Most of the companies that offer a reflash service do not provide tunes to optimize the fuel curve, especially for your exact setup.
So many of these customers get their ECU reflashed and still run a Power Commander to do the fuelling side of it. The Power Commander is something that most people can wrap their heads around and feel comfortable making fuel changes, especially when they can see the effects of the fuel changes happen live. The map database of the Power Commander is second to none so it is easy for the end user to buy a product, download the map for their set-up and know that their bike is running the way it should be.
FW: You have a tangible asset with a resale value. The Power Commander comes with software for your PC and a USB cable, so in one simple connection, the end user can see the changes, and even alter the fuel map. More control lies with the owner than in flashing.
The end user can use the Power Commander as a diagnostic tool, seeing individual duty cycle of the injectors and TPS voltage for example.
There are no permanent changes to the bike. This helps if the bike develops a problem. If you can remove the remapping device, you or the mechanic know you are dealing with a stock bike which make diagnosis and repair a lot easier. If the bike has suffered severe detonation and the ECU has been reflashed, it can be incredibly difficult to source the problem and cure. Has ignition advance been added to the ECU flash, how can you find out? Can you trust someone to put the ECU back to standard? No permanent changes to the bike mean you can remove the Power Commander to sell the bike or have it as an optional extra to expand your potential market. You don’t have this luxury with a flash.
If you make changes to your bike, (different exhaust etc.) you can easily load a map into the Power Commander for that given setup, for free. You would have to pay to get your ECU reflashed.
The extra Power Commander inputs and accessories can easily give advanced tuning capabilities over some flashing software, such as, gear and/or individual cylinder mapping, pit lane speed limiter, quickshifter, switchable maps, launch control, auto tune, etc. If you add a Dynojet ignition module to the Power Commander (integral on some models) this allows ignition changes and even allowing rpm limits to be raised on some bikes.
The humble dyno run
The heart of any fuel tuning is a dyno run. Anyone who says they can sort out your fuelling without one of these puppies in their shed is talking out of their collector pipe. Dynojet’s setups are more common, and they work well with Power Commander tuning, but a skilled operator will be able to sort any refuelling setup with any dyno, pretty much.
Your bike is strapped onto a big metal machine, with the back tyre on a heavy, rotating drum. The dyno man (or woman) runs the bike up, and the speed that the bike can accelerate the drum gives you a torque figure, and from that, a power figure. An exhaust ‘sniffer’ samples the gasses coming out the engine, and can work out if the motor is running rich (too much petrol), lean (too little) or spot-on through the rev range.
We want more than peak power runs though – we need to hold the engine at a certain rpm and throttle position, so we can analyse the exhaust gasses at each point. So we need a slightly smarter dyno – one with a ‘load cell’. That connects the dyno drum to an electric generator set, which applies an opposing force to the drum, holding it at a steady speed. Once the bike settles down, the gasses are analysed, and the operator can see if the fuelling is correct.
So, your dyno man will sit with the bike, and starting at around 1,500rpm, say, he’ll hold the throttle at 2 per cent, let the drum speed stabilise, note the fuel mixture readings, and that lets him put the correct offset into the Power Commander mapping software. If it’s lean, add more fuel, if it’s rich, take some away.
Then he’ll go up to 5 per cent, and do the same, then 10, 15, 20, 40, 60, 80, all the way up
IF SOMEONE SAYS THEY CAN SORT YOUR FUELLING WITHOUT A DYNO, THEY’RE TALKING OUT OF THEIR COLLECTOR PIPE...
to 100 per cent throttle. Then he’ll do the same at 250rpm increments, all the way up to the peak power engine speed. There are some mismatches at low throttle/high rpm and vice versa where you can’t really map properly of course – most motors won’t run to the redline on 2 per cent throttle, and at 100 per cent throttle, there won’t be much time spent at 1,200rpm. So changes are less important here.
The Dynojet software can ‘interpolate’ between the mapped points, that is, take an average figure, to give a smooth progression as the engine speed changes. Once the fuel/air mix is corrected at all the throttle openings and all the engine speeds, the engine should be running at its absolute best…
Fitting a Power Commander
If you know your way round your bike, fitting a Power Commander is a pretty easy job. The hardest part is usually getting access to the fuel injectors, which will normally be under the fuel tank/airbox. Find a spot to locate the main PC unit, usually under the seat, and secure it with Velcro and/or cable ties. There’ll be a connector to the negative terminal on the battery, a tap into the throttle position sensor (TPS) on the injector bodies, and then four pairs of male and female multi-plugs, which sit between the fuel injectors and the stock wiring harness.
Unplug the stock connector from each injector, plug it into the corresponding female plug on the Power Commander wiring, then plug the PC male plug into the fuel injector. Do all four, put the tank back on, check the bike is running okay, then grab a cold beer!