Addendum:
I found this nice interview with Marmorini, Toyota F1's Engine Director:
http://www.autosport.com/news/report.php/id/66771
Q. How significant are the differences between the previous ECU and the standard ECU?
Luca Marmorini - Toyota's Senior General Manager Engine: :
They are significant, not only from the engine point of view but also when it comes to gearbox and gearshift control. The seamless gearshift control is quite a delicate thing and you cannot afford any small mismatch or mistake. The team has done a great job with this but it has involved a lot of development.
People think there was no development at all because we have an engine development freeze and a standard ECU but it was actually a huge amount, comparable to developing a complete new engine. We had a lot of issues involving incompatibilities and had to learn to work within the right parameters.
Q. Is the team still learning about the standard ECU?
LM: Definitely. If you think about what we did with our previous system, we were bringing some sort of software upgrade to each race, not only for performance but also to optimise strategy, so there is still a lot to learn to completely optimise the standard ECU.
We can handle the new device and race with it but I can't imagine we have tested all the possible conditions, so, even though I believe our team did a great job, still there is a learning phase. I cannot assume all the problems are solved and we saw that in Australia when we had to change Timo's gearbox after practice due to an issue which originated from the wrong interpretation, on our side, of how to set the system.
Q. If you look at the behaviour of cars, what has changed?
LM: If you do a back-to-back comparison from this year and last year it is very interesting. The pedal position of the driver last year was much more digital, so already in the middle of the corner it was flat, but the engine throttle was delayed. This year you see that there is a direct correspondence between the engine throttle and foot movement, so the driver has to do on his own what last year the ECU was doing.
It's more difficult for him to go on the throttle, but of course we are helping by making the engine smoother. In the end the difference in lap time is minimal but there is a greater risk of a mistake. Over a race distance or with variable grip conditions there is more stress for the driver.
Q. Do the drivers say engine braking is a bigger issue than the traction control?
LM: With the new regulations it was easy to focus initially only on the lack of traction control and underestimate how important the engine contribution was to effective braking, but we found this was quite significant to the driver. The driver has to be careful in variable grip conditions because the braking instability can mean him losing control of the car. Within the regulations we can use some engine maps to help a bit but it is very little compared to last year.
Q. How much has the start procedure changed without launch control?
LM: It is dependent a lot more on driver skill. We can use a special launch map with less engine response at low throttle openings (not at full throttle), so the driver can better control the wheelspin, but we have to use this map for 90 seconds so it cannot be too extreme, otherwise you risk spinning on the first lap.
Full throttle means full throttle and you cannot chop it. If you make a throttle map that is very gentle initially and then very harsh, it would be risky on the first lap when the driver is fighting for position. The emphasis has to be not only on launch but also on first-lap performance - you don't want him spinning when he gets to a hairpin, for example. The regulation is designed so that you cannot help the driver too much with the special launch map.
it seems to me with Williams being down in the grid position, the ability to not make that initial ECU map for 90 sec at launch could be hurting them in those tussles at the start in terms of going from low part throttle to full throttle - the "launch" map would have a more abrupt transition between the 2 compared to their "race" maps.
As Marmorini said, all the teams are learning how to customize the SECU programs to the various tracks still and it seems the Toyota powered teams may not have that all sorted out relative to the others in terms of performance extraction.
I get the sense though that their problem isn't engine or SECU related in development to keep up with RBR and Renault. It's the aero and use of the Bridgestones and dialing in their setup for qualifying.
