Part 6 - Other jobs, fine tuning and drives out
The Christmas period over here was just rubbish in terms of weather. Wet, cold and slippery. Not the weather for being a hero but I did get the car out once for a quick spin during that time. Lucy and I have also been on a few days out, which has been great. Something I have noticed, and chatted over with Chris (at Northampton), is the throttle pedal actuation rate. This is all fully tuneable, but at present the boost targets at various opening %-ages feels just a little soft to me….the pedal feels quite long with the high boost targets being pushed out to high throttle positions. It kind of made the car un-energetic during normal driving.
So, last week we scheduled a remote dial-in session to change these a little and also to show me how to do this myself, so I can tinker with the calibration self-sufficiently (dangerously, lol!).
There are two areas that can be changed in the Syvecs SCal s/w; the Pedal Position Sensor (PPS) to Throttle Position Sensor (TPS) Target is one strategy, but not the one he recommended to play with at the moment.
The more interesting one is the wastegate control strategy, which sets the manifold target pressures relative to the PPS and the gear.
Comparing the current calibration profile against the one I'd been using up until December, they are both similar in terms of the shape of the graph (neither are linear), however the "old" profile had a boost target of 30% from 0 revs. The new profile started at 0% boost at 0 revs. This therefore meant a steeper ramp toward the higher rev range, hence the "all hell let loose" sensation.
I've now reverted back to the old profile, and given it only a few shortish test drives. My first drive wasn't particularly successful for very different reasons....6 miles into the drive, minding my own business and in town traffic at 30mph, I went to accelerate and heard a very loud tractor. My tractor. "OMG, what just happened??!" A quick stop at the side of the road and it's very clearly exhaust related, but nothing looked to have fallen off. A bail-out route through the back streets, and a gentle limp back home followed by a cup of tea and a very quick inspection revealed....absolutely nothing that was obvious. No leaking head flanges, silencer is still bolted to turbo, no visible cracks in the manifolds. Oh no. Perhaps something more serious...or maybe a fracture within the heat exchangers? Slightly baffled, because the engine was barely up to temp, so no boost up until this point. Anyway, I got roped into Covid related hospital runs for the rest of the evening/night....left hoping it wasn't something catastrophic like a dropped valve.
The following morning, early start, time to get the car on the lift for a proper inspection. Firing up the tractor, the noise seemed to be coming from the turbo area....was the housing cracked? Not that I could see, albeit with a heat shield hiding a lot of it. And then I saw it.....one of the blanked off Lambda sensor ports on the secondaries, that I had originally welded in there when intending on running 2x sensors. The one directly under the turbo compressor housing. A quick check with a piece of bent wire (it was too hot to use fingers) confirmed that it had made a bid for freedom but had left the ally compression washer in place. PHEW!....that's only a £5 and 5-day-wait problem to fix....unless.....
At this point Dad appears with doughnuts in hand (hahaha) suggesting a coffee and chat. Good plan, was just regailing the story-so-far and he pondered the same thing as me...."Wonder if we can retrace our steps and find the blighter?" Coffee on hold, jumped in the car, we split up to speed the operation and 5 minutes later he called me to say he'd found it!....no bid for freedom today, Mr Lambda Bung....
Miraculously no threads were harmed in the making of this tale. A quick wire brushing later and it's back in place. Some fenaigling of tools to be able to tighten it (the first time I've ever been able to make use of these socket>ring spanner tools). A completely uninteresting story really, other than FOR ONCE the hunt for a lost part turned out to be successful. What are the chances....
And we'll try that test drive again, shall we?.....
The car down at St Margarets Bay, near Dover. The "White Cliffs Of Dover" are in the distance in this shot....
....and the white house in the distance at sea level used to be owned by Noel Coward (playwrite, actor, singer....Mr Bridger in the original Italian Job), who then sold it to his good friend Ian Flemming....
So, has the PPS>Boost map change made a difference? It does feel a little more hair-trigger, naturally. But with the new super smooth throttle pedal, this is far more manageable than it once was. However, it also feels significantly more energetic and lively...."spirited" even. With normal road speed driving, it now feels extremely responsive, with just a very gentle squeeze of the throttle to teleport you right up and close any gaps in traffic. It also means that the previous transition from normal/relaxed to full-send is far better. Not as violent or pronounced because you've been building more boost up until that point, but is nicer and more controllable, really using the strengths of the twin scroll turbo and its building of boost lower down.
The profiles both have the same curve for all 5 gears, there really is no need that I can see (for the time being, at least) where we need to soften things in 1st and 2nd. Of course, if you go at it like a bull in a china shop, you'll break traction very easily, but appropriate driving presents no issues at all, even in this filthy weather.
I may well have a play and build a graph that's a hybrid of both, just for the sake of playing and practising....we'll see. Chris and I did mull over that actually rather than having a multi-boost switch in the cockpit (which actually, we never change), it would be more useful to have that switch dial in different throttle characteristics, just like motorbikes do....they all deliver the same hp/torque, but in different ways. Unfortunately, it looks like my Syvecs S6+ can't do this, but the latest S7's can....but really, is it *that* useful? This is meant to be a fair-weather toy rather than a daily drive....