MRC Tune thoughts

[sixspeed]

Prompted by another thread, I thought I'd start my own one on this so as not to take the other post off topic too much.

So I've had the MRC Stage 2 tune (731ps/1023Nm) on my car for about 3-4 months now and overall I'm very impressed with the power the car has, and in terms of sheer performance it's outstanding what can be achieved for so little. I've seen off some very serious machinery and shocked them and myself in the process!

However, it's not without some negatives. Most notably (as my comment in the other thread alluded to) the driveability of the car needs some work, throttle application in particular. Whereas before the throttle was very progressive and gave a good range of adjustability in acceleration, now it seems to behave almost as an on/off switch. Whilst driving around off boost on a light throttle in 'D' is tame, when the revs start to climb there is a surge in power at just over 2k when the turbos spool up, with only a moderate amount of throttle. This is incredibly hard to modulate, the engine seemingly generating a huge surge in torque whether you want it to or not. I guess most of the time it is fine since I usually am just pootling around town, or alternatively I want to unleash all 700 horses and go galloping up the road. However, there are times where it would be nice to just apply a percentage of that power and make swift progress without going all banzai about it!

I suppose the easiest way to describe it is that it feels like anything over 30-40% throttle gives near on full power, and the only difference in the last 50% or so is that it modulates at what RPM the gearbox decides to change gear! Also, once the boost kicks in, rolling off the throttle can result in some rather uncivilised lurching as the boost cuts quite aggressively, and acceleration retards almost instantly.

Overall it feels like the tune is a little crude (for want of a better term) and seems more about the headline power and torque figures, then the way the car delivers the power when you ask for it. I'm curious if this is just my own observation though, or if others with the MRC tunes experience the same? I thought for a while that it was just that I wasn't used to the new way in which the car drove, but having lived with it now for a few months I think more could be done around this area?

I know Doug and Co are constantly evolving the maps, and I hope if they read this (and I am not alone in my observations!) they can see it as constructive criticism, as I am still on the whole very happy with the results!

[neilparf]

Sixspeed - I thought you were selling the C6!?

I don't have a 6 as you know, but the B7 RS4 in sport mode is, as you describe is very 'on' and whilst not Turbo'd does at times give the impression - at certain points of the throttle position - feel like a Turbo on boost!

The contrast of non-sport is far more smoother. I was quite alarmed at the 'boost' like nature of the map in sport; 4K revs in 3rd/4th and the torque is very evident - nice. But, forget you have sport activated at low speed in 2nd for example with the throttle positioned just so and the car can lurch forward provoking a tricky moment...

I wonder if this is intrinsic in the MRC map - accentuated by the fact you have a Turbo and 731PS!

[SuprSi]

If you speak to Doug he will probably be happy to tweak the low throttle part of the map.

I can only comment on the Stage 1+ map he put on my C5 which is very linear on the throttle (although my foot is usually not so linear haha)

[sixspeed]

Sixspeed - I thought you were selling the C6!?

I don't have a 6 as you know, but the B7 RS4 in sport mode is, as you describe is very 'on' and whilst not Turbo'd does at times give the impression - at certain points of the throttle position - feel like a Turbo on boost!

The contrast of non-sport is far more smoother. I was quite alarmed at the 'boost' like nature of the map in sport; 4K revs in 3rd/4th and the torque is very evident - nice. But, forget you have sport activated at low speed in 2nd for example with the throttle positioned just so and the car can lurch forward provoking a tricky moment...

I wonder if this is intrinsic in the MRC map - accentuated by the fact you have a Turbo and 731PS!

I know what you mean, and you get a similar sensitivity of the throttle if you move the gear lever in the '6 to either S or the M manual modes. This enables a "sport" throttle map. But this is a more general feeling, in all modes (including 'D').

It might just be that with 730bhp under the right foot, the throttle requires a dexterity I am lacking, however the throttle in the Z is very sensitive and I can make minute adjustments to that whilst on track etc so don't think I suffer from heavy clobberfeet!

I do think it could be more adjustable tbh, or maybe that's just a drawback of having the increased boost on a turbo engine. I'm not sure...


Oh, and it will be for sale. When I can bring myself to do it...!

[sixspeed]

If you speak to Doug he will probably be happy to tweak the low throttle part of the map.

I can only comment on the Stage 1+ map he put on my C5 which is very linear on the throttle (although my foot is usually not so linear haha)

I did mention it actually when I went in for the map (I actually asked if the throttle map could be dialed back under the 'M' manual mode) and he said it wasn't something they had been asked before, so would require some investigation.

I wanted to see if I was alone though in my experiences or if other people found the tune behaved this way first. I guess if its "just me" it might be that I still need to adapt my driving style to the car.

[Shinobi675]

This is a great thread, I don't believe mines tuned at all, but just this morning driving to the station I was wondering why S is very twitchy (not a problem, I put it in sport for a reason!) while D is slow on the pick up from stationary, then non linear through the gears.

I'd love a different map for the modes. I know this sounds wrong... But I'd want an economy map for D, while a banzai map for S!

I've only had fast manuals before, so it could just be that I've no idea how to drive an auto I haven't even tried blipping gears with the little paddle things...

[Woly64]

Did you have the gearbox map at the same time Sixspeed?

[neilparf]

Mmmm - maybe a gearbox map would help but I do think 730 under the foot will need b=nursing in any mode!

Don't sell it - you'll only regret it!

[R33]

My C6 feels exactly as you describe, I have a stage 2 remap and for the moment no gearbox map (I will get this on my next trip though). Personally I feel it's not as a result of the map but more that it highlights the cars reliance on its turbos. Put that much boost through two turbos and it's going to be quite a surge of power and torque when they come in. I manage it by driving slowly round town in auto on my own or with the family but when I'm on my own on more open roads I pretty much always just use the paddles. This way I find it a bit more linear and predictable as to when the boost comes on and when you change gear. I'm sure it's hard to make it perfect, 700bhp+ is still a lot of power and my view is you're going to have to sacrifice a little bit of drivability with such a large amount of power.

[sixspeed]

Did you have the gearbox map at the same time Sixspeed?

Yup, have the gearbox map on mine as had the filters and secondary cat delete. Now shifts at around 7200 instead of 6800rpm.

I agree, 730bhp is a lot to be accurate with But the car was running 600 before the maps (with filter and cat delete alone), and the power delivery was a lot more finely tuneable (if that make sense?). If I applied 30% throttle I got "30%" acceleration, 50%, 70% and so on...

Now it just seems any more than 30% throttle and I get the whole shebang! Then, as I mentioned above, the only difference throttle position makes is the RPM at which the gearbox shifts. Maybe its less the throttle map per se, and maybe more to do with the wastegate and/or actuators (do we even have these in an otherwise OEM setup? I am clueless...). Should the ECU be bleeding off some of the excess boost generated by the turbos at lower throttle applications? Needs someone more knowledgable than I.

Not sure what the actual "problem" is (if it can be called that), but I definitely think it could be refined to make accurate application of all that power more feasible.

[wrekka]

To be honest i think my standard car is a little as you describe the tuned car already! Really not got to grips yet with the throttle, autobox/paddles etc. Always had fast manuals too. Sometimes i can put my foot down in D and not much happens the next second it is like -Sh*t- boost has just jumped in and I am stamping on the brakes.

[Doug_S2]

We can change this to be less sensitive - throttle response is OE on all our tunes so far but we can change the low revs sensitivity to be more linear

[Fatneck73]

Sixspeed. My 6 with the 702 MTM tune is EXACTLY the same....I just put it down to my ham-footedness tbh. Had my done at QST and cannot rate them enuf.....so am sure it's definitely me not them. They're excellent.

But your description is spot on....maybe it is just 'all that power'???

[sixspeed]

We can change this to be less sensitive - throttle response is OE on all our tunes so far but we can change the low revs sensitivity to be more linear

Doug, that would be great to try out and see if it makes the car a little more adjustable on part-throttle inputs

The more I try to analyse it, the more I think it is probably down to the huge jump in torque available at low rpm. Certainly the throttle curve could benefit in being adjusted in the 30-70% throttle range, along with throttle "roll-off" as it's hard to come back off the throttle without a lot of lurching about.

[Doug_S2]

the more you can tell us, or show us, the easier it will be to do something for you