GTD+

[monkeyhanger]

Short story with Buddy’s seems to be that he’s made full use of the box at max setting and is still making almost 46mpg with less than 1500 miles on the clock. My Scirocco would’ve been making the same around the doors with a heavy right foot and 170PS to play with instead of (on paper at least) 239PS (indicated 50/51mpg, actual 45/46mpg). 40% more power on tap and same mpg seems a canny deal to me.

[Buddy]

Yep spoke to Steve at tdi tuning today. He's cool for me to send mine back for reflashing, a dual channel cable and it would go back out to me with UPS the same day. He reiterated that a bespoke set up in chelmsford allows them to tailor the set up to the individual car but that they are now sending them straight out with typical settings. Fair play.
It's going to be a limp couple of days while I'm waiting for the new delivery.

[monkeyhanger]

Yep spoke to Steve at tdi tuning today. He's cool for me to send mine back for reflashing, a dual channel cable and it would go back out to me with UPS the same day. He reiterated that a bespoke set up in chelmsford allows them to tailor the set up to the individual car but that they are now sending them straight out with typical settings. Fair play.
It's going to be a limp couple of days while I'm waiting for the new delivery.

So basically the single channel box is capable of dual channel processing with the dual channel lead? We see this all the time when things like a £50 calculator has the same electronic architecture as a £15 from the same manufacturer, but the £15 one has a raft of features disabled to justify the higher price tag on the £50 one.

Last night and this morning were a little poor with mpg due to a regen happening, not massively poor - 44.7 mpg this morning as opposed to 47.3mpg (all indicated figures).

[AMarsh]

Interested to know what you feel the traction is like with the extra torque.  It was extremely wet tonight and I really struggled to get any power down without the traction control stopping me in my tracks. I presume there is an adverse affect on grip on first but would like to know if significant. 

Cheers!

[monkeyhanger]

Interested to know what you feel the traction is like with the extra torque.  It was extremely wet tonight and I really struggled to get any power down without the traction control stopping me in my tracks. I presume there is an adverse affect on grip on first but would like to know if significant. 

Cheers!

For me it seems that low end power for moving off doesn't seem any better than stock, but 3rd to 6th is where the difference is to be seen. Bridgestone tyres I presume? Mine are sh!te on initial grip in the damp too - plenty of tramping if you give it more than half throttle on initial pull-away. Bear in mind though that I only have my box on medium setting right now. I'm driving the car as it was driven without the box (with the odd incursion into the extra power) right now to see if there are any genuine mpg gains to be made. On the assumption that MFD mpg calculations are being made by the common rail sensor before the box changes it's signal sent to the injectors, I am expecting to see a 5% deficit between actual mpg and MFD indicated mpg to turn around to zero or even 5% above MFD readings if there are any genuine savings to be made.

I am noticing right now that the car seems to have a bit more low end torque. but sometimes it is asking me (MFD gear change prompts) to drop a gear vs what the unaltered car would have wanted. This happens especially in 5th wanting to drop to 4th when maintaining 32mph, or 4th wanting to drop to 3rd when maintaining 25mph. Sometimes even wants to drop from 3rd to 2nd at 18-20mph.

[AMarsh]

Yeah bridgestones.  I've found the grip to be great in the dry but was really surprised by just how little I had, especially in first, in the wet. 

Decided to leave the car until 1500 miles or so before going with the tuning box.  I totally agree that it feels a bit limp in 5th and 6th, but I am not sure how much this is down to being a brand new engine or whether the gearing is actually set up like this. 

As an aside, I kind of think this why fuel consumption might not be as expected.  Common sense would suggest that being in a higher gear would burn less fuel. I went a drive last night, sitting with the MFD on 'average fuel consumption'.  Really noticeable that any acceleration from a higher gear at relatively slow speeds kills the average, purely down to having the tap open for longer.

[monkeyhanger]

Bridgestones do seem to be the common factor in GTD tramping, for those of us experiencing it. I do feel that they’ve impeded the low end performance a little by fitting these over another brand. They seem worse on a damp road than a properly wet road with laying water. I’m sure you’d get short shrift from a dealer complaining that the tyres are compromising the car and therefore you want them swapped under warranty, even though I am envious of those who got Continentals (and less so – Pirellis). That supposed “anti-tramping” feature touted on the GTD brochure doesn’t seem to work for Bridgestone shod GTDs.


The gearing in 6th doesn’t feel any taller than on my 170TDI Scirocco (about 2200rpm/80mph), but as standard 5th and 6th feel a lot more limp on the GTD. It may be down to the way the power is delivered (it’s a lot smoother on the GTD, but the Scirocco feels racier by being a little more savage – I sometimes miss that). It is a lot more rapid when you look at the dials progressing than it actually feels.

Agree that sitting in a really high gear and putting your foot down is bad for consumption. Sitting in a high gear and wavering by a few mph is fine, but A short burst of hard acceleration to get to cruising speed is more economical than 5x as long for moderate acceleration to reach the same cruising speed. When you can see your instant mpg dip from 55 to 10 for 2 seconds, it’s got to be better than seeing it dip from 55 to 30 for 10 seconds. To be honest I never seem to do anything with 5th but sit between 30 and 40 mph. As long as you’re economical with the rest of your driving to preserve your momentum (anticipating traffic and approaching roundabouts etc), getting up to speed quickly is as economical as getting there over a longer period with less acceleration, if not more economical.

I’ll accelerate in 2nd or 3rd to get up to 30-40mph and then sit in 5th, I’ll accelerate in 3rd or 4th above 30mph to then slot it in 6th at my reached my desired cruise speed that is at least 40mph but could be as high as 80. If I’m sat in 6th at any less than 60mph, I would knock it down to 4th to accelerate quickly, but I wouldn’t drop to 5th. It’s a cruising gear only. 60-80mph, if I need to accelerate, I’ll generally leave it in 6th.

[monkeyhanger]

Just spoke to my dad about his experiences with the TDI-tuning box on the old MK5 170TDI GT. I especially wanted to know whether the discrepancy between indicated and actual mpg changed with the box on, due to MPG assumed to be calculated with the original (pre box-altered) signals to the common rail sensor. I would expect in that case for discrepancy to change in actual's favour so that MFD indicated mpg was closer to actual (brim method).

He said the indicated/actual discrepancy didn't change on his - both values saw gains with the box fitted.

This seems to indicate to me that MFD mpg isn't calculated by the common rail sensor, but by some other method, like an earlier sensor metering fuel volume permanently passed towards the common rail unit.

Or it could mean that by a "feedback" situation, the discrepancy is maintained e.g. box makes car more economical under light/mid loading and therefore less fuel is officially asked for maintaining the discrepancy between indicated and actual. Making the car more economical under light/mid loading should be happening by one of 2 ways or a combination of the 2:-

Increased torque means sitting in a higher gear than would otherwise be the case. Doubtful this would have much of an effect unless you spend a lot of your time at a threshold speed e.g. sat at 30mph in 5th instead of 4th more often, or car sat in 6th at 40mph more often. Can't see massive gains being got here.

Slightly higher injection pressure due to the box modified signals ends up with a more efficient spray pattern than the standard VW set-up, with better atomisation of the fuel in the fuel/air mix. Result would be higher mpg, higher torque and fewer DPF regens as fuel is more completely converted to water and carbon dioxide in the combustion process - making less soot. Could it really be the case that the VW set up of the injectors isn't optimal? Maybe they're governed by a huge "safe" pressure margin, or maybe VW are trying to ensure the injectors last as long as the engine.

There could be a third option. Maybe the box does feck all positively or negatively for indicated or actual mpg when you haven't been tapping much into the power gains whilst you objectively try to judge the mpg gains by driving it pretty much as you did without the box on.

I am almost up to my 180ish miles (as I did without the box) to top back up and see what actual mpg I get.

I will then do a few days with the box at the top end to check out the performance gains. If appreciably better performance comes at too high a fuel cost or driving sensibly shows no mpg gains for me then it'll be going back.

One funny thing I have noticed - yesterday I nipped out at lunch to shoot down the A1 to Costco. I took a colleague with me who's been desperate to sit in the car on a trip. I gave it a quick blast of hardish acceleration once it was warm, a few times. Going down to Costco (mainly flat and downhill) I achieved an indicated 49 mpg for the 7 mile journey. On the way back there is a wickedly steep slip-road from Scotswood road up to the A1 - it's about 3/4 of a mile long and 25% gradient. I pushed the car quite hard up to 70mph to demonstrate the rapid progress even up a hill like that. I could've got up a lot higher than 70mph, but there's a bit of a bend near the top which I wouldn't like to take any higher than 70mph. Accelerated again to 80mph on the straight when joining the A1 and then back to work. Was surprised to see that driving it quite hard didn't seem to have much of a penalty on the indicated value - 46.9mpg for the trip overall, much better than my average indicated since fill up.

Just wondering whether a quick burst on a hot run really helps clear the DPF passively, pushing up your mpg.

[KyleB]

Cheers for the pictures MH, it really does look straight forward to install. I'd feel confident doing it and I'm inept at working with cars haha.

You planning on cranking it up to the max setting at all? Or you happy with it on the middle one?

[monkeyhanger]

Cheers for the pictures MH, it really does look straight forward to install. I'd feel confident doing it and I'm inept at working with cars haha.

You planning on cranking it up to the max setting at all? Or you happy with it on the middle one?

Well my middle setting mpg experiment is almost over - Mon/tues next week i'll be topping my tank back up, seeing what it did on the fuel economy and then having a few days at high power before deciding whether to keep it. I will also see what the legit insurance implications are as mid-week i'll be within a month of my renewal.Will try Adrian Flux (there was a card for them in the box). I have a £264 price with esure for the standard set-up.

You soon get used to the extra torque/power. In my mind right now I can't appreciate the gains because i'm used to them, but I know that taking the box off will leave me feeling underwhelmed with the standard set-up.

It is a doddle to fit. 90 second plug in.