Remap for JDD Gearbox

Kaz

Member
Hi All

So I have had my gearbox in for a few weeks now, and although the car was driveable, there is a noticeable lack in power when changing gears around 3rd to 4th, and 4th to 5th. This is obviously due to the car being mapped for a normal gearbox and not the longer geared jdd as the revs drop so much that the turbo has to respool before the power kicks in.

I have had a generic remap done and this issue is the same - there is more power there, but the range is wrong and turbo has to respool if you know what I mean.

What have people done to over come this? Has anyone had a look at the polo map and modified that to suit the AMF engine?

Kaz
 

rosscanning

A2OC Donor
Hi Kaz,

Glad you managed to fit JDD gearbox, did you know what I meant about the triangle needed to be cut out when you had both gearboxes side by side?
I had my blue tdi running a map known to people on here and thought it suited well for the 50,000+ miles travelled.

Alternatively you could get a custom map done at dark side developments or stealth racing depending on you location, they tailor to how you want it...

Ross
 

Kaz

Member
Hi Ross

Do you know which map it is you have? I have the map from the same supplier - but have found that there is lag in between gears where the turbo is spooling up. Therefore, I was hoping that someone had modified a polo map to these cars
 

A2Steve

A2OC Donor
Hi Ross

Do you know which map it is you have? I have the map from the same supplier - but have found that there is lag in between gears where the turbo is spooling up. Therefore, I was hoping that someone had modified a polo map to these cars
At what sort of revs are you changing up? Could it just be that you are changing too early so it then takes the revs too far outside the power band on the next gear?
 

Menno

Member
Can imagine that you had to take of some intercooler to inlet duct(s) (rhd car(?)) to install the gearbox. Is it possible that there's a hose/duct not secure/tight and gives a pressure leak, and therefore loss of power?
 

Al2coholic

Member
With the longer ratios and final drive more revs are definitley needed to stay on boost. I'll rev to 4k and it'll drop to spot on 2k in most gears until triple figures on speedo. will also occasionally double de-clutch to smooth things out. Can also cruise in 5th from 45mph. its the 30mph limit stuff i find awkward.. too slow for 4th, but too fast for 3rd. results in me doing 25mph in 3rd around town..lucky to get 45mpg from that

MPG definitely takes a hit using that longer power band but can still get the revs super low for those longer trips. still average a reported 59-60mpg in mine.
 

depronman

A2OC Donor
Hi All

So I have had my gearbox in for a few weeks now, and although the car was driveable, there is a noticeable lack in power when changing gears around 3rd to 4th, and 4th to 5th. This is obviously due to the car being mapped for a normal gearbox and not the longer geared jdd as the revs drop so much that the turbo has to respool before the power kicks in.

I have had a generic remap done and this issue is the same - there is more power there, but the range is wrong and turbo has to respool if you know what I mean.

What have people done to over come this? Has anyone had a look at the polo map and modified that to suit the AMF engine?

Kaz
I think you are looking for the impossible Kaz
The JDD in the polo (its natural home) ran on smaller Dia wheels, hence the higher gearing. We are asking a lot of the 3pot TDI to pull these longer ratio, even with a remap
Keeping the engine in the power band, 1800 to 3700 with a remap is key, if the revs drop below 1700 especially in higher gears then you are outside the power band and performance and economy will suffer greatly

I do not think the polo map will make any difference

Cheers,
Paul
 

Kaz

Member
Hi Paul

I think you are incorrect there - the JDD gearbox is not only in the polo, but its also found in the Ibiza and fabia of that era. (circa 2007/2008) These cars came with similar 16" tyres that the A2 has, and looking at the performance stats, they came with 80bhp as standard from their 3 cylinder engines. This has made me wonder if a different map is used to compensate for the longer gearing. I have driven these in the past and didn't notice a lack of power when I change gear like I do with the A2.

Otherwise, the purpose of the JDD defeats the object - if I have to over-rev it to get it going, then I'm losing any mpg gains I may have had by fitting it in the first place.

I'm happy to work with you if you want to create a more suitable map for this conversion if you have the time to do so.
 

timmus

A2OC Donor
If I have to over-rev it to get it going, then I'm losing any mpg gains I may have had by fitting it in the first place.
When the JDD 'box was first introduced as a concept, I played devil's advocate and argued that it wasn't a very good idea, even though I wanted to see someone go ahead with it and make it work. After all, I like to see new options pioneered.

Whilst it does work, and provides a relaxed, efficient way of doing longer distances, I remain sceptical, for reasons noted in the posts above...

I'll rev to 4k and it'll drop to spot on 2k in most gears
The idea of rev'ing a cold engine to 4000rpm pains me. I'll take my TDI120 to 4000rpm when I'm having fun with it, but only once everything has been given a chance to get up to full temperature. On a winter morning, when the TDI can sound like a tin can of spanners, having to rev to 4000rpm just to get into the next gear isn't something I'd enjoy doing.

MPG definitely takes a hit using that longer power band but can still get the revs super low for those longer trips. still average a reported 59-60mpg in mine.
We're obviously comparing apples with oranges here, because your use of your car isn't the same as my use of my car, but I average circa 73mpg with my 6-speed 'box. That's not just 2 or 3mpg difference but a whopping 10-15mpg more. Yes, I probably do more motorway miles, but it'll also be due to me having a suitable gear for every scenario, and not having to rev to 4000rpm all the time. The JDD 'box results in zero gearing flexibility, plenty of scenarios where the engine is rev'ing high or conversely spluttering a little, etc. In urban environments and awkward country lanes, I find it really tiresome to have to manage the huge jumps between the gears. Admittedly, my first-hand experience of driving a JDD-equipped A2 is limited to a few journeys.

I will also occasionally double de-clutch to smooth things out
I double de-clutch with every gear change no matter what I'm driving; it's a totally engrained habit and it feels weird to me to just move the gear stick from one cog to another. The other advantage to this technique is that the 'blipping' of the accelerator pedal whilst in neutral keeps the revs up and keeps the turbo spinning.

I think you are looking for the impossible Kaz ... I do not think the polo map will make any difference
I'm inclined to agree that there is no perfect solution to this problem. A 3-pot TDI coupled to a long-ratio 'box creates a compromise scenario. A map can only work with the hardware it instructs. If a map could be written that was more suited to the JDD 'box, I fail to see why it wouldn't also be suited to shorter-ratio gearboxes. Who wouldn't want more power across a greater rev range? Creating maximum output across the entire rev range is what remapping aims to achieve.

Kaz, is it possible that your turbo is tired? Are the turbo's bearings worn such that it doesn't spool with the same ease that it might once have done, and that it therefore stalls quickly?

Cheers,

Tom
 
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Al2coholic

Member
Unless you predominately sit in 5th gear at A road and motorway speeds. there aren't really any sizable MPG gains to the JDD

The main benefit I think with the JDD is less gear changes [than 6 speed], more thorough use of the power band of a remapped TDI and higher cruising speeds vs the EWQ [or low cruising speeds with better mpg and cabin comfort]
 

Al2coholic

Member
@timmus Please dont think I rev to 4k in every gear all the time and from cold starts 😅 that would be ill advised.

If the engine is warm and I want to make progress, I certainly will head up to the 4K mark, blip of the throttle in neutral and into next gear. great 'hydraulic' feeling of progression down the road. (which I personally get a lot of satisfaction from)

The 59-60mpg is with an average speed of 28mph with around 16miles a day which isnt all that bad ! but only on par with the EWQ gearbox of previous fitment.

The difference however is being able to do 70mph on the motorway and return better figures mpg wise than the EWQ at the same speed or maintain the EWQ lower crusing speed and see north of 80mpg on the DIS... none of this well ever offset the cost of the box though realistically (unless your EWQ lunches itself like mine)

Ultimately you cant beat a 6 speed box for MPG gains and flexibility, particularly on an engine with a fairly narrow power band like the 3TDI
 

Kaz

Member
then how does the polo/fabia/Ibiza overcome this issue with the same gearbox and 3 cylinder tdi engines?

I have checked turbo output and it is fine.
 

Fallan

Active Member
I'm sure they all have the VGT turbochargers and are 80bhp.

I've owned a Polo Bluemotion 2 and they are all pretty gutless - you have to rev them out through the gears to get anywhere swiftly. They are high geared for cruising, i.e intended for people that do long journeys, A/B roads and motorway driving.

You can retain the standard EWQ and have a taller 5th gear which may have suited you're needs better.

The way to go in my opinion if going to all the trouble of changing is to go straight for 6speed.
 

Kaz

Member
yep - I had just read that and was about to report my findings.

I couldn't go with the 6 speed as my car is an early one and doesn't have some sensor that's needed for the 6 speed box. When I got my car, the gears crunched (later found out it was full of water) and I do like the smoothness of the JDD - just annoys me that when I change gear at around 2-2.5k when eco driving, I'm out of the powerband and have to wait until it comes back on boost.
 

Al2coholic

Member
the OE downpipe is a pretty compromised design, exhaust gases have many twists and turn to pass through.

I can report much better pick-up from low down since having mine replaced with a hand built 3" fully tig'd system which has a much smoother
exit off the waste gate (now a smooth 45 degree)

The mistake a made is deleting the rear transverse silencer, it is now a bit too loud and need further refinement but it drives considerably better.
 

Kaz

Member
the OE downpipe is a pretty compromised design, exhaust gases have many twists and turn to pass through.

I can report much better pick-up from low down since having mine replaced with a hand built 3" fully tig'd system which has a much smoother
exit off the waste gate (now a smooth 45 degree)

The mistake a made is deleting the rear transverse silencer, it is now a bit too loud and need further refinement but it drives considerably better.
I don't suppose you have any pics do you?
 

rosscanning

A2OC Donor
Hi Kaz,

This question will be totally irrelevant but did you change gearbox oil? I need to do this and I cannot for the life of me remember what vw bluemotion gearbox oil code was, not sure if you had it to hand.

Ross
 
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