Skoda superb 2.5 tdi giving me a lot of trouble!

[vk10]

Good Morning to all of you, Hope you have enjoyed the bank holiday weekend. I have successfully covered about 2600 miles on the superb in the past month. Have regularly checked the timing on vagcom and is still at 0.6-0.8 ATDC as suggested by diesel v6, even though when you actually go into tdi timing graph it shows -0.8

Have noticed a few things on it, 1st gear great, 2nd gear great and when it goes into 3rd mid-way it drops into another gear as if its a 6 speed transmission which it isnt. and then we have 4th and 5th. I have read around on this and its to do with the dsp wanting to be switched off etc. I don't know the procedure for it as yet but would like to know your views on it with the experience i have had so far and the help I have revived from this forum i swear by this forum!.

2ndly the fuel economy is really bad compared to my old 1.9tdi, i seem to get about 400 on a motorway run. Is that normal? Tip computer shows 46-48mpg but when calculated from brim to end its no where near the 40's. There is no power loss, pulls well. Woulds a re-map be any good for it?

Morning start up is good 1st crank no smoke, though there is plenty of it under heavy acceleration Over all great driving experience, but seems like the gearbox isnt really matched up to this car, its a confused one.

Would appreciate your views!

[Gaz]

2ndly the fuel economy is really bad compared to my old 1.9tdi, i seem to get about 400 on a motorway run. Is that normal? Tip computer shows 46-48mpg but when calculated from brim to end its no where near the 40's. There is no power loss, pulls well. Woulds a re-map be any good for it?

Would appreciate your views!

I've a 2.5 Tiptronic too. My last tank was my best in over a year, and was 39.1mpg overall, including a steady trip up to Norwich and back. Usually mine's in the early 30's.

Would what you describe happening in 3rd just be the torque converter locking?

Gaz

[vk10]

i think that's the right term torque converter locking, Its something like the import japs had "overdrive mode" but that usually kicked in top gear but what im experiencing is in the 3rd, revs drop slightly engine note changes and power kicks in.

[Cown]

I wouldn't expect "good" mpg in that car and i would definitively not compare it to 1.9 TDI mpg.

[JonathanK]

I have the same auto box issues but not just in third, could be second too. Also, on first start off when cold it feels like the the gearbox hasn't 'engaged' and then it catches up with itself and off it goes. Seems to coincide with a relay somewhere down in the drivers footwell above the go pedal kicking it but that may just be my imagination.

[CRC]

I'd really recommend Millers Eco-Max for the V6 engine, as it seems to love the stuff. I bought some back in the winter and it's just smoother and crisper throughout the entire range, and now I never see any smoke at all .... nothing at start up and nothing under heavy acceleration.

It costs about £12 for half a litre but at 1000:1 dilution (as recommended) it will treat 500 litres of diesel ( about £700 quids worth.)

Maybe a very slight improvement in mpg, but cleaner, crisper and smoother throughout the rev range imho.

Seems strange that your trip computer shows a mpg that is so far out from your actual "brim to brim" calculation?

I also get a "trip computer" 47 mpg on A roads ( 6 speed manual), and though I've never never actually done the "brim to brim" test, the infrequency of having to pull into a garage makes me think that it must be somewhere near right.

Edited 28 May, 2013 by CRC

[Gaz]

400 miles on a motorway run does seem on the low side, but might that be your driving style? My 340 mile round trip to Norfolk returned 44.6mpg, but that was saintly driving, with cruise wherever possible, no speeding at all and reading the road way ahead to prevent having to adjust my speed. I could quite easily have barrelled along and got early 30's. Here's (attached - wouldn't upload :think: ) my last ten to give an idea of what mine's like if you're interested.

It might be that I'm used to the gearbox, but mine doesn't 'feel' confused. Not up to jap boxes (my last car had the Aisin Warner 55-50, which was particularly well coupled to a 250bhp Saab Aero) in my opinion, but it does the job well enough.

Gaz

superb fuelly.pdf

[vk10]

Crc, have ordered the millers eco max today. Just out of curiosity what timing is your injection pump set at? Is your car remapped?

V6tdi the same is ur car remapped? And what injection timing is yours at on vagcom

Aisin Warner is a good enough gearbox we have it on my brothers s80d5 auto, which does 650miles to the tank and puts mine to shame.

[CRC]

Not exactly sure what my timing is set at ..... I keep meaning to borrow a vagcom laptop and have a look. When we did the timing belt change, we marked the positions and put things back together as near the marks as possible. It starts fine, but not exactly on the first turn, so I would imagine that it's slightly out.

As I understand it, the "static timing" of the VP44 is set by the positions of the belts and pulleys and that's what the pump uses when the engine is cranking / idling. The software takes over once the engine is up and running and needs advancing etc.

It's not re-mapped .... I did look at the option, but if I'm honest, I've got plenty of power and plenty of torque, so I couldn't see the need for it.

When it comes to mpg, bear in mind that below about 1800 rpm, the turbo is not cutting in, so the engine is acting as a normally aspirated diesel and that the maximum torque on these engines occurs at 1200 rpm, so the way to achieve good fuel economy is to keep the revs between 1200 and 1800, which the V6 will happily do.

Also, mine is the 6 speed manual (which makes a difference) as there's very little hydraulic drag going on inside the gearbox, and it also makes it easier to "coast".

Hope you find the eco-max works well .... mine loves it. Also, after your experiences with the massive amounts of smoke due to the faulty VP44, I suppose it's possible that the cylinder heads on yours are really in need of a de-coke and this stuff can only help.

[Gaz]

V6tdi the same is ur car remapped? And what injection timing is yours at on vagcom

Mine's boggy standard, no remap. Cambelts changed last year but it's cranked over a couple more times since on really cold starts. I asked Skoda to check and adjust, but all they managed to tell me were warm starts are fine - 10/10 for stating the obvious. Numpties. I'm afraid I'm none the wiser as to the injection timing.

Gaz

[vk10]

They are numpties all right,I know that since they apparently change cambelts without changing tensioners and water pump.

Lets hope the millers make a difference because based on this mpg the mileage iam going to start doing is going to cost a lot more. Maybe I should have just opted for a 1.9 in the first place!! But too late now.

I'm looking for anyone on this forum who has remapped the 2.5tdi and seen better mpg and also if someone has disabled dsp on the gearbox via vagcom.

[vk10]

Crc, can i add all the 500ml of millers to half a tank of fuel? Or do i need a full tank?

Thanks

[CRC]

No, you just use one ml per litre of fuel, so if you have half a tank of diesel, I would put 50 ml in initially and then just add one ml per litre whenever you buy some fuel. It will mix fine in the tank if you add it after fueling.

[vk10]

Thanks, will added it to the tank. Will wait for the results, are you all coming to the meet on 28th July?

[oh_superb]

The MIllers stuff is just a cetane improver, no magic there, any diesel car will like it some more some less.

My lifetime average is 38.95 mpg (7.24 l/100km). Just returned from a pan-european 3000 mile round trip and the worst I got was 37mpg (Hungarian motorway, pretty steady 90mph agains wind and with lots of cross-wind and rain). In Germany I got 38 mpg, cruising at 90-95 mph whenever possible and respecting overnight speed limits. Best was 46 mpg doing 70-75 mph in Serbia (flat road, no traffic, cruise control, no A/C).

So this gives you an idea.

I have "vented" my tank so now I get 500 miles to a tank. It will swallow around 61 litres now as opposed to 53-54 litres before the mod. Now I can do 80 odd miles before the fuel needle moves off the max mark. Previously it moved off the max within 20 odd miles. Pathetic. My range was also around 400 miles, driving in a spirited but anticipating manner (minimum braking).

I also have the tiptronic "additional gear syndrome". Have always had it, but these boxes are plain old slushers, I guess at least you could say they are relatively reliable compared to that modern DSG stuff....

Edited 2 June, 2013 by oh_superb

[Cown]

Vent modding is a must on these cars.

[vk10]

I know the modern dsg has the horrible flywheel issue, but i honestly think,its much better than this over revving undergeared gearbox. My last a61.9tdi had a cvt box which was fantastic (yes i know the horror stories on the gearbox ecu and premature failures but if fixed with the upgraded 7 plate clutch they are fantastic. Anyway coming back to this topic, i just did a round trip of 200 miles which has approx cost me 40quid @135.9 a litre which equates to 30.4 mpg steady motorway driving cruise control at 70 . And plus plenty of black smoke

I have plugged in vagcom and gone into basic settings tab 004 and it reads 1.8-2.0 Atdc

When i click on tdi timing it reads -1.8 to -2.0. Switch back to basic settings it reads -1.8 to -2.0 btdc. Not sure what to make of that as timing is within spec. Starts on the key and power is great. Mpg is terrible and smoke is evident under light acceleration as well (specially at night can see it in others headlights).

I have used the millers stuff and its not made any difference. Any suggestions?

Thanks!

[CRC]

Below is part of a dieselV6 post from earlier in the thread. I haven't done this myself, but it would suggest that there are there are two timing points which can be seen.

The "late" one is the "cranking, starting, idling" value that needs to be right for good starting. This is set by the position of the belt and pulley and you've got that right.

The "early" one is the one that controls injection timing when the engine is "flying". This is controlled from the ECU and should be around 15 degrees BEFORE TDC. This means that when the when the pistons are hurtling round, the system squirts fuel in before the piston has reached the top of its stroke, but the piston is now travelling so fast that the combustion (and resultant bang) happens AFTER TDC so that it pushes the piston downwards in the correct direction. If the fuel goes in too late, then it will be trying to ignite as the head pressure and hence air temperature is reducing, meaning incomplete combustion. Sounds like that's what is happening?

What are the "early" values reading?

In basic settings group 004 (not measuring blocks!), the timing is set to "early" for a period of time (10s I think), then "late" for another period of time. It is alternating every 10 seconds and VCDS shows that.

When VCDS says "early" in the window next to timing value, it should show around 15deg BTDC, ie earliest timing possible, which would normally be only used at high revs and max fuelling. When VCDS says "late", it shows default idle injection timing, it should show about 0.8deg ATDC for good cold starts, though you may find up to 3 deg ATDC there. But the "late" value should not fluctuate more than 0.3deg each way on a fully warmed up engine.

Engine temperature must be 85degC at least for this test.

Edited 7 June, 2013 by CRC