At 60mph on a dry motorway in 5th gear I suspect not.

Ah... sinks away into pit! digs thurther!

Just to add, my understanding of turbo lag is the time taken to spin up from below the usable rpm, i.e. it doesn't happen at 2.5 to 3k rpm where the turbo will already be spinning and the engine is at 3/4 maximum revs.

No, this is wrong. The following is taken from http://www.turbochargedpower.com/Common%20Terms.htm.

Turbo Lag

Turbo lag is often confused with the term boost threshold, but they are not the same thing, lag is nothing more the the delay from when the throttle is opened to the time noticeable boost is achieved.

Boost Threshold

Unlike turbo lag, which is the delay of boost, boost threshold is the lowest possible rpm at which there can be noticeable boost. A low boost threshold is important when accelerating from very low rpm, but at higher rpm, lag is the delay that you feel when you go from light to hard throttle settings.

This is a common mistake that many so called professionals even make. Jeremy Clarkson is a typical example. When he was reviewing the EVO FQ400 on Top Gear, he raced it against a hire car by accelerating from 30mph in 6th and blamed its poor performance on Turbo Lag. This had nothing to do with turbo lag, it was just that the FQ400's turbo was below its threshold rpm.

Thanks for the info alock, my understanding of turbo lag was wrong, but I am not convinced this is the issue I have experienced.

Let me give some more detail: When accelerating in 5th gear up to 2.5k rpm and easing off the throttle before pressing it again (no stamping) there has been relapse in power before acceleration commences. It's as if a misfire has occurred with the engine before power comes back.

To put this in perspective, when the car is driven flat out and I change gear there is a momentary pause before acceleration commences in the next gear. This will be turbo lag I guess caused by my right foot coming off and back on the throttle in a heavy handed way. The two instances are completely difference as the earlier scenario is gentle throttle lift followed by part load and a sudden momentary loss of power.

" To put this in perspective, when the car is driven flat out and I change gear there is a momentary pause before acceleration commences in the next gear. This will be turbo lag I guess caused by my right foot coming off and back on the throttle in a heavy handed way. The two instances are completely difference as the earlier scenario is gentle throttle lift followed by part load and a sudden momentary loss of power."

Yep; exactly the what I experience in mine. It's most obvious when you accelerate from part throttle.

...The two instances are completely difference as the earlier scenario is gentle throttle lift followed by part load and a sudden momentary loss of power.

I've been having a read around and several people have been complaining about similar issues with the latest Merc diesels. The reason seems to be fairly technical and based on how a throttle in a diesel works. In a petrol, the throttle controls the amount of fuel and air entering the engine. In a diesel, the throttle only controls the fuel, so the fuel/air ratio changes. This sudden change in fuel/air ratio is what normally causes the puff of black smoke when you put your foot down. Apparently, Merc have changed their electronic throttle to minimise this puff of smoke. The side-effect is that it can add a delay to the application of power.

Now, the questions I can't answer (being new to diesels)

- Does this hesitation appear in the same scenario that you might expect a puff of smoke?

- Does the 2.0TDi smoke less than the older 1.9TDi?

If the answer to both of these is yes, then could this be an explaination.

so is nobody reading my earlier post?

Still sounds like the part throttle problem I have and easily confirmed and tested...

Garv the standard plot link doesn't work.

Everyone else with this hesitation. Can you tell me if you lift off the throttle 100% before applying the throttle again?

I only as ask the most annoying thing about the 20TDi to me is the first entry on the throttle table is too high.

i.e. if at idle (800rpm), try to apply the throttle to get 900 or 1000 rpm, can't be done, it's straight to 1100 or more because the first position on the electronic throttle i too high. I'm assuming this is by design and not a fault on mine (would appreciate feedback).

Just wondered if the hesitation you feel is actually the jerk caused by the jump in throttle opening.

I think that you have hit the nail on the head . There must be something on the electronics that control the throttle that is designed to make gearchanges smoother. if you drive away gently with your window open and listen to the engine as you change gear you will hear the throttle give a tiny "blip" of the throttle to eliminate what must be a flat spot around 1000 to 1100 rpm. This is more pronounced in my octy 2.0 tdi than it was in my Passat 1.9 130 sport and it makes you concentrate a bit harder in slow traffic when crawling in 1st or 2nd gear due to a surging effect when it tries to cut out the "black hole" around 900 to 1100 rpm.

Power deliver seems a bit softer than the 1.9 130bhp but revs better and less need to keep it in the "sweet" rpm area.

Some interesting points there, which leaves me to believe it's a combination of throttle position jump and anti-smoke technology. But it seems odd that I have only experienced this at motorway speeds and the fault is intermittent.

Maybe if we all complain enough Skoda will isue a new ECU map to eliminate the problem.

Well folks, coming home from work tonight I was able to reproduce the fault in second gear by lifting off slowly and rolling back on the throttle at just over 2.5k rpm, so it would seem speed is not an issue. What was interesting is that car was fine when warm and I was unable to reproduce the 'hiccup'.

Does a diesel engine run with a richer mixture when warming up like a petrol engine?

If so, then the jump in throttle response, combined with anti-smoke technology and the punch of maximum torque coming in could be what I am experiencing.

I'd never noticed that gap between 800-1100 rpm until I tried it this morning. Mind you if I've just noticed it, its not causing me a problem....

Driving home today I'd could'nt get the hiccup whatever I tried; different speed,gears and throttle position/action ;DOH. But I don't tend to floor the throttle so I agree ; it tends to happen more at gentle throttle action.

Octy 2 on drive

Lawnmower in garage

I have been reading this thread and the problem sounds familiar. I assume that 2.0TDI shares quite a few similar parts with the older 1.9TDI. If this is the case then you may want to look at this thread.

http://www.briskoda.net/forums/showthread.php?t=29474&page=2&pp=15

Some of the symtoms may not be the same, but i have experienced the same problem, as have some other members.

Its worth a look. Sounds to similar to ignore.

Best of luck

JD

PS. mine didn't show up on the diagnostics either!!

This is a known problem with the 2.0TDI. Check over on www.uk-mkivs.net. A guy called Foxy had this problem and has posted a fix for it.

Here is the link to the post:

http://www.uk-mkivs.net/forums/259601/ShowPost.aspx

We could do with the actual VW technical note really to give to the dealer as I suspect Skoda will refuse the warranty claim.

Good Work Sherlock

This is a known problem with the 2.0TDI. Check over on www.uk-mkivs.net[/url']. A guy called Foxy had this problem and has posted a fix for it.

That link does not work for me

here is the chart of a 2 litre TDi 140 the dip in bhp and torque can be seen with no problem!

AUDI A3 EDC16 140 STD.pdf

Interesting graph, although I would question why your cars power starts to decline at the wheels after 3500 rpm, yet the power at the fly wheel continues to rise until 4000 rpm. The torque curves seem to suggest they should run parallel.

I think this is a completely different issue to the hesitation problem we are experiencing and my first thought on this matter was a faulty valve, which Foxy mentioned on uk-mkivs. If anyone has got a copy of the VW technical bulletin then this it what we need to instigate a warranty claim with Skoda, otherwise we'll have a hard time convincing them this is a problem.

Agreed ; I showed my dealer the golf1V detailed note but they reckon the EGR valve is more likely the problem and have ordered one (or so they say) :confused:

Interesting graph, although I would question why your cars power starts to decline at the wheels after 3500 rpm, yet the power at the fly wheel continues to rise until 4000 rpm.

This is due to the increase in transmission loses

Is there some reason why the remapped engine doesn't suffer the same transmission losses?

Sorry, just realised it's a different car. The gains with the remap look pretty good.

Returning to the original thread my dealer has replaced the EGR valve now and it seems to have cured the problem.

Bu**er the hesitations still there. Anyone been cured yet?

Haven't noticed it on mine so the problem has maybe been resolved or I just haven't encountered it yet. The car was delivered to the dealer first week in September.

Autocar magazine had a long term test Ambiente 2.0 TDi for a year up until September and really loved it but the part throttle hesitation never went way and they never got to the bottom of it. It's not a lag problem though.

Started to notice it on the loan car I have, it's a 54 plate 2.0 TDi with 14.5k now on it....

Not sure if this is the same thing but I