Hi guys, do you know what can cause this slight loss of rpm when accelerating with my Octavia 1.5 tsi dsg? 

It's happening only when I press hard on gas pedal on low speeds. No errors on dashboard. Car is working perfectly in every other circumstances.

Car has 110.000 km and new spark plugs, car battery, engine block breather and checked fuel injectors which are fine.

Is this something about DSG? 

Hello, welcome to the forum.

That looks to be perfectly normal drop in revs due to gearbox upshift.

11 minutes ago, Warrior193 said:

Hello, welcome to the forum.

That looks to be perfectly normal drop in revs due to gearbox upshift.

Pay attention on rpm drop at the very beggining of the video. It stays in 2nd gear, around 1500 rpm it drops to 1200 but my foot is constantly on a gas pedal. When it does that, car stutter. Very annoying when going uphill (very steep hill).

The only thing I can see is normal operation during upshift. You could expect to see a slight hesitation on throttle-up due to turbo-lag at low revs - again, completely normal.

2 minutes ago, Warrior193 said:

The only thing I can see is normal operation during upshift. You could expect to see a slight hesitation on throttle-up due to turbo-lag at low revs - again, completely normal.

I press throtle and it goes to 1500 rpm and without moving my foot from a pedal it just goes back to 1300 rpm followed by stuttering.

If I do it very carefully without pressing gas pedal hard, it won't happen. 

11 minutes ago, Octavia2019 said:

I press throtle and it goes to 1500 rpm and without moving my foot from a pedal it just goes back to 1300 rpm followed by stuttering.

If I do it very carefully without pressing gas pedal hard, it won't happen. 

 Take a look at this video, I tried to cut and slow down a bit so you can see better.

@Octavia2019   Welcome.

So a 1.5 TSI ACT.   ACT being the kind of important bit.    Sorry no idea what is wrong. 

 

What country are you in, and is it E5 95 ron min petrol you get?

Have you had the car from new or only recently?

Were those new spark plugs only put in recently?  & did you put them in? 

 

???

Before you got the car had anyone changed the Cam Belt?

..................

The DSG clutch slipping is not unheard off.  CAUSING THE RPM TO RISE, NOT DROP.

The was a Software Update on some earlier than your vehicles and earlier still there were upgraded clutch packs being fitted,

Edited 5 January, 20251 yr by Ootohere

52 minutes ago, Ootohere said:

@Octavia2019   Welcome.

So a 1.5 TSI ACT.   ACT being the kind of important bit.    Sorry no idea what is wrong. 

 

What country are you in, and is it E5 95 ron min petrol you get?

Have you had the car from new or only recently?

Were those new spark plugs only put in recently?  & did you put them in? 

 

???

Before you got the car had anyone changed the Cam Belt?

..................

The DSG clutch slipping is not unheard off.  CAUSING THE RPM TO RISE, NOT DROP.

The was a Software Update on some earlier than your vehicles and earlier still there were upgraded clutch packs being fitted,

I have car since March '24 and Bosch spark plugs are fitted 2 months ago together with oil and filter change. Cam belt is not changed, it has only 110.000 km, is it too early? 

I have half a tank, and definetly will try to put most quality fuel on market in my country (Bosnia). 

 

Also, I think that some ECU update or reset can help since there is no anything on diagnostics.

Yes it is too early for the cam belt,

but in the UK up to last July the SKODA / VW Recommendation was at 5 years / 50,000 miles and people had them done.  Some by less than competent people.

4 minutes ago, Ootohere said:

Yes it is too early for the cam belt,

but in the UK up to last July the SKODA / VW Recommendation was at 5 years / 50,000 miles and people had them done.  Some by less than competent people.

My concerns are mostly if this continues, will it make more damage to a car. 

Driving up a very steep hill is a trouble, and car is doing this 3-4 times. 

 

The RPM is not dropping, if it did drop that fast you would be thrown forward against the seatbelt.

 

The indicated rpm is dropping on the rev counter at the same time as a stutter or misfire, likely to be an ignition fault given the erratic tachometer.

5 minutes ago, J.R. said:

The RPM is not dropping, if it did drop that fast you would be thrown forward against the seatbelt.

 

The indicated rpm is dropping on the rev counter at the same time as a stutter or misfire, likely to be an ignition fault given the erratic tachometer.

What can cause misfire? 

Spark plugs, ignition coil, injectors, car battery... everything changed and checked in the last two months.

Well, first things first. A scan is needed. If it is a problem then it will be recorded. Otherwise the only other thing I can think of is something to do with the ACT system bringing in the rest of the cylinders and there being a momentary lowing of revs to bring all the cylinder ignition timing into sync.

7 minutes ago, varaderoguy said:

Well, first things first. A scan is needed. If it is a problem then it will be recorded. Otherwise the only other thing I can think of is something to do with the ACT system bringing in the rest of the cylinders and there being a momentary lowing of revs to bring all the cylinder ignition timing into sync.

Scan showed misfire on multiple cylindres in the moment when this happens. 

Can ACT be turned off without causing problems to engine? 

Nope....ACT isn't the issue...and it's the technology built into the engine to drop cylinders when load is lower.

 

Getting back to the misfire, obviously worrying. What manufacturer did you use for the sparkplugs and ignition coils? If it's not Bosch or Skoda OE, then that is a good first port of call. There are so many questionable parts out there and VAG csrs are picky about their parts! Please also check the earth contacts for the coils as they can break if put in incorrectly or overly tightened or are too loose. Also check for corrosion on the earthing points too.

 

Are you getting any other ignition based faults or any timing faults?

 

 

13 minutes ago, varaderoguy said:

Nope....ACT isn't the issue...and it's the technology built into the engine to drop cylinders when load is lower.

 

Getting back to the misfire, obviously worrying. What manufacturer did you use for the sparkplugs and ignition coils? If it's not Bosch or Skoda OE, then that is a good first port of call. There are so many questionable parts out there and VAG csrs are picky about their parts! Please also check the earth contacts for the coils as they can break if put in incorrectly or overly tightened or are too loose. Also check for corrosion on the earthing points too.

 

Are you getting any other ignition based faults or any timing faults?

 

 

It's Bosch.

 

No, nothing else except this issue. I will check those definetly.

There are many snide parts available on the packaging that looks right.  Spark Plugs especially.

?

What spark plugs were fitted, and even though pre-gapped was that gap checked on all 4 plugs before fitting? 

 

Is the Air Filter is a nice clean and dry condition? 

11 minutes ago, Ootohere said:

There are many snide parts available on the packaging that looks right.  Spark Plugs especially.

?

What spark plugs were fitted, and even though pre-gapped was that gap checked on all 4 plugs before fitting? 

 

Is the Air Filter is a nice clean and dry condition? 

Bosch spark plugs fitted and after a month mechanic switched to some other to check if the problem is there and no difference. Ignition coils same story. Car is behaving exactly the same.

 

Air filter is MANN fitted two months ago. 

 

Maybe it can help to trace a solution that the problem is more "vissible" when its cold and wet weather. 

The only other thing I can think of - is that the MAF sensor might be playing up and incorrectly detecting the Air / fuel ratio mix.  However, if there was a problem here, I would expect a code or lean code.

This is just something to consider but I can not tell if this is the case or if this is related. VAGs with DSGs slip the clutch on second gear at low speeds instead of downshifing to first gear. It might just be that it is purposelly slipping the clutch and the rpm decreases when you accelerate and the clutch is properly engaged.

I tried to duplicate this today with my car, 2.0 tdi dsg, but could not get such rpm drop happen. Rpm stayed the same and only velocity changed while the clutch was slipping.

 

However, it might be related to the slipping feature if it only happens on second gear. Perhaps the clutch is wearing out?

Does it make any difference which driving mode you're in?

On 05/01/2025 at 13:43, Octavia2019 said:

Hi guys, do you know what can cause this slight loss of rpm when accelerating with my Octavia 1.5 tsi dsg? 

It's happening only when I press hard on gas pedal on low speeds. No errors on dashboard. Car is working perfectly in every other circumstances.

Car has 110.000 km and new spark plugs, car battery, engine block breather and checked fuel injectors which are fine.

Is this something about DSG? 

 

You cannot be pressing hard on the accelerator if the upshifts are happening at 2000 rpm.

Forgot that i started this topic. So update: almost 3 months no issues but it started again after couple days of heavy rain. I'm now sure that is somehow causing problem. Is there possibility that water or moisture is accumulating somewhere around engine?

On 05/01/2025 at 12:43, Octavia2019 said:

Hi guys, do you know what can cause this slight loss of rpm when accelerating with my Octavia 1.5 tsi dsg? 

It's happening only when I press hard on gas pedal on low speeds. No errors on dashboard. Car is working perfectly in every other circumstances.

Car has 110.000 km and new spark plugs, car battery, engine block breather and checked fuel injectors which are fine.

Is this something about DSG? 

I can't even see the video, there is the black box where it should be but nothing is working.