Louder exhaust and another random noise

[funkyg]

2020 Polo GTI+ 18k miles.
I’ve had more grief in the last six months with this car than the last ten years with my last car!

The other day I dropped the missus off at work and we both noticed that the exhaust seemed louder than usual. My first thought was just a blowing exhaust, no big deal. On driving home I turned the radio off to listen closer and noticed another noise that I can’t quite put my finger on.
At first I thought it might be a dragging brake, however I put the car in eco mode and allowed it to coast the car didn’t really slow down as if the brakes were on.
I then noticed the additional sound only occurred when accelerating/under boost. I don’t know if it’s just in my head but I think the acceleration seemed slightly diminished as well, not bad just not quite as spritely as usual. Leaky turbo hose maybe? Slipping DSG clutch?

I know it’s tough to diagnose remotely I just wondered if anyone had any ideas until I can ring the dealers tomorrow? Cheers.

[PO10ASH]

OPF regen was my first thought but then you stated another random noise which threw me off. Have you done a car walk around, all leads to the exhaust and nothing under the bonnet?

[SRGTD]

@funkyg; Agree with @PO10ASH re. OPF regeneration; a louder exhaust note is one of the tell-tale signs. Other tell-tale signs (you might not notice them all) are;

• slight hesitancy under acceleration and engine idle lumpiness (the fact you experienced this does seem to confirm an OPF / GPF regeneration)

• engine fan running

• stop start doesn’t work

• a ‘hot’ smell

• significant worsening in fuel consumption during the OPF regen process

Have a look through the discussion thread at the link below. I’ve posted details of symptoms experienced during a couple of OPF regens in my car in that discussion thread.

https://www.uk-polos.net/viewtopic.php?t=73177

Be aware that if a GPF regeneration is still in progress when you reach your destination and turn off the engine, it will recommence during your next journey so it can complete the process. When I’m aware a regen is in progress in my car, I’ll try to ensure it completes before I reach my destination and switch off the engine, even if it means I have to extend my journey distance / time.

The second issue / noise could be totally unrelated to the above. If it was your brakes were binding / dragging, then there would’ve been heat build up too, and you probably would’ve noticed the wheel on the corner of the car where the binding brake was would feel warm / hot to the touch.

Please update this discussion thread for the benefit of other forum members once you’ve established what the second issue is / was.

[funkyg]

Thanks guys, this really sets my mind at rest.
The symptoms listed by SRGTD sound very much like what I’d been experiencing. I didn’t notice the smell but the missus did, and I had noticed a drop in mpg that I hadn’t mentioned. I also noticed the stop/start system hadn’t been cutting the engine out when stopped.

As for the sticking brake I think that was a red herring, as after my last drive I did feel each wheel to see if and had got hot and none were. It’s just what my first thought was.

I wish I’d known all this before yesterday, I had a couple of longer drives yesterday and today and asked the missus if we could use her car instead until I could get my car checked out. A) these would have been perfect for clearing the OPF and B) her car is awful! It’s a ten year old 1.2 Hyundai i20.

I’m going to take the car out tomorrow for a blast along the dual carriageway, plus I also have another long drive to do at the weekend (which will now be in my car instead of the missus’). I’ll monitor how everything turns out and will update the thread as requested.

I thought I’d got away from all this after switching from diesel to petrol!

[SRGTD]

@funky; the following are the guidelines in some VAG owners manuals for petrol engined cars 2.0 litres and above with a GPF / OPF to help burn off soot accumulations in the filter if it becomes clogged up;

Accelerate to around 60 mph and change down a gear. Remove your foot completely from the accelerator so the car decelerates under its own steam. Accelerate back up to 60 mph and repeat the process a few times.

Removing your foot off the accelerator as above helps to draw air / oxygen into the exhaust system as the car decelerates, and the extra air / oxygen aids the process of burning off any soot accumulation in the particulate filter. I carry out this process periodically in my car on longer journeys to (hopefully) help reduce soot build up. I tend to change down to fifth gear (I use the steering wheel paddles) then accelerate up to around 3,500 - 4,000 rpm and remove my foot off the accelerator to let the car decelerate (don’t apply the brakes). I repeat this process usually around 6-7 times. I also use this process (if road / traffic conditions permit) while the car is actually going through a GPF regeneration as it seems to help speed up the regeneration process.

[funkyg]

Problem solved, purring like a kitten again. Moral of the story…drive it harder/longer/more often!

Thanks again.

[SRGTD]

Problem solved, purring like a kitten again. Moral of the story…drive it harder/longer/more often!

Thanks again.

Good to hear it’s sorted .

From an owner’s perspective, it would be useful if the dealership spent a little time at handover of a (new or used) car to the customer explaining the symptoms of the GPF / OPF regeneration process. I’ve seen quite a few posts on some of the other VAG forums where owners have been concerned by the ‘tell-tale’ signs of a regen, thinking there’s something wrong with the car, when what they’re experiencing is perfectly normal and nothing to be worried about. It would also be useful if there was some sort of indicator on the instrument panel that illuminated when a regeneration was happening.