Cold start exhaust leak;

[GTI-Guy]

I've got a 7.5 performance with PPF/GPF & have an exhaust (or manifold or something else) leak.

It's guaranteed to be there on cold start up to around 1800RPM (never over 1800) & dissapears when cold start idle revs drop to normal, it's occasionaly present on warm start, but never on hot. I've had a dealership & independant look at it & both said the exhaust look fine & has no leaks, although it just sounds like a regular "fut, fut" exhaust leak.

My 1st though was that that it might be EGR related as it's present generaly when an EGR valve would be active, but as far as I know EGR duties are carried out by B-Cycle & valve timing on this engine. I'm a bit concerned that the source may be more involved (expensive) than a simple exhaust leak & I'm starting to wonder about manifolds & what not.


Any ideas appreciated.

[willni]

What year 7.5?

Sounds more like the GPF is doing a regen.

[GTI-Guy]

It's an early 2019 with about 20K.

Unless it's running regen every cold / warm start & a regen sounds just like a blown exhaust I doubt its regen. Does this GPF run a regen cycle as such or it it just continuous due to heat from normal running?

[Talk-torque]

Has it always done this, or has it developed since you got the car?

[SRGTD]

What year 7.5?

Sounds more like the GPF is doing a regen.

I’m not sure it’s doing a regen - I think this might only happen when the engine’s hot enough to burn off any accumulated soot deposits in the GPF and the symptoms the OP has described are always present on a cold engine and never when hot.

The current model Polo GTI has VW’s 2.0 EA888 Gen3b engine (I think the Golf GTI has the Gen3 version) and the symptoms that owners have experienced during an active GPF regen are all or some of the following;

- Louder, deeper exhaust note
- Increased fuel consumption during the regen
- A slight hesitancy or lumpiness of the engine
- A ‘hot’ smell.

[madstaff]

I’m not sure it’s doing a regen - I think this might only happen when the engine’s hot enough to burn off any accumulated soot deposits in the GPF and the symptoms the OP has described are always present on a cold engine and never when hot.

The current model Polo GTI has VW’s 2.0 EA888 Gen3b engine (I think the Golf GTI has the Gen3 version) and the symptoms that owners have experienced during an active GPF regen are all or some of the following;

- Louder, deeper exhaust note
- Increased fuel consumption during the regen
- A slight hesitancy or lumpiness of the engine
- A ‘hot’ smell.

Agree with all that, doubt it's doing a regeneration from cold, certain conditions have to be met and a minimum temp has to be achieved before a regeneration is triggered.

I would be taking it to another garage for a 2nd opinion if you think its an exhaust leak.

[GTI-Guy]

Has it always done this, or has it developed since you got the car?

Don't really know, the wife used the car for the 1st year & it was only really noticed when I got it as a hand me down.

It's not regen.


Does anyone know how cold start is handled on Gen3? I went off on a tangent thinking its was a leaking secondary air injection valve at the exhaust end, but I don't see any plumbing coming from the air box, so it doesn't look like it has this.

Edit- now I'm not sure if it's Gen3 or 3b - It's a DKTB engine with no MAF sensor or secondary air injection, so I guess its Gen3, not 3b.


Thanks all.