Partially blocked exhaust?!?

[littleg]

I had a resonated after market exhaust (Milltek) fitted about 6 months ago, and started hearing occasional dull popping/knocking noise when engine cold. Feels like the exhaust is getting slightly blocked then clearing itself.

The noise became a bit more frequent, until this morning when it just about stalled for a few seconds, felt like the exhaust was almost blocked - dropping the clutch and revving the engine seemed to clear it, and I parked it up shortly after.

Wondering if the secondary cat might have collapsed and be rattling around, and considering just taking into local kwikfit for them to have a look.

Anyone had anything similar?

 

[littleg78]

Randomly posted the above from a really old profile I’d forgotten about! Watching the thread from my proper account now - any help or advice appreciated!

 

[littleg78]

Chap at Kwikfit found a loose clamp on the engine side of the cat, so replaced it and had a quick look at cat which was normal. Might explain the knocking noise, but doesn’t really help with the occasional blockage feeling. He put a new clamp on and I’ll have to wait and see if any better.

 

[Elviic]

Not driving hard enough if you’re having a blockage?

 

[DS197]

Have you had it plugged into Clip or a generic OBD reader?

 

[littleg78]

I got the blocked exhaust feeling again this afternoon, just after pulling off the drive, but this time it was a bit more dramatic!!!

It felt a bit like the usual stuttering (partially blocking and clearing), then it felt like it was blocked, then there was a massive bang from underneath the car, and it was gone!

The bang sounded like it came from either the middle or the front of the underside of the car. I stuck an OBD2 reader on the car and there are no fault codes. Car seems to be driving normally, and no leaks anywhere that I can see.

It doesn't happen that often, but I'd like to get to the bottom of it, specially after today! What's going on???

 

[RSRowe]

Does it do it normally when it’s cold or warm?
Mine runs like a bag of shit when manoeuvring it from cold. Just kinda put it down to being one of them quirks

 

[littleg78]

I’ve only really noticed it when it’s cold - first mile or so, and even then it’s only sometimes, sounds a bit like heavily muffled pops and bangs... appart from today when there was a noise like a gun going off!

It runs super smooth apart from that, steady idle, no kangaroo hoping down the road! It’s just that momentary total loss of power that freaks me out - like it’s blocked or cut out.

I might just keep swapping out exhaust bits until I get to the engine - sports cat and manifold next...which is expensive if they’re not causing the problem!

 

[RSRowe]

It sounds exactly what mines like. It’s almost to the point when I’m reversing out the garage that it’s going to cut out.

If your cat had collapsed I feel like your issue would be constant.