Had Pre-Cat removed, milltek now QUIETER?!

[john87]

I picked up the car yesterday after having the pre-cat removal mod done, and to my surprise the milltek non-res (which was sounding pretty good beforehand) now seems almost as quiet as standard! 

Can anyone explain how this has happened as it's baffled me (pardon the pun) 

[jedi-knight83]

perhaps it was actually blowing a bit on one of the joints and when they put it back together its now sealed?

Mine made my non res miltek a fraction louder and DSG changes popped a bit more.

[john87]

Hmm I'm sure it was all put together fine, when standing behind the car with the engine idling, the sound coming from the tailpipes is noticeably more muted - could it have been that the pre-cat was actually amplifying the sound?

[TrickGTI]

They havnt nicked your no res pipe have they and fitted a standard one 

[john87]

They havnt nicked your no res pipe have they and fitted a standard one 

I did actually check this once I got home  no it's all still there thankfully...

The problem goes further than a quiet exhaust however, on the drive home tonight I gave it some welly and was frightfully disappointed at the result  so much so that I'd say that the car feels like its lost the equivalent of the stage 1 map! I'm also getting a high-pitched whine which increases proportionally with engine revs, which wasn't there before. I'm supposed to be taking part in a rolling road day in two weeks (where I've had a session before and achieved 251bhp) so all will become clear then, and I'll hook it up to the VCDS while I'm there, see what error codes pop up.

So all in all, not quite what I was expecting 

[john87]

Engine management light came on today on way home from work  and promptly hooked it up to VCDS which came back with "Catalyst System Efficiency Below Threshold (Bank 1)"

The garage's opinion was that given the muted exhaust note and lack of performance after the fault was cleared, they were sure the exhaust was blocked somewhere; most likely the bend after the pre-cat.

I contacted the garage who removed the pre-cat who said they were 100% sure nothing was left in the exhaust, however I'm not so confident myself so I'm going to get it stripped down again and hope to find something stuck there!

Any thoughts on this?

[Andy_Ed30]

Engine management light came on today on way home from work  and promptly hooked it up to VCDS which came back with "Catalyst System Efficiency Below Threshold (Bank 1)"

The garage's opinion was that given the muted exhaust note and lack of performance after the fault was cleared, they were sure the exhaust was blocked somewhere; most likely the bend after the pre-cat.

I contacted the garage who removed the pre-cat who said they were 100% sure nothing was left in the exhaust, however I'm not so confident myself so I'm going to get it stripped down again and hope to find something stuck there!

Any thoughts on this?

Sounds like they have let some of the pre-cat fall down to the cat.

[TrickGTI]

This is a real head scratcher with everything thats going on with it! Keep us all posted on what is found!

[john87]

Engine light came back on today when I attempted an overtake manoeuvre, not a good idea! Felt like a 1 litre  exhaust quieter than standard now, and this is a milltek non-res we're talking about...

Its going back on Monday to the garage that done the pre-cat removal, to take the whole exhaust off and find out what the hell's going on!

[donovan2123]

Could be a sensor issue maybe?

[john87]

that's what I first thought, but even after the fault code was deleted, the car continued to drive poorly immediately afterwards. Quieter exhaust lead us to believe the exhaust was blocked though as if the pre or post-cat sensor had failed or was reading high, the car would still have normal power.

[JMP]

If they removed the precat ok, they might have handled your downpipe too hard and messed up your main cat somehow. This might explain the DTC and low perf.

[john87]

If they removed the precat ok, they might have handled your downpipe too hard and messed up your main cat somehow. This might explain the DTC and low perf.

They told me over the phone that they removed all contents of the precat with no issues and even showed me the contents when I went back, however they phoned me back later that day and said they're going to strip it down and check for blockages as they 'have a few ideas'  engine light is back on, so either cat is mullered or blockage is causing an inconsistency with lambda readings. I'd put my money on the second one as it would explain the quiet exhaust

[john87]

...so after having the exhaust off the car a total of three times, we've came to the conclusion that the main cat is now blocked  as although the car seems to run a lot better, the exhaust note is much quieter than before I had the work carried out and I keep seeing the 'Catalyst System efficiency below threshold (bank 1)' appearing every other day.

The garage who carried out the initial work have apologised several times and have suggested an idea which has got me thinking  they have offered to cover the cost of a 200 cell sports cat and all I have to pay for is the manufacture and fitting of the custom pipework (around £80 they tell me) which I think is pretty decent of them, the only catch being that I'd have to then find somewhere that would perform a stage 2 map, decisions decisions!

So the question to you all is now, does anyone have a recommendation for a VAG tuner in Scotland that could facilitate the Stage 2 map and rolling road session? I've got a few places written down but would appreciate any experiences you guys may have had 

[PDT]

You won't absolutely need a stg2 map, just the cat light mapping out. If you fancy a drive I can Dyno test it and map out the cat light for £50. (Newcastle area)