B7 ‘cold start’ / noise change

[Fatneck73]

Hi all

When i start the car, It ticks over at c1400rpm x 60 seconds or so...and then calms down. I believe this is called ‘cold start’. No probs.

What i cant understand is that if i then rev it back to 1400rpm, the noise is nowhere near as ‘deep’. And before you say it, then backbox valves are disconnected.

Soo...whats changing? Are there more valves earlier in the zorst or something else...coz i wanna disable it...sounds awesome when on cold start.

TIA

Ade

[coffey555]

It is the SAI pump forcing more air into the engine to warm up the pre-cats quickly. Pretty sure it injects more fuel as well to match the increased airflow.

It does sound nice but is a bit loud if you have the centre resonators deleted (in my case, with straight pipes) with the exhaust valves open.

Nothing you can do to get that deeper sound when reving the engine at a standstill. However, you will get it when the engine is working under load (high gear, low revs etc).

[Fatneck73]

Yep, im ‘straight pipes’ as well

Brill answer, thats very much.