what is the reason behind air pump removal?

[slater1982]

Ok,
 
 As per the title, im not exactly sure what this afore mentioned air pump does or the reasoning behind its removal, although i do know there\'s a sticker on it that says "DO NOT REMOVE AIR PUMP" ?? :3Confused  Also, are there any dangers of doing this, seen somewhere on here about it causing problems with the water pump???
 
 
 Sorry if i seem a little dense with this question,
 
  Thanx guys

[Brett]

Unless you are upgrading to a new exhaust system that does away with the co-axial air and reburning system, then there is no real benefit. Removing it on an otherwise stock vehicle (assuming you had blocked off the air control system etc) would result in a lot of unburnt hydro carbons... On mater cars it would probably murder the CAT quite quickly too.

[slater1982]

think i\'ll not be doing that then, think furthest i\'lll go for now would be cat back exhaust,so i guess thats ok?? (cant afford the new ecu to go with full system!!)

[Prof]

The airpump feeds the seconday air system.  The air it pumps goes to one of three places - a lot of the time it goes out through a silencer under the drivers headlight.  On startup and deceleration it feeds air into the exhaust to help feed the cat with air and reduce afterburn and initially to heat up the cat - if you\'ve no cat it won\'t be doing this.
 
On idle the air control valve directs the air pump air through the lower inlet manifold through a one way valve into the exhaust port sleeves - this is to reduce emissions on idle (it\'s what gets you through the MOT
 
If you remove it, it\'s advisable to go with an idler pulley or a double alternator pulley, as the water pump can slip with only part of a single belt making contact - but aside from that and some higher emissions - it does no harm when / if you\'ve decatted.

[slater1982]

ok thanks then guys, much appreciated. will def be leaving it on (certainly for a fair old while at least anyways!!)

[m1tch]

Im still running my air pump, no real issue with it until you need more space for a larger turbo really, my CO % is 0.18, im allowed 3.5% lol emissions pass FTW