Air pump - everything you wanted to know...

Prof · May 04, 2007, 09:49:47 PM

On the FC, the removal of the air pump means that some of the unmetered air that was coming in through the air pump is no longer there, and so the fuelling at idle is a little rich and the car could run poorly. The solution on the FC is to adjust a small bypass valve on the air meter, which allows a given quantity of unmetered air to pass. This is normally blanked off, as it\'s set at the factory, but you can remove the plastic cover bung, and get to the adjust screw.

I would guess that you need to do something similar on the FD - either adjust fuelling on the Apexi to cater for the loss of some air, or allow air bypass through/around the AFM.

Brett · May 05, 2007, 12:56:43 AM

On the FD the air pump is switched so it only works below 2500rpm (IIRC) the air pumps on the 2nd gens are running all the time, so the same techniques do not apply accross the board I\'m afraid.

Prof · May 05, 2007, 09:37:29 AM

Quote from: BrettOn the FD the air pump is switched so it only works below 2500rpm (IIRC) the air pumps on the 2nd gens are running all the time, so the same techniques do not apply accross the board I\'m afraid.

Running all the time yes, but the ACV switches where the air goes depending on Revs, so in that respect it is similar (air goes to one of 3 places, into the intake, into the cat or into the silencer pipe under the front headlight). At idle, some air is fed into the intake.

sparkgap · May 05, 2007, 01:45:29 PM

Quote from: ProfOn the FC, the removal of the air pump means that some of the unmetered air that was coming in through the air pump is no longer there, and so the fuelling at idle is a little rich and the car could run poorly. The solution on the FC is to adjust a small bypass valve on the air meter, which allows a given quantity of unmetered air to pass. This is normally blanked off, as it\'s set at the factory, but you can remove the plastic cover bung, and get to the adjust screw.

I would guess that you need to do something similar on the FD - either adjust fuelling on the Apexi to cater for the loss of some air, or allow air bypass through/around the AFM.

The FD doesn\'t have an AFM but your comments led me in the right direction.
I unscrewed the air bleed screw about 2 turns under the throttle body and it\'s idling sweet and even without the air pump now.
Thanks Prof.

Matts-gen2 · August 15, 2007, 01:50:03 PM

Can you tell me exactly where this afm bypass valve is please? Unbolted the air box and lifted it up to look on the underside of the afm (pressuming im right in thinking this is the metal block before the intake pipe), and couldnt see anything.

Secondly, been reading up on after removal of the air pump the secondary ports ( or 5th & 6th ports ), are no longer activated because it was the air pump that activated them.

How are you meant to make them open now? electronically or using a cable system?

Has anyone done this???

Thanks,

Matt

pjd7325 · October 18, 2007, 07:20:48 AM

So what benefit does removing the air pump actually have? Does it increase bhp?

Matts-gen2 · October 18, 2007, 09:39:15 AM

It removes excess drain from the engine, all belts to power steering pumps, A/C etc are extra items for the engine to run.

When i got my car the air pump was gone already, but imagine it felt a bit more free once it was taken off.

what hadnt been done is the thermal reactor / heat exchange hadnt been taken off. this is a box in the exhaust after downpipe, it uses an air supply from air pump. the idea is it cools down exhaust gases before emmiting them into the atmosphere.

mine was blowing on a flange, so had the box cut out and a straight pipe welded in.

assuming yours is the same, and you havent got any cats anywhere, this can be removed and i found does free up the car a bit. this must have some gain i imagine 10 -15 BHP.

you will have to get a dual alternator pulley, and double up the alternator belts, to keep the required tension on the water pump pulley (at the bottom).

Im sure another member on here will tell you about blocking off the air pipes from air pump removal aswell. mine was already done so i cant be certain what needs blocking off.

pjd7325 · October 18, 2007, 02:20:05 PM

I think for the hassle of removing it etc I might as well leave it on. I don\'t have air con either. Surely if they cause that much of strain on the engine Mazda wouldn\'t of installed one in the first place!:) But that\'s only my opinion.

rico2k_uk · October 18, 2007, 05:17:16 PM

its not so much strain, its just extra strain that isnt realy needed especially with a couple of exhaust mods. when my blanking plate and belt come through, that bad boy is going in the shed

sparkgap · October 18, 2007, 08:11:49 PM

Quote from: pjd7325Surely if they cause that much of strain on the engine Mazda wouldn\'t of installed one in the first place

It helps burn off the horrendous pollution in the exhaust that the wankel produces.
Since I did away with my cat, the air pump just made the car backfire loudly everytime I lifted off the throttle, even in traffic. So I have disconnected the electrical plug to disable it. Idle is not as smooth without the pump but raising the idle speed to 1000 and opening up the bleed screw has helped. I daresay a bit more PFC map fiddling would sort it out at normal idle RPM.

pjd7325 · October 19, 2007, 06:56:54 AM

Quote from: sparkgapIt helps burn off the horrendous pollution in the exhaust that the wankel produces.
Since I did away with my cat, the air pump just made the car backfire loudly everytime I lifted off the throttle, even in traffic. So I have disconnected the electrical plug to disable it. Idle is not as smooth without the pump but raising the idle speed to 1000 and opening up the bleed screw has helped. I daresay a bit more PFC map fiddling would sort it out at normal idle RPM.

:Laugh I bet that\'s all the un burnt fuel setting fire in the exhausts! Entertaining though I bet. I\'m going to leave mine on I think it\'s not doing any harm as I don\'t use my car for track days etc. Just my everyday car. Going off the subject.... someone came up to me while filling with petrol and asked what porsche I was driving! I sarcasitly pointed out what it said on the back!:Laugh

Matts-gen2 · October 19, 2007, 09:53:12 AM

I dont use mine for track ,well not yet, i definately saw an improvement when i took the thermal reactor off.

haha, i havent been asked that but the porsche 924 does look similar.

sparkgap · November 30, 2007, 08:06:26 PM

Kind of a double edged sword with the air pump, just took the RX to the local garage and said "I think you\'ll have to look it up". He failed it even though WGT\'s recommended MOT station passed it less than 6000 miles ago. 6 on the CO instead of 4 minimum.
I\'ll take it back tomorrow and reconnect the air pump first and if that doesnt do it then i\'ll try the test setting on the PFC for the injectors to lean it out temporarily.

doddy · December 20, 2007, 12:39:31 PM

My TII exhaust is standard but for decat pipe welded in and stainless cans.
The exhaust shop welded the Air Pump feed into the decat pipe.

Sorry if this has been covered in the thread, but does the Air Pump pump into the \'cat\' at idle? If not can I fool it into doing so? I like the idea of diluting the exhaust fumes at idle!

I\'m not bothered about removing the pump just want an MOT pass at this stage.

Prof · December 20, 2007, 01:28:58 PM

Quote from: doddySorry if this has been covered in the thread, but does the Air Pump pump into the \'cat\' at idle? If not can I fool it into doing so? I like the idea of diluting the exhaust fumes at idle!

It does - one of the side effects of removing the air pump means you have to play fiddle and tune before MOT day to get through the CO/HC test - you can normally pass one of the tests but both is tricky.

I\'m figuring on cutting some fuel for idle using the eManage, it may run lumpy, but normal service is just a dip switch away :cool