What is an AIR injection pump???

[ADY1983]

Hi Can someone please tell me what an air injection pump is, what it does and do I need it?? on a W124 300-24. see pics below...

 

[Bobby Dazzler]

I believe it's part of the emmissions control system, and injects air into the exhaust to help out the catalysts after a cold-start. At least that's what they apparently do on my car!!

Does your car have catalysts?

 

[andy_k]

as above, it purges the cats of any unburnt fuel etc from startup.

If you've got cats you need it

Andy

 

[big x]

It works like a jet afterburner.In this case air not fuel is pumped into the exhaust gases super heating them so the cat starts to work a bit quicker.On my E320 you can hear it run for the first couple of minutes before disconnecting. I hate them as they add weight and even when off there must be additional friction on the pulley belt. Add in the environmental cost to make them and I bet it's a zero sum game pollution wise.They are required by law in places Switzerland.

Along with the aircon pump and various sensors I see it's another Jap made part.

adam

 

[big x]

Hi Can someone please tell me what an air injection pump is, what it does and do I need it?? on a W124 300-24.

Did you put it back on Adrian, or manage to run the car without it ?

adam

 

[Doodle]

Certainly on our SL, you CAN remove it, blank off the air hoses etc etc, but you then need to fit a slave pulley and bracket in its place to maintain the belt run.

Fine if the engine is coming out anyway, an absolute pig to do with the engine in place (on the R129 anyway)

We had to replace ours a while back due to the pulley bearing failing.

 

[ADY1983]

Hi
I haven't really driven the car much, but I have been running the car fine without the pump, I used a shorter belt as I had no need for the air con pump either. The car is in the garage today having a full stainless system with a remus back box minus the CAT as the the car is an 88..

Cheers

 

[Dieselman]

Doesn't the air pump also fool the Lambda sensor so it sees a weak mixture thus increasing the mixture strength for cold starts?

 

[Doodle]

Not 100% on that one, but I'm not sure it does.

The pump doesn't actually start doing anything until the engine is running, as it is powered from the serpentine belt.

In addition we got the same response from both the dealer and a trusted friend who is an engineer at DCUK, that the pump can be removed without problems, as it is there merely to assist startup emissions.

It has to be replaced by a pulley and bracket to maintain the belt run, and the extra labour involved in changing the parts over to do this makes it nearly as expensive as replacing the pump itself, however

 

[big x]

The bearings on these pumps seem to whine and seize with some regularity.The Japanese just don't engineer these things for long life spans IMHO.

adam

 

[Birdman]

If it accelerates the heating of the catalyst on cold starts and the catalyser suffers most stress during the cold start phase, then removing the injector will shorten the life of the catalyst. So why do it (unless my concern is unfounded)?

 

[big x]

If it accelerates the heating of the catalyst on cold starts and the catalyser suffers most stress during the cold start phase, then removing the injector will shorten the life of the catalyst. So why do it (unless my concern is unfounded)?

You don't need a cat on a pre-August 92 car, however it has to be said even though you might be right my 1997 C180 does not have an air pump nor do most other mid size engines of that era AFAIK.

adam

 

[Bobby Dazzler]

You don't need a cat on a pre-August 92 car, however it has to be said even though you might be right my 1997 C180 does not have an air pump nor do most other mid size engines of that era AFAIK.

I once read somewhere that it's only there to comply with US emmissions regulations, and so if that is indeed the case, might only be fitted on engines that are sold in the US?

 

[Birdman]

....my 1997 C180 does not have an air pump nor do most other mid size engines of that era AFAIK.

adam

Ah'm reet glad ta hear't! (Btw does that include over-engined cars of this era?? )

 

[Glenn Smith]

Air pump is there to speed up heating of cats and lambda sensors, usually if you don,t have one you have a lambda sensor with three wires instead of two and these have heaters in them, technicaly you could run without it but may have running problems untill the lambdas have warmed up.

 

[Glenn Smith]

Doesn't the air pump also fool the Lambda sensor so it sees a weak mixture thus increasing the mixture strength for cold starts?

lambdas don't work untill hot anyway

 

[jazzdude]

Hi Can someone please tell me what an air injection pump is, what it does and do I need it?? on a W124 300-24. see pics below...

On the left side of the first image and the bottom left of the second, there is a hole which seems to suck air into the pump. Should this be open like this or is there a hose or a cap on this. On my car, it is just open as it is here and it sounds like a hole in an exhaust when the pump is working. Is there another part missing?

 

[carat 3.6]

On the left side of the first image and the bottom left of the second, there is a hole which seems to suck air into the pump. Should this be open like this or is there a hose or a cap on this. On my car, it is just open as it is here and it sounds like a hole in an exhaust when the pump is working. Is there another part missing?

There is a cap that fit's over that hole, but even with it fitted the pump is still very noisey.

 

[jazzdude]

There is a cap that fit's over that hole, but even with it fitted the pump is still very noisey.

Do you know whether it is part of the pump or a separate part?

 

[markjay]

During my Vauxhall Omega forum days, the advice from those in the know was to simply disconnect the pump if it became noisy rather than replace it.