Silver88GXL

Well, the subject says it all. Does anyone know when air is injected to the cat? Deceleration? Acceleration? below 3000rpm?

Thanks

Carl

j9fd3s

iTrader: (3)

the book says 5th gear cruising

mike

Silver88GXL

If it is only injecting it while cruising in 5th, then at what point does the cat start to break down without the air pump?

I am asking because I am trying to findout how long my cat might last without the injection pipe.

Thanks

Carl

Mark S

iTrader: (1)

Not long. It'll clog up in a couple weeks.

tomaszjc7

The only reason the air pump is there is to blow air intop the cat at idle and low rpm, 3000 and down. This is because exhaust fumes will clogg the cat without the air pump at low rpm. You can eventually remove the air pump to make the bay look nicer but only iff you have a down pipe. I really dont know how long you'll last with the air pump dissabled but, its only considered a TEMPORARY FIX... So dont keep it off.

j9fd3s

iTrader: (3)

when the car is warm the air pump goes like this
idle to 1750-2500rpm air is injected into the exhaust ports
2500 and up air is vented back to the air cleaner/ atmosphere
cruising in 5th air is sent directly to the cat

mike

PaulC

I actually rigged mine on my 87 (R.I.P.) to runn all the time. it significantly reduced my emissions underload, and Im not sure why that was either. But I still had to replace the cat to pass.

Scott 89t2

the cat will last longer with NO airpump.... I'm installing a cat this week and I'm going to remove the airpump first. the cat melts from heat. heat is caused by burning. the air being injected in is what burns...

of course it won't do very much emmisions wise with no air pump though . but not as loud.

HAILERS

Sitting in your driveway, with the engine fully warmed up, there is no air going to the Split Air pipe. But there is air going to the cat from the air pump thru the Port Air passage in the acv(see attached jpg). That Port Air makes its way to the exaust port diffusers and mixes with the exaust going to the cat.
When driving the car, the Split Air solenoid is energized and opens to send air thru the split air pipe to the cat.
When driving the car at say 70mph(and lesser speeds and higher speeds) the switching solenoid is energized closed, which makes the switching diaphram in the acv(see attached jpg) spring load to close the port air passage and at the same time open a passage to the split air pipe(see jpg). That means anytime the switching solenoid is engergized closed, there is air going to the split air pipe.
When is the switching solenoid energized?? I put a wire tap on my ECU's switching solenoid and notice that as soon as you start truckin down the street the switching solenoid is energized closed (1.6v showing on the blue/red wire ). Now if you let off the throttle, the 1.6V goes to 12v i.e. no ground signal from the ECU. When that happens, there is a vacuum on the switching diaphram in the acv, and the airpump air is directed to the Port Air or exaust ports if you will. This happens continuously as you drive and step on and let off the pedal.
For those that did not pay attention, the folk who set their tps using the two bug light method....what you are seeing when one of the two lights come on, is actually the ground signal from the ECU to either the Switching solenoid or the Relief solenoid.

ka8legend

Carl, what kind of an electric air pump were you using to activate your VDI? Couldn't find it on your homepage.

rxhevin

since we have disagreement on the thread...I have removed ACV,EGR, and Air Pump, yet I still have my stock cat. I have the split airpipe connected. What is the effect on my Cat?
-DL