Now how do you stop the backfiring through the exhaust. (without reinstalling the AIR pump) thier must be a way, has anyone found it.

 

headers.

anything else is bubba

 

If you are having back-firing through the exhaust, then I would not think that is from removing the air pump. I removed my air pump on a 81 and had no problems at all. I would think the back firing is being caused from something else. Maybe someone else can chime in and help.

Good Luck Tim

 

what do you do to cause the backfire?

 

Not exactly sure because my car didn't come with an A.I.R. system....
From what I remember by looking at cars that have air pumps, there is some sort of tube that plumbs into the down pipe just below the exhaust valve located on the bottom of your right side exhaust manifold. If you removed the A.I.R. pump without capping that tube, then you could get something that sounds like a back fire from time to time, especially when you close the throttle. There also is some other component that closes the exhaust valve under certain conditions. It is called an Early Fuel Evaporation valve and I suppose it has something to do with excess fuel that may be unburnt during cold starts. This could also be causing your backfire if fuel is allowed to gather in the system. I think the air pump injects air at the point where excess fuel would collect and helps burn that off before it gets to the catalyst.

If you took the time to remove your air pump, you probably should also wire your exhaust valve open so it doesn't close when it gets the vacuum signal. I suppose if you are going that far, you may also consider installing block off plates in your intake manifold gaskets to render your EGR system useless. It does help with power, but takes a bit longer to warm up the engine on cold days.

Just some ideas. I hope you find the source of your problem soon.

 

Is your car backfiring, or just popping when the rpm's are dropping? Also, what kind of exhaust are you running? I had a dual chambered exhaust with no cat and no mufflers, just long chambered sections, and when I removed my AIR system, it would pop like crazy when the rpm's would drop.

I must agree that the only way to fix the problem would be to install headers, or, depending on your year, you can buy threaded plugs that screw right into the holes in the manifold. You could also look into some quieter mufflers, but who wants that

Headers are best, though.

 

I removed the A.I.R. from my 73 sb and there were no issues with the exhaust at all.

 

I removed the AIR pump on my 75 with no issues. Just changed out the exhaust parts with one pre AIR pump. At minimum cap hole in exhaust.

 

The AIR pump merely forces [clean] air into the exhaust in hopes that any excess hydrocarbons will be burned off [and so that any remaining hydrocarbons will be diluted in the exhaust gasses so their concentration will not exceed government standards]. Removing it will not cause "backfiring". You did plug off the AIR tube entry holes in the exhaust manifolds, didn't you?

 

I stole this picture from the CAC



I think this is your exhaust manifold (but I dont know what year you are referring to and if you ask my wife, I suck at reading minds)

nonetheless, if you removed your pump and you now have an open hole from your exhaust, you are hearing noise from the open hole because nothing is stopping it emminating from the hole(s)

I imagine you could go to Lowes or Home Depot and get a pipe thread cap for the big hole making noises (that'll be pretty in your engine compartment, bubba), or get really bubba and take a hacksaw to the 4 feeder tubes and crimp them with vice grips (ask me where I got this idea)

or


go buy some headers

 

You can do one of the following: Take your car to a shop that specializes in custom exhaust and have them remove the A.I.R. tubes from your exhaust headers - they will cut them off and either weld the holes close or install screw caps. That don't look out of place. This all depends on your Exhaust headers of course - they are either the heavy cast iron ones or made out of steel like on my 81 - it came with stainless steel shorty headers.

This is what I did: 1. Removed all A.I.R. components from the car
2. Removed and saved all components of the original exhaust system to include - shorty headers (with A.I.R. tubes installed). Mufflers and CAT converter and A.I.R. pump and all nuts and bolts etc. In other words anything than needed to be saved to return the vehicle to factory exhaust standards.
3. Installed HOOKER Stainless steel side exhaust headers, pipes and STEEL Shield side pipe heat shield. (looks great, made by a forum member at the right price and installs with a factory look)!

I haven't had time to clean the car up and take pictures, but I will soon.

 

Tyler, under what driving conditions is the backfire occuring. I am assuming it is under de-acceleration. Is it one big backfire after coming down from high RPMs or is it a series of small backfires as the engine de-acclerates?

 

I have a 1980, my exhaust manifold does have the threaded AIR pump tube holes and I do have them plugged. the popping comes from deceleration in a series of small of backfires.

 

Try advancing your timing 2 degrees.

I did the air pump removal and pipe capping the AIR ports, and noticed some backfiring when I let up on the throttle that was never there before. After a 2 degree base advance (CFI is ECM controlled), the backfiring is gone.

Brent.

 

If advancing the timing still does not cure it make sure you that the plugs you put in are sealed up well and also that your exhaust manifold gaskets are not leaking.

 

That is not backfiring...a backfire sounds like someone is shooting a .50 cal through your carb. Your car is running a little rich, or as MN-Brent said you need to adjust the timing.

 

OK thanks, I will advance timing 2 degrees and see if that does the trick. I used a stethoscope to listen to the exhaust plugs, no leaks.

tyler77