Exhaust backfires, running rich, poor mileage....come in! (AIR removal)
 

Guys,

I've wanted to remove the AIR system in my car for quite a while, so I decided to tackle the job this weekend. I had read this article in preparation for the job. It explains how to remove all the major components, but doesn't go into details about what to do with vaccum lines and other small parts. I took pictures of the process, so whenever you try this, you won't be as lost as I was. Without further delay, here they are:

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I should add that I was having some serious backfires through the exhaust. I suspected the AIR system may have something to do with it, but couldn't confirm. Upon removal, I found out one of the check valves was not sealing at all. They are supposed to be a one-way valve, but the passenger's side was not sealing either way. This in turn allowed fresh air to enter the manifold causing shotgun-like backfires. This problem was also tricking the O2 sensor on that bank into believing the engine was running lean, therefore advising the PCM to dump more fuel, which showed up in my last oil analysis.....it was 1.8%.....normal is 0.5% or less. My gas mileage has also been somewhat crappy lately, so this fix should definitely restore mileage back to normal.
If you are having backfires and seem to be running very rich for no apparent reason, check your check valves....they could be bad.

Hope this is of help to someone.

Rick

where are the check valves and what exactly do they do?

Look at picture #4. See where the nuts are on the pipe? The black saucer shaped thing? Inside there! The valves are basically one-way flaps, which allow air to go from the pump into the manifolds, but not back to the pump. I had one that wasn't sealing at all. That leak was wrecking havoc with my air/fuel ratio and causing real bad backfires.

I don't understand your problem, your car is running now right?

Yes, the car is now running right!

The problem WAS horrible backfires through the exhaust along with an extremely rich condition. The car was running so rich that I had almost 2% fuel in my oil last time I did a Used Oil Analysis! What caused that was an open pathway (or basically a massive leak) in the exhaust system. Exhaust gases and fresh air was moving back and forth between the intake lid and the exhaust manifolds. In fact, I disconnected the hose from the lid and there was suction or vaccum, but the AIR pump was off. You simply cannot have unchecked air moving at will between intake and exhaust.
Simply put,the check valves will eventually burn up or wear out and give you lots of headaches. People who install headers get this problem almost right away; but as I found out, it isn't limited to headers only......they'll wear out on a 100% stock car as well.

Rick

Great post. I think my AIR pump motor might be crapping out. I may just remove the whole thing.

That's odd......I removed my A.I.R. system on my '99 and it didn't look anything like that. My air pump was bigger and rounder, and I didn't have all that stuff behind the intake manifold. The two hoses that ran down to the manifolds were connected into one hose that ran along the driver side fender well and down to the pump. I pulled it all out and there was nothing to cap off. My car picked up 3 MPG with the header install and it runs great, so I doubt I have any vacuum leaks. Is this normal for a '99 car?

Hmmmm, maybe they changed the system to what I had. Anyone has any info on this? A change could also explain why the article I linked in my first post is so incomplete......at least to those who have the same system I had.
Most likely a change!!

Yes the AIR system was changed in 00' But your writeup is still pretty good. Anyone with a 98-99 should still be able to follow your directions. The only differences are as listed above.

Pardon my ignorance, but what exactly does the AIR system do? Is it beneficial to remove it, performance wise?

Thanks

it is designed to provide fesh air for the catalytic converter to use to catalyze the hydrocarbons that didn't get burned in the chamber. if you don't have cats any more, its just extra weight.

that's a outstanding write up!

this is great, you don't know how much I appreciate this. I have been dealing with this backfire problem for over 2 years, I just had a dyno tune using ls1 edit and stii could not figure out the problem. After reading this I took out the air pump and all backfires gone plus the car runs better. Thanks a bunch.
:cheers:

Very well done! I evidently missed this when it was posted. I was going to do this about 100K miles back, LOL.

great write up!!! now if I may...how the hell did you get that 15mm bolt off the back of the driver's side cyl head??!!! I can get a wrench on it, but cant turn it, any tips/tricks would be greatly appreciated. So far all I have done is remove the check valves and made my own block off plates. Thanks!

Very good write up Rick. I have a 2000 and also removed the AIR a few years ago using the link you posted. Supposedly this model year had the extra crap that the other models didn't have and can be confusing. Thanks for clearing it up! Anybody know the official name for this part that mounts by the coils? I never removed it. Just plugged the line. :)

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I wonder how long it takes for the check valves to die. I've had my car almost 4 years, 43,000 miles and most with headers and AIR restrictor plates(make the hole smaller, dont totally block off) and havn't had any problems yet.

Good job!

Great pic's!

That was a great post man, I was going to do that this week, now it makes life 100x easier.

good stuff, added to the exhaust guide