air filter box

[bubba12]

i have a 2002 cng cavalier and it has seemed to backfire a couple times on cng and it has blown off the top of my air filter box

[CNG Utah]

Re: air filter box

The most common cause for this is pressing the gas pedal while starting the car. Because of the design of the CNG system in a 98-02 CNG Cavalier, you should never press on the accelerator while starting the car.

[bubba12]

Re: air filter box

ok thank i also noticed in some of the later post some one suggested changing the spark plugs so maybe ill try that to

[siai47]

Re: air filter box

Also look at (and replace) the plug wires. The air filter cover is the same for the CNG as the standard car--go to a junk yard and pick up a couple spares. Drive long enough and you will use them up. When you change the cover, make sure the bolt holes in the air cleaner body aren't broken. Anytime it backfires, remove the cover and be sure the air filter element hasn't been damaged.

[larrycng]

Re: air filter box

I would replace the filter element. You can't really tell if there are some small ruptures in the filter media that will allow fine dirt and other abrasives into the engine. I was told a long time ago in a John Deere class that John Deere will void and engine's warrante if they find out that you have "blown out" the air filter element with an air hose. I have also been told not to blow out filter elements from an old mechanic when I was just young in this business (they had phased out oil bath air cleaners on passenger car by this time).

The filters don't cost that much compared to engine parts

Larrycng

[csmeutah]

Re: air filter box

Wouldn't an aftermarket k&n canister filter fix this? I'm thinking the gas seeps up and gets trapped. A canister filter would let it escape?

My car doesn't like to start without a little extra gas.

[siai47]

Re: air filter box

Don't remove the original filter box or replace it with a K&N. The factory filter vents and receives air from outside the vehicle. You don't want residual NG venting under the hood. If member csmeutah needs to push down the accelerator to start the car, something is wrong. Usually there is a small leak somewhere in the intake system or the low pressure regulator is out of adjustment. Pushing on the accelerator during starting is the best way to blow up the air box. From past experience I am a guru of air box destruction.

[ericguy320]

Re: air filter box

Gm cover replacement of the air box with a redesigned lid that has pressure release baffles in it, if your car is under 10years or 100k miles it is free
look up #04008: Special Policy Adjustment - Air Cleaner Cover-Replace the part # is 52372980

[siai47]

Re: air filter box

I had a Cavalier with the modified airbox installed. That really worked well because the bolts that held the relief valves to the cover held all the broken pieces together when a backfire blew it apart. Somewhere I posted pictures of that thing on this site. The key is to try to stop the backfire in the first place. Lean conditions when cranking help cause it. Trying to start holding the accelerator down leans out the mixture. A false start will also trigger the problem. This occurs when the car tries to fire but then stalls. The residual gas in the airbox explodes when you try to restart. Bad plug wires and/or spark plugs can also cause a misfire when first starting causing the problem. If your plugs and wires are in good condition it could also come from leaks in the intake system or low pressure regulator problems. When starting the car be sure to keep cranking the engine until you are sure it is running. If it stalls, wait a couple of minutes before you try a restart.

[csmeutah]

Re: air filter box

Yeah, I replaced the airbox. Car takes about 5 seconds to start; I'm just impatient.