There's a backfire sound coming from under the car. Happens intermittently almost like a burp or pop. Had the car in today for state inspection and they replaced the idle control valve but it still has same symptoms. The car is driveable

Faulty ignition components or spark plugs may also cause backfires if the ignition timing drifts off or the plugs fire intermittently. An exhaust leak such as broken welds or other small holes can take in cool air during deceleration and cause a popping or backfiring in the exhaust system.

backfire under load blew your tailpipe/catalytic converter or muffler open...find hole and assess... replacement or repair

need to check your oil level, how old is your timing belt i do wonder if you havent got a broken skirt on one of your pistons

Bad CV joint, very common DEFECT in GM 4wd suv. It will fall apart after awhile at anytime. DO NOT DRIVE till replaced. Had it done on a 1996 Sub. for $250.

sound as bad connection, inspect battery terminals and grounds, also inspect ignition switch connector for bad contact and burned out pins, if so need to replace switch and repair connector, did not stated what year or eng. size

Remove bulb, make sure it sits tight in the socket. make sure socket is not burnt up (brown or black in color) Check bulb, if the filament inside is loose or discolored, replace as nesessary. Check brake light switch under driver side dash above brake pedal. make sure it is adjusted correctly.

At first blush, sounds like the knock sensor making the car misfire. Other possibilities are:

• fouled spark plug; might not notice it at idle but would misfire at higher speeds; check the plugs as well as the valve cover gasket for oil seepage
• if you've noticed a sulphur smelling exhaust or excessive heat from the exhaust, it could be the catalytic converter (more likely if there is high mileage on the car). Another symptom would be very bad performance and poor gas mileage.
  

check distributor cap and rotor button,pops and backfires under a load ,yes sounds like cap and button, hole to help robert b.

It sounds like to me you are having problems with your fuel injectors.  In situations like these there are soooooo many different variables and possible problems, but the fact that the car is backfiring makes me believe that you are getting too much fuel in because that is what makes are car backfire.  When fuel makes it to the cat converter or muffler it will burn there and cause the backfire.  My suggestion would be to start the process of elimination with a good fuel injector cleaner.  The only one that recommend is called Greased Lightening and can be purchased at Napa and O'Reilley auto parts.  If you don't have one of these near you I would go with Techron.  Let me know if I can help you with anything else.  Thanks for letting me help you with your problem and I would appreciate an honest rating on the help that I gave you.  Thanks for using FixYa!

take for diagnostics at a mechanic. please email me at [email protected] with any other info or questions