I took my car to get it inspected today and it passed. When I was driving home it started backfiring. I checked the spark plug wires and they're all firing (got shocked in the process, wow!). It runs very smooth at idle, but if I rev it at all it backfires. I noticed an exhaust leak within the past 2 weeks that seemed to be getting worse. It sounded like the driver side header collector. But now I can't hear it. I hope it's not like a burned valve or something

Thanks,
Mike89GTA

 

btw, the exhaust smells like gasoline which leads me to believe a cylinder isn't firing. But I checked all the wires using a timing gun and they're all working. Would the timing light blink even if hte spark plug wasn't working but the electricity was just going to the ground or something?

 

If the spark plug gap became bridged by deposits it wouldnt fire.

 

I just unplugged each spark plug wire and it still does it. I noticed a vacuum hose is broken. Would this cause backfiring? It's the vacuum hose right by the distributor, here's a pic.

http://66.61.58.118/stuff/hose.jpg

Here's a video of the backfire..
http://66.61.58.118/stuff/backfire.avi

dimented24x7: The spark plugs are relatively new so it's probably not that.

 

Is it backfiring thru the exhaust or in the intake? Exhaust could be due to the leak. Intake would be if you're running lean or if the timing is some how off. If you have a vacuum leak, I would think the car would idle a little rough.