back fire ???????????

[PKRWUD]

Posted by Unit 5302:
Your exhaust is not directly related, but if it causes the engine to run lean, could be an indirect cause

The one exception is when you have a hole in your exhaust. For example, if you are missing a collector bolt, or if the collector is bent, you will cause a backfire when suddenly backing off the throttle. This is caused by the vacuum that is created in the pipes when you back off, pulling air in from outside. The oxygen rich outside air explodes when it hits the high internal heat in the pipes. I had this problem with my Chevelle in the mid 80's, and it drove me crazy. There was a collector bolt that had backed off, and I couldn't see it because of it's location. Once I finally found it, and fixed it, the backfire went away.

Take care,
-Chris