ok, i have been noticeing lately my car will backfire occasionally upon acceleration. happenned tonight, seemed like it backfired through the intake, not exhaust, immediately upon hard acceleration. only happens then. what does this mean? rich? lean? could this be due to ignition or timing problem??

 

My eng acted like that too. In my case the cam had worn out. The exhaust valves on a couple of cyls were just barely opening.
Might wanna remove the valve covers and start it up. See if the rockers are a rock'in.

A lean condition will cause a backfire thru the intake too.
Could be something as simple as a fuel filter starting to clog.

 

I agree, usually a lean condition will cause it. If your fuel filter isn't plugged, the fuel pump may be bad.

 

very possible that your timing is not advancing right. Might want to check out your timing.

 

mine was doing that and it turned out some of the polly locks were loosening up(the noise diden't chang 'cause the variable duration lifter I use are alaways noisey)

 

A worn distributer can do it. Easy to check, just use a timing light and see if the timing stays fairly constant at steady revs or if it wanders around indicating a loose shaft. You can't always feel the loose shaft.

 

My header bolts came loose, caused me to blow a header gasket. When the gasket blew, it caused my car to backfire.

 

thanks guys, these all seem possible. i changed the fuel filter over xmas holidays. how bout a clogged up Cat converter...would that do it? also, i fear i may have timing issues...not much play in chain though (bout 4*), but timing may be off (no timing light, and never made it to mechanics over holidays). how do you check fuel pump?

thanks guys