HEY GRUMPY?<I have a situation I can't seem to figure out. My engine is backfiring through the exhaust on deceleration. The harder I let the car brake with the engine rpm's, the louder the backfire. Unfortunately it also does it between shifts.
If I get back on the gas just slightly between shifts, I can avoid it. So to me it seems like it's happening under high vacuum.
I am starting to scare the heck out of other drivers as I come up to a stop light and I arrive with a BANG!. I can't seem to find any vacuum leaks and I don't hear any exhaust leaks either. Anyone have any advise where I should start? Do these plugs look like they are burning too lean? They do seem more white than tan. Here are what my plugs #1 and #3 look like:
This is a new one so there is something to compare the others to regardless of color differences in monitors.
yeah, sounds like a vacuum or exhaust system leak,back fires are unburnt fuel air trapped in the exhaust thats ignited by a different cylinder exhaust flame,or exhaust heat,if you get the car up on a lift and dribble just a tiny trickle of water mixed with oil into the carb the resulting smoke would show the exhaust leak location, id also look for a bad carb to intake gasket loose mount bolts or missing or leaking vacuum hoses, a leaking brake booster could in rare cases be the cause
btw the plugs indicate your engines running a little bit too rich at idle , your running a bit to much ignition advance and your running a bit to lean in the upper rpm ranges, Id back off the timing 1-2 degrees and go to a power valve with a next higher number or richer secondary jets and check float levels, and fuel pressure
If I get back on the gas just slightly between shifts, I can avoid it. So to me it seems like it's happening under high vacuum.
I am starting to scare the heck out of other drivers as I come up to a stop light and I arrive with a BANG!. I can't seem to find any vacuum leaks and I don't hear any exhaust leaks either. Anyone have any advise where I should start? Do these plugs look like they are burning too lean? They do seem more white than tan. Here are what my plugs #1 and #3 look like:
This is a new one so there is something to compare the others to regardless of color differences in monitors.
yeah, sounds like a vacuum or exhaust system leak,back fires are unburnt fuel air trapped in the exhaust thats ignited by a different cylinder exhaust flame,or exhaust heat,if you get the car up on a lift and dribble just a tiny trickle of water mixed with oil into the carb the resulting smoke would show the exhaust leak location, id also look for a bad carb to intake gasket loose mount bolts or missing or leaking vacuum hoses, a leaking brake booster could in rare cases be the cause
btw the plugs indicate your engines running a little bit too rich at idle , your running a bit to much ignition advance and your running a bit to lean in the upper rpm ranges, Id back off the timing 1-2 degrees and go to a power valve with a next higher number or richer secondary jets and check float levels, and fuel pressure