What's backfiring when shifting a sign of?
 

Just as the subject says, what's backfiring when shifting a sign of? It only happens when I "give it the juice," not when I'm casually driving. Just a "pop" from the exhaust when I shift from 1st-2nd, 2nd-3rd, and sometimes 3rd-4th. It also bogs more than it should when I attempt to go forward by simply letting the clutch out without hitting the gas (Terrible for when I need to stop, then go on a hill, and NO, it's not the driver! ;) ) The carbs been tweaked (Factory Nikki), foam air filter (Need to find a K&N) 2 cat's replaced with presilencer. Are these signs of a bad fuel/air ratio? (High/Low) Thanks-

It looks like the car is rich. When you are getting on it, it seems to be getting a bit more gas than it can burn. Between shifts the car is fed too much fuel and it isn't burned because there isn't enough air to go with it(because the throttle plates are closed momentarily). So the unburned gas is ignited when it enters the hot exhaust making backfires. All that emissions stuff helps reduce this factor, like the decelerator that leans the engine out when the throttle plates are slammed closed after a wide open situation. Also a more free flowing exhaust with good scavaging of the exhaust will cause some of this. The only thing I would do is gat a good AF meter andf tune it on the top end a bit. If it is too rich then leaning it out will get some more power.

Check your afterburnhose at the rear of the carb heres a pic at Mazdatrix http://www.mazdatrix.com/c-5.htm
it can cause all kinds of problems and they have a tendency to burn thru be cause of the heat.

It's a sign that it has a rotary under the hood :D

amen.. backfiring is nothing to be afraid of.. it is one of our trademarks

backfire is either really rich AND/OR exhuast with some leaks. Usually between gaskets is VERY common. Also check the wields around the flanges between exhuast components for pin-holes. Re-wield them and you'll eliminate it...along with new gaskets if you see a lot of carbon going all the way to the side of the gasket...

Hell yeah! :D That's exactly what I was thinking when I saw the subject of this thread. ;)

Much appreciated guys, I'll see what I can do! (It's probably a combination of some of those factors :p: )


This forum's great!!