necf

I have a 1990 N/A pretty much stock except for the exhaust. I've had it for about a month now. It really likes to back fire whenever I shift above 6500 rpm or so. Should I be concerned about this?

RotaryRocket88

iTrader: (7)

When the cats are removed, backfires and flames on abrupt throttle closure is common.

WannaFD

iTrader: (2)

You should be proud not concerned

funkjaw

iTrader: (3)

Don't do it around a police officer... they will pull you over if they see that. For some odd reason they don't like 5 foot flames shooting out of a car..

13x

look something like this? (just the first video that came up on youtube)

http://www.youtube.com/watch?v=81GPj-oOoY0

canonize-ryda

lol my back fires but not like a machine gun. lol it does one at a time nothing like that..... o man

funkjaw

iTrader: (3)

It's really cool while racing at night like on a canyon or something because everyone else stays off your butt because they don't want their car to catch on fire.

KneeDragger85

mine pops every once and a while while cruising on the highway at about 80mph and just letting off the gas while in 5th gear. never does it when im going through the gears hard tho...

canonize-ryda

mine backfires everytime i change gears or let it rev down while driving from around 5k above.

BomberMan

iTrader: (4)

Backfires are all kinds of awesome, but led me to blow my engine since I was not able to distinguish a lean backfire from a rich one. (apparently the sound is higher pitched when lean, and you don't get flames)

1985gs12a

agreed ^

wjk0817

iTrader: (3)

mine used to pop once in a while, but now it dosent wth

1985gs12a

im not an expert but i would not worry about it unless your timeing is off

1985gs12a

if your timeing is not off i wouldent loose any sleep over it

helghast7

iTrader: (6)

^thats just stupid, of course you should be concerned if your timing is off, especially on a rotary

little backfires are fairly common on n/a rotaries and it only really happens up top

what is your exhaust setup

1985gs12a

i said if your timeing is NOT off (as in if it is correct) if his timeing was off he should get that checked out

helghast7

iTrader: (6)

bahahaha whoops, i should learn to read better at 1 in the morning huh? lol

1985gs12a

LOL its all good haahah

-DC-

my backfire appear when i throttle until the boost kick in and release the throttle straight
it happen because more fuel injected into the engine when boost kick in but unable to burn, am i right ?
so what is the possible reason that cause this problem ?
spark plugs problem ? (fyi the engine is running 4pcs of BUR9EQP when i bought the car and running on 0.5bar boost)
i saw one of the plug slot have some engine oil leaking out
now i just ordered a set of NGK (2pcs BUR7EQP and BUR9EQP) from ebay and awaiting for its arrival, just want to ask...does changing plugs help ?
or what is the sign for such problem ?
Thanks in advance =D

helghast7

iTrader: (6)

preferably you want to run all 9's its a little late for me to remember the technical reasons but everyone i know, including myself has run all 4 9's

its not a problem btw, its nothing you can really fix unless you bring your car 100% back to stock form since mazda developed an anti afterburn system

rotarys are gas pigs by nature, and on top of that theres no place for the unburnt gases to linger like there would be a piston engine, its gas/air in, used/unburnt fuel out even with its ability to cause an internal egr its still pushing out most of the wasted fuel

when the unburnt or wasted fuel hits the cold air out of your exhaust it ignites similar to a backdraft that a firefighter would have to deal with in a burning house

-DC-

thanks helghst7 for the useful info =)
but i do study on the plug discussion thread here, they said running 4pcs 9's if boosting for around 1bar
4pcs 10's if boost 1.5bar or more
for stock boost, normal 2pcs 7's and 2pcs 9's will do
erm....so in my situation, what should i go for ?