Excessive Backfires...help!!!

SERI3S · 10-22-2007, 11:44 PM

hey guys my 83 SA22C 12a is backfiring terribly at every gear change when the revs are above 3500 rpm i have 3 theries as to why it may be happening they are *i bought it from an old lady and she probably never drove it hard,
so it could be a bit coked up
*i just put on an after market 4.4inch 3A racing cannon muffler
*or it needs a tune as it is running a bit rich i think

if anybody can tell me the reason it is doing this i would like to hear it very much, i will post a video of me driving it with the camera on the tacho later so you can understand how bad and frequent they are
thanks guys i need your knowlege, will.

Supersonic · 10-23-2007, 12:50 AM

By the time I read your first line I was thinking it was running to rich.

A backfire is unburnt fuel igniting in the exhaust system, so that means that you're not getting full combustion in the cylinder. You should pull your plugs and check to see if they are fouled, or have large black deposits on them.

It could be carbon build up and a good flogging might cure it, but I think it's a little more then that.

Also, with that exhaust system you might not be getting enough back pressure.

Ok, I didn't help you since I confirmed most of your ideas

Running rich, that's my bet. Post the vid though, I'd like to hear it for myself.

The good thing is it ain't a major thing to fix.

rick2 · 10-23-2007, 03:00 AM

sounds like what we ran into when we removed the catalytic converters from our '87, and didn't disable the smog pump.

Your new custom exhaust happen to delete any cats?

Signal 2 · 10-23-2007, 06:47 PM

+1 for changing plugs and run a good fuel system cleaner, carb adjustment and timing check. If it persists and you still suspect carbon as an issue, consider distilled water treatment, but that can be a little risky.

SERI3S · 10-24-2007, 12:14 AM

Thanks heaps for the feedback guys i will check the plugs and possibly get a rotary specialist to tune it for me, and the exhaust i put on is just a muffler at the very end of the exhaust it still has the exhisting stock exhaust system running all the way through thanks guys you will hear from me soon, will.

Mindcore · 10-24-2007, 11:15 PM

Then it's not likely your muffler. As these guys said, I'd look to the plugs first.

How is it for power? feel a little sluggish?

Jimbo · 10-25-2007, 11:30 AM

I agree with signal on all counts, but..that water treatment can go bad, I'd avoid that.

10-22-2007, 11:44 PM	#1 (permalink)
SERI3S Junior Member Join Date: Jul 2007 Posts: 12	Excessive Backfires...help!!! hey guys my 83 SA22C 12a is backfiring terribly at every gear change when the revs are above 3500 rpm i have 3 theries as to why it may be happening they are i bought it from an old lady and she probably never drove it hard, so it could be a bit coked up i just put on an after market 4.4inch 3A racing cannon muffler *or it needs a tune as it is running a bit rich i think if anybody can tell me the reason it is doing this i would like to hear it very much, i will post a video of me driving it with the camera on the tacho later so you can understand how bad and frequent they are thanks guys i need your knowlege, will.

10-23-2007, 03:00 AM	#3 (permalink)
rick2 Senior Member Join Date: Jun 2007 Location: Henderson, NV Posts: 243	sounds like what we ran into when we removed the catalytic converters from our '87, and didn't disable the smog pump. Your new custom exhaust happen to delete any cats? __________________ '87 Blue RX-7 Coupe - the race car '99 Green MX-5 Roadster - my daily '77 RX-3 SP - the project car

10-23-2007, 06:47 PM	#4 (permalink)
Signal 2 Member Join Date: Aug 2007 Location: Midwest Posts: 34	+1 for changing plugs and run a good fuel system cleaner, carb adjustment and timing check. If it persists and you still suspect carbon as an issue, consider distilled water treatment, but that can be a little risky. __________________ Mostly stock, 93 VR R1

10-24-2007, 11:15 PM	#6 (permalink)
Mindcore Administrator Join Date: May 2007 Location: Look Out!!! Posts: 1,299	Then it's not likely your muffler. As these guys said, I'd look to the plugs first. How is it for power? feel a little sluggish? __________________ core Mazda Forums .

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10-23-2007, 12:50 AM	#2 (permalink)
Supersonic Senior Member Join Date: May 2007 Location: New York, NY Posts: 345	By the time I read your first line I was thinking it was running to rich. A backfire is unburnt fuel igniting in the exhaust system, so that means that you're not getting full combustion in the cylinder. You should pull your plugs and check to see if they are fouled, or have large black deposits on them. It could be carbon build up and a good flogging might cure it, but I think it's a little more then that. Also, with that exhaust system you might not be getting enough back pressure. Ok, I didn't help you since I confirmed most of your ideas Running rich, that's my bet. Post the vid though, I'd like to hear it for myself. The good thing is it ain't a major thing to fix.

10-24-2007, 12:14 AM	#5 (permalink)
SERI3S Junior Member Join Date: Jul 2007 Posts: 12	Thanks heaps for the feedback guys i will check the plugs and possibly get a rotary specialist to tune it for me, and the exhaust i put on is just a muffler at the very end of the exhaust it still has the exhisting stock exhaust system running all the way through thanks guys you will hear from me soon, will.

10-25-2007, 11:30 AM	#7 (permalink)
Jimbo Senior Member Join Date: May 2007 Location: Toronto Posts: 161	I agree with signal on all counts, but..that water treatment can go bad, I'd avoid that.

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