Different Backfire (maybe) issue

[LostViper]

I noticed at WOT I am getting a noise that appears to be a backfire. It usually happens once I shift from 1st to 2nd. As soon as I either let off the gas to shift from 1st or when I get back on it in 2nd. Maybe it's not a backfire, but it definitely sounds like some sort of deep "pop" from the back end when I'm at WOT. Any ideas?

 

[08ms3bm]

Just flat shift the gear

 

[johns]

mods?

 

[Design]

I noticed at WOT I am getting a noise that appears to be a backfire. It usually happens once I shift from 1st to 2nd. As soon as I either let off the gas to shift from 1st or when I get back on it in 2nd. Maybe it's not a backfire, but it definitely sounds like some sort of deep "pop" from the back end when I'm at WOT. Any ideas?

Normal. I get it as well after letting off the gas during WOT. I don't remember the exact science, but it's something to do with unburnt fuel leaving the combustion chamber.

 

[LostViper]

no mods, completely stock (just got it 1600 miles ago)
I don't think it's a clunk in the back, definitely sounds like a deep pop

 

[johns]

word, our cars run pretty rich. it wouldn't surprise me if there happened to be unburnt fuel getting to the exhaust system

 

[tru-boost]

That is the sound of your ehhaust manifold slamming against the firwall during hard driving. Many speed3 engines have literally fallen out because of this issue. Contact protege garage and get a TRZ lower engine mount to fix that problem for good. If you really want to stop the movement get the trans moun too.

 

[Zitrospeed3]

That is the sound of your ehhaust manifold slamming against the firwall during hard driving. Many speed3 engines have literally fallen out because of this issue. Contact protege garage and get a TRZ lower engine mount to fix that problem for good. If you really want to stop the movement get the trans moun too.

Actually - it is back fire, I have all of my motor mounts done now and it happens to me as well, I happen to be a mech. and yes backfiring is the result of unused fuel being ignited in the catalytic converter, hence those cars that dont have cat. conv. show straight fire comming out of the tail pipe. a CAI or FMIC remedies it but not entirely, Methanol will be a big help (big power as well) but whatever lowers combustion temps. plugs that burn larger (e.g. E3 plugs) will burn all the fuel in the chamber.

 

[LostViper]

Thank you for all the replies. It seems that the 2007 MS3s did have a major motor mount issue, but was fixed in the '08s. It definitely seems like a minor backfire. ...now if only I could be behind my car and driving at the same time to make sure haha

 

[tru-boost]

08's didnt fix anything. They still have engines fall out. If it is infact a backfire, i find it odd unless you are running an atmospheric BOV. This isa DI motor. There should be no pooling of fuel like a regular FI car. I would bring it to mazdas attention. Maybe you have a BAD maf.

 

[Bravnik]

Backfiring every now and then is normal. HOWEVER more than just every now and then and odds are its a boost leak. Check all your clamps, make sure they are tight. Also check your Recirc hose.

VTA = Backfiring as well but that is another story.

You should not be backfiring all the time. I get one every now and then with my mods and every now and then is like once or twice a week.

 

[johns]

i backfire. i have a catless dp

 

[tru-boost]

I am pretty much fully modded and never backfire. I did every now and then while i was running vta, but never in recirc mode. I agree though if it isnt happening all the time, its probably nothing.

 

[Zitrospeed3]

Tru boost, you might be on to something, however I think it could be an issue with the restriction in the piping going from the stock TMIC to the throttle body. The "cold pipe" is so restrictive, coupled with an atmospheric BOV and a cold air intake forcing air into the engine, the computer will compensate for the air that isn't going back to the compressor side of the turbo (albeit as little as it is). This is just my brainstorming here, but I do like the troubleshooting. of course there is allways the option of a A/F controller. but that would be in my opinion too much for a car with intake exhaust and bov. Never mind the rambling.(yupnope)

 

[johns]

bov = backfire regardless of your other theories...
it just will.
before catless dp, i never backfired ever

 

[GSXkiller]

If you go an put in those motor mounts your wheels are going to hop like crazy

 

[Zitrospeed3]

bov = backfire regardless of your other theories...
it just will.
before catless dp, i never backfired ever

If this is the case, than why do some of us back fire and others don't?

Ahhh the internal combustion engine, one great enigma... we should just all swap in hybrid motors and sneak up (QUIETLY!) on each other with our healthy green cars. I could see it now in someones sig;

2009 MS3 : Toyota Prius Engine swap, 45 MPG's, and Blue tooth for total control of steering wheel during massive torque steer under full electric mode. (boom03)

 

[johns]

backfires will also occur if you have a leak in the exhaust. a leak in one of the vacuum lines will also cause a backfire.
i've had both of these happen to me

 

[Zitrospeed3]

backfires will also occur if you have a leak in the exhaust. a leak in one of the vacuum lines will also cause a backfire.
i've had both of these happen to me

I have noticed this a lot on MSP's. people do complete hack jobs installing BOV's, boost guages and manifold lines. Vac lines are'nt properly secured etc.. etc..

 

[UHATEIT]

i backfire all the time even when recirculated, i wish there was a way to check leaks from a code reader or something. There are so many noses I dont know where to begin trying to tighten anything. Would it have to be a leak AFTER the turbo, say between the turbo and the throttle body?