rybrx7

was having a bit of a race last night with an AMG, and before you say it yeah with a near enough standard FD i dont stand much of a chance except for top speed but i couldnt resist

now to the problem

i get lots of backfire out of my exhaust (apexi) and it seems to make the car shake, is that normal?? the thing is it seems to stop the power delivery so the car seems to stutter, is this because the air is being eating up by the flames??????

its gettin pretty annoying now as i cant accelerate too hard with it happening,

spark plugs solve this???
decent air intake rather than stock?

93BlackFD

revlimiter

rybrx7

eh??? i never got near the rev limiter!

Snook

iTrader: (12)

is the map sensor still on both places?

I have no idea what you are talking about so I'm just guessing.

PM me with more details if you'de like

how long has it been since you last changed the plugs? are the plug wires stock?

Street King

Change your plugs if this is happening anywhere below 8k rpms.

rybrx7

how often should you change your plugs i havent changed them since i got it 3 months ago

and snook, im not technical with cars in the slightest so i have no idea what your talking about lol

meddle

My plugs last about 10k give or take.

rybrx7

is that driven hard or not?? i think mine will prob be about 5k old, maybe 1k give or take,
dont drive my car daily but when i do i drive it hard!

TTurboXfd3s

well rotary tends to backfire at low rpm's too! it used to always happen to mine when i'd downshift everytime almost! but after a while it stopped happening, wether it was because i did something it it just happened to stop! =/

rybrx7

it only usually happens from about 3000 revs onwards, im not on about the machine gun popping noise that just sounds cool, these are really loud pops from the rear of the car and it spits flames apparently too when it does this. im ok with that bit, but what i dont get is why this would stutter the power on off on off on off, would sparks plugs cause that???

suprfast

fuel cut. im almost sure. go ahead and list your mods. we will get to the bottom of this. if you are shooting flames then you have a wide open exhaust. if you dont have an ECU then you will be getting a new motor. if you have an ECU then it could be fuel cut. mine did that too before i put in a restrictor plate and played with the settings on the PFC a tad. im still running too rich, but enough about me. what are your mods
kris

rybrx7

its completely standard apart from an apex'i exhaust!
only had it 3 months and had a new engine around 5000 miles ago!

suprfast

well here is my take on this. you dont have a cat, or one of the high flows. you are shooting flames which is usually assossiated with open exhaust. your stock ECU is not able to handle the spikes(jerkiness) that you are getting when accelerating. you keep hitting fuel cut. you need to address this fast, as a new motor will be in the future. i am sure you are spiking and hitting fuel cut. it might be ECU time or atleast a boost conrtoller to hold you at 10lbs. do it right, keep the name of the rx7 good to those who do treat it good
kris

rybrx7

hmmm thought as much.

i only have a basic understanding of this but if im running rich and shooting flames, lots of unburnt fuel, wouldnt improved air flow, i.e. a better air intake like the apexi help this??

or am i just off in my own little world talking rubbish?

suprfast

well taking fuel out would be the best way. you shouldnt be running rich with just the exhaust though. double check all your parts to be sure you are stock. i also have an apexi intake for sale if you are interested. check your plugs and read them to us, or just post a pic of them.
white=lean(bad)
brownish=good(just right)
black=rich(better than lean)
kris

rybrx7

hmmmm well i'll have a look 2morrow but im pretty positive im stock other than that. due for a service soon so i will see if that sorts it then if not i'll splash out on a ecu

is the power fc good enough do you reckon? motec sounds very good but pricey!

suprfast

i have the power FC and i love it. just getting familiar with all the other goodies on it, but for the stuff i plan on doing it works great. im sure the AEM would be nice, or the haltech, but seems like more of a headache. get the PFC and you can do many wonderful things with it.
kris

Street King

Just because you have an open exhuast doesn't mean you are going to pop your motor. i have had mine opened up without ecu for over a year with no problems. You just have to keep your psi at 10 like mine with out creep.

skunks

yep yep i agree, I'm running dp, mp, catback all about 3-3.75 inchs straight back/straight thru type and I only have the stock ecu. I keep my boost under control and at 10psi to redline and I have been fine (I alwaysn get on it too, gotta keep those tires spinning )

BTW: Back firing is just you running a bit too rich which is totally normal with a FD (especially with a stock ecu when your with in stock boost levels). Perhaps you should get a PowerFC and get on a dyno and get your car tuned properly. (you should still be backfiring btw )

rybrx7

well i'll start saving for one then!!

and if my plugs are old would this cause me to run rich???

skunks

It might, our plugs last about 10k miles or so but if your running super rich, it can get fouled faster.

DeepInTheGame

I have the exact same problem... It doesn't happen in first though, only 2nd and third, it get's bad in 2nd, but not too bad in 3rd. It doesn't do it all the time, but rather maybe once every 3-5 days I run higher boost, but on the days that it does happen it happens like 1-5 times. I have m/p, hks intake, avc-r and BOV, it doesn't happen on stock boost levels, only when I put it to 12PSI, which I hardly ever do. any help?
And BTW, a stock FD can handle most AMG benz's. It should handle all except the e65, and maybe the SL55, but they don't have manual, so a good driver could probably take them. I don't think an SL55 runs 13.5 1/4, which I have seen in a stock fd

Matt Hey

You might also check and/or add grounds. The ECU will default to pig rich condition (causing backfiring) if certain sensors don't make sense (even for a short amount of time). I added a ground by the power stearing pump (like Pettit) and one at the bottom of the downpipe for the O2 sensor. It solved my backfiring/smoke ***** mostly in the mid RPM range. Clean stock grounds as well. Your plugs should be cleaned or replaced as they are likely fouled now. Good luck.