ok here is the deal i was driving my FC and it was fine! no problems had the car for about a month! i want to get some gas on friday and i drove it maybe 45 miles. On the way home from my little trip it started backfiring at first it wasn't bad. one here and there then by the time i got 10 miles from my house it was backfiring really bad and i wasn't able to make it home at one point. i pulled over let it idle for a few mins then i stepped on the gas pretty hard and not backfire. so i said here is my chance. i took off and it was backfiring and hesitating really bad. then it stopped i had full power back and i was able to make it to my block as soon as i slowed down it started backfiring again and i had no power. i took the spark plugs out last night and they where black! but here is what i don't understand i waited for the next day and i drove it around my hood for a few and it was fine. as soon as the car got to norm temp it stared backfiring again. like it had no spark. or no fuel going, but it idles with no problem. so i got home and i waited for the engine to get cold. like 5 hours and i went out again and i had my wife step on the gas and the smell was so nasty from that exhaust! it smelled like eggs where in my exhaust. now could this be a case of bad gas? fouled plugs? i need help!???

 

what gas did you put in? maybe dumb to ask but sure it wasn't diesal.

 

lol nah not that man i put in 93 from amacco i don't think they even have diesal there

 

If its a n/a, use regular next tank.

 

nope it is a t2

 

i'm not a turbo kinda guy but you say that it smells like rotten eggs ..that IMO sounds to me like a coolant seal..coolant will smell like that ..could be the reason for backfiring ..suckin coolant into the engine and it temporarily fouls the plugs ..then Bang!..dry plug .ignition normal ..spark..backfire...........you'll receive more input on this from others but this is my take on it..post your status ..curious.

 

if it was a coolant seal wouldn't the temp shoot up? also the engine has 10k on it built by mazda

 

it idles fine? maybe a clogged fuel filter. . ? Also, rotory exhaust smeeellllls terrible. . no way of geting around that until you get a good tune on it.

 

also if i leave the car running at idle it runs fine and the temp never goods up it stays normal, even when it is warm and the temp never goes up.

 

Not necessarily. If it was big enough to cause the problem he suggested... probably. Just check for bubbles in the coolant while running, or pressure test it to be sure.

 

does it start to happen at any specific rpm/ boost. Is the stock boost gauge still working? Maybe a boost sensor problem. My money still might be on the fuel filter though

 

i don't know how to do a pressure test, but wouldn't is smoke? white smoke? and also would i lose coolant? my coolant is still nice and full

 

but dam why would it run right when it is cold? it does start and start good and idle great but when it warms up and when i am out the drive way it is killing me

 

what color black are the plugs... like an ashy or glazed black? I think the egg smell was just cause you had a cold catalytic converter. may have a vacuum leak at the lim/uim thats only opening up when it gets warm... expansion kinda thing... just throwing some ideas around.

 

i would guess ashy it is not wet and it isn't shiny when i think glazed i think shiny so i would say it looks more like a flat black

 

compression test will tell you..said it smells like eggs..coolant,,runs good until warm ..when the thermostat opens up and the cooling system comes under pressure ..TA-DAH..right?..also the temp won't shoot up if it is SUCKING coolant..intake cycle..if it was overheating you would be lookin at a seal at the compession or power cycle..heat or air from inside goes into the cooling system and shoots up the temperature..jesus bad,sweet smell,backfire all the symptoms are there..someone back this one up!

 

can't back you up, don't know what you're talking about!

 

I had this problem last year and I ended up replacing the cat... It had collapsed so much that it was not allowed the engine to totally breath- You said that you smelled rotten eggs...what you could be smelling is emission's + the normal smell of a rotoweee! Anyway... That is my experience/opinion and we all know about those...

 

well i pulled out all the spark plugs today and they where BLACK the prong in the middle was covered in carbon i don't know how there was spark coming those plugs i am going to clean them up good tonight and put them back tomorrow and see what happens! everyone locally that has heard the car or seen the car are all saying it is a spark issue, because if i press in the clutch and give it gas it wants to rev up but it has something stopping it so i am going to start with the plugs and the cables. two guys also said it seems like i got water in my gas because it didn't start until i got the gas on friday so i will see about that also. and what do you think being that the car is down right now is this a good time to install my walbro 255?

 

Sounds like there is a problem with the cat. Burning coolant does NOT smell like rotten eggs! Coolant burning is a sweet smell. Rotten eggs = CAT

 

what about the tps? could that be a factor?

 

The backfire was like this one????

 

lol hell no i dont think i have enough power to even get that kind of backfire

 

i fixed it! it ended up being my boost sensor!