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help me out- running rich i think.

6K views 12 replies 9 participants last post by  JoeyTakloy 
#1 ·
smog is coming up, and im pretty sure i won't pass.
i think my car is running extra rich, and im wondering if any of this sounds familiar to you guys:

the car is a 1991 miata, 140k mi, and the only mods include an intake; the exhaust is stock and im running a jackson racing cat that is a few years old now.

problem:

the exhaust pops under deceleration, and is full of black soot. someone also told me that it smokes black under deceleration.

also, im losing oil- up to a quart every 800 miles or so but the car isn't leaking from anywhere and all the seals have been replaced. this raises my suspicion that the car may be running too rich and the unburnt gas is possibly washing oil from the cylinder walls during the exhaust stroke (which then causes the pop i hear under deceleration). does that sound right?

this may have been going on for a while, and may have ruined my cat, which is why i am starting to hear the popping and getting black smoke now as opposed to before.

note: the plugs and wires have been replaced not too long ago, and the car feels normal in regards to power.

share your thoughts guys- i have smog coming up in a few weeks D:
 
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#4 ·
check your ignition stuff also cheen

like plug wires and ****

also a megasquirt and wideband would solve this problem

e: when i saw that you were the OP of a thread I had to check that the thread wasn't from 2006 like five times
 
#7 ·
(lol nev)
id really like to get my hands on a compression tester. good compression would alleviate my anxieties. im not getting a check light.

i'll use a volt meter to check the 02 sensor. i'll also check my timing.

does anyone close to SD have a compression tester i can use?
 
#8 ·
okay solved the problem as far as the car running rich- there was a sensor that was unplugged underneath the throttle body. i found it when i was changing the alternator.

no more exhaust pops and no more running bad when cold.

just thought id let everyone know :)
 
#11 · (Edited)
I have the same problem but i figured it was because i do not have a cat I replaced my exhaust with a 2.5 in line with magnaflow exhaust and a resonator I have a arc cold air intake and when I decelerate it launches a nice flame and makes some black smoke too , or when I shift at high rpms it throws a 2feet long fireball can this harm my car in any way ?? I will make a video tonight for you guys to see

I checked for anything unpluged near the intake and its all plugged
 
#12 ·
Sean Jay,

I am experiencing similar issues with my 1.8 and it just started to project black soot (think i just killed the cat recently).

did you ever find out what your compression numbers were? Did you have issues with your rings?
 
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