Gunshot Pop From Exhaust&Black Smoke/Soot on rear bumper

[ayororo]

Hey guys, I gotta s13RedTop in an s14..

It seems its running rich kinda smells like a go-kart,

theres some blacksoot on bumper near muffler, and muffler turning blackish..

When I start pulling&Boosting Blacksmoke comes out of mufler I can kind of see it behind me..

and when im decelerating in gear while the rpms drop it makes the infamous GUNSHOT POP and I see some blacksmoke behind me.

Ive searched google etc but all of them had more symptoms I dont have,

The car honestly runs great&pulls hard So I dont thing theres piston/ring damage or im riding on 1 Less cylinder, boosts to 0.4 Bar, I have stock Side mount

I have stock SR with only CatBack Blitz Exhaust So I still have a CAT.

[chituntang]

running rich, un-burn fuel passing through cat, and heat in cat ignite fuel, and make noise...

[ayororo]

Lol I know that but I just wanna know what I should check, cuz everything runs fine..pulls hard,

So what could it be?

Fuel pressure regulator?
Maf
Turbo Leak?
Bad Timing?


the gunshot only happens when I decelerate off throttle in gear,

I just wanna know what exactly fits my symptoms,

Specifically The Black Soot&BlackSmoke Under accel, and GUNSHOT Pop..

The car runs hotter than normal if the heater isnt on as well, but I still have stock KA radiator, Stock side mount, Stock manifold stock downpipe & cat

[S14DB]

My first thought is the the timing is off.

[ayororo]

Alright try to do the timing, can i just adjust that bolt at the distributor

[StReeTz]

Is the car tuned? Are you recirculating your blow off valve or does it dump straight to atmosphere?

[ayororo]

I stated car is all stock, im pretty sure it has stock bov, so I think thats vented into atmosphere rght?

[s14freak93901]

its called a cas not a distributor.

[ayororo]

Okay^ thanks..

[idahotuner]

leaking o rings on your injectors

[Dolph_KYAS13]

bad vac leak?

[KaminaSan]

Mine does this every single time I boost, and the BoV goes off, when it decels to 1500rpm.

Never did that when I had the SMIC/stock bov.

Are you 100% stock?

[nismoman]

Check the coolant temp sensor.

[StReeTz]

Mine does this every single time I boost, and the BoV goes off, when it decels to 1500rpm.

Never did that when I had the SMIC/stock bov.

Are you 100% stock?

If your blow off valve vents to atmosphere and is close to your mass airflow sensor then the discharged air will be read by the mass airflow sensor causing a rich spot upon sudden throttle closing or blow off. You can recirculate the blow off valve or make sure the MAF isn't too close to the blow-off valve.

[KaminaSan]

If your blow off valve vents to atmosphere and is close to your mass airflow sensor then the discharged air will be read by the mass airflow sensor causing a rich spot upon sudden throttle closing or blow off. You can recirculate the blow off valve or make sure the MAF isn't too close to the blow-off valve.

The MAF is on the intake, and I already knew about recirc etc. I appreciate your information, but I was actually trying to hint to the OP that if he has his BoV vented, it will cause this backfire upon decel.

[ayororo]

I am 100% stock cept for catback.. I post it in original starter but ppl keep asking lol, but yeah, just a blitz catback, so leaky O ring from injector? Causes black soot on bumper and smoke when boosting? And the gunshot doesnt happen when boostin can just cruise and do it

[nissanguy11]

my RB20 does this shit all the time.

its not stock tho, im boosting 1 bar on a RB25 turbine.

[doomviillain]

It could be a number of things, maybe your timing. If I had to pick one according to your symptoms I'd say its ur BOV. When you let off the gas there is a split second where the AIR/FUEl gets super rich because he has an atmosphere dump on the BOV. You will see less smoke when resirculated but it will still smoke because it is getting less air from the turbo spooling down and the injectors still giving more fuel. Feel free to correct me if I'm wrong.

[S14DB]

It may be a vac leak but not the BOV to ATM.

He's blowing out smoke on acceleration and deceleration. Not just on decel when the BOV is venting.

Reason I say timing is because it's still pulling hard. Usually with a vac leak it runs like crap.

[doomviillain]

It may be a vac leak but not the BOV to ATM.

He's blowing out smoke on acceleration and deceleration. Not just on decel when the BOV is venting.

Reason I say timing is because it's still pulling hard. Usually with a vac leak it runs like crap.

right. But wouldnt smoke shoot out during accel because of the rich fuel mixture at the high end? Maybe it just needs a tune up

[ayororo]

I can decellerate in gear and no smoke will come out till the POP happens, and u see it for a bit and then it goes away, so black smoke is only when it pops and when im boostin,

so you guys dont think its internal damage right ? I really dont wanna deal with that I am broke.

Oh yeah and another thing, the cars temp gauge is reading higher than medium for some reason but never goes up to the overheating range,

If i blast the heater it goes down again..

but even if I pop the hood it srsly is not even hot or anything just normal

is that just a faulty sensor? does it relate to blacksmoke etc?

[nissanguy11]

id say no the temperature gauge has nothing to do with the popping.

and like chituntang said it sounds like its just running rich, which is causing un-burn fuel passing through cat, to heat up ignite, and making the popping noise.

[Renelovesnike]

Its a vacume leak!! my friends did the exact same thing whenever he boosted one of his hotpipe/coldpipe cupluers poped off the nipple... haha nipple.. >.< and a buncha black smoke came out the back due to not enough O2 and too much gas ratio =]

the vibrations most likely lossen the T-clams on the cumplers.

but check all of thoze first =]

[ayororo]

Hmmmm thanks guys Im gnna check timing first cause these symptoms
A)Running hotter temp than normal on unless heater is on
B)Gunshot Pop
C)Black Smoke
D)Bad Gas Milage

all fall under the category :/

[Renelovesnike]

I say do the simplest/cheaper/free diagnostics that could fix the problem.. sometimes its little things that dont cost so muchh/time are the problem to begin with.. just my 2 cents =]

[Patrick Bowering]

when I was vented to atmo on stock ecu and maf I would get pops and fireballs when my plugs started to shit out and the backfires got way worse when my injector insulators started leaking. Make a cheap boost leak tester out of a pvc female cap in whatever size your hot pipe is. Just drill and tap a tire valve into it. Glue in the valve with epoxy and just clamp it onto your hotpipe and pressure it up to 15 psi or so and see where it comes out a squirt bottle with some water and dish soap won't hurt either.

[ayororo]

I dont have a presurizer^

Oh and so i looked at my muffler today
And it looks like white/grayish smoke is coming out of the muffler but barely cuz it dissapears
So fast.. This relate to anythin?

[Patrick Bowering]

You dont have a bike pump? buy one or im sure a friend will.

[ModernS30]

I dont have a presurizer^

Oh and so i looked at my muffler today
And it looks like white/grayish smoke is coming out of the muffler but barely cuz it dissapears
So fast.. This relate to anythin?

Isn't it uhm... Cold outside... Have you checked your timing yet? If not, stop posting shit, go check your timing. If that is right, check for a boost leak or a vac leak. If you are good there, check your fuel pressure. You are obviously running to rich. There are no signs of you attempting ANYTHING anybody has told you to try in here.

My stock KA24DE backfires on decel sometimes, I don't get black smoke like you say but my bumper has black on it as well as my muffler. Now my car doesn't have a cat.

Now go try things people told you to try and maybe your car will be fixed faster than if you keep posting on here.

[S14DB]

Isn't it uhm... Cold outside... Have you checked your timing yet? If not, stop posting shit, go check your timing. If that is right, check for a boost leak or a vac leak. If you are good there, check your fuel pressure. You are obviously running to rich. There are no signs of you attempting ANYTHING anybody has told you to try in here.
+1
My stock KA24DE backfires on decel sometimes, I don't get black smoke like you say but my bumper has black on it as well as my muffler. Now my car doesn't have a cat.The KA's stock fuel map has a decel enrichment. This seems to happen a lot when people run cat-less.

Now go try things people told you to try and maybe your car will be fixed faster than if you keep posting on here.
It almost seems like the OP is searching for a cheap and easy solution. Borrowing a timing gun doesn't seem that difficult.

[ayororo]

Its not that i dont want to, i just havent had time.. This weekend i am definitely gnna check it out .. Been studyin for finalls.. It doesnt
Hurt to get more peoples opinions so i know what to check when the time comes ........

K so no it was hot sunny when i could see smoke nd
Sometimes when im stopped i see and smell the smoke on my left side. Coolant level stays
Fine and oil isnt milky but now when i push the car it struggles
To go past 6k rpm, im scared to because after 5k it starts
Blowing smoke and loses power

[yetijeff]

if its reading higher temp than normal that also is and indication that it possibly came out of time....