Black Smoke Under Load~

[R33Turbo]

Hey guys, after getting a cat back exhaust in & BOV recently, i didn't know but the ppl driving behind me goes when i full throttle or even rev it hard in neutral, it gives out black smoke ONCE out the exhaust but not constantly...i think it just gives out black smoke once when i rev it high or gun it under load....

It is running rich correct? cuz i don't have a air/fuel ratio gauge, heard the black smoke was real black someone behind me said but when i revved it in neutral hard it wasn't THAT black but i dunno how it is under load... Is it even normal for the car to run rich with just a cat back exhaust (with stock cat)???? Is it normal for skylines to run rich for safety reasons???

thanks in advanced guys...

[Al]

Sounds pretty normal.

But your 02 sensor could also be faulty; causing the car to use more fuel than it should, thus running excessively rich

[R33Turbo]

Oh is it? cuz it only happens when i do full throttle not when driving normally

[Al]

how many K's do you get to a tank?

when do you fill up: on empty, 1/4, etc?

[R33Turbo]

never full! always been 1/2 and under....most of the time 1/4

Oh KM after fill up? im not sure i haven't estimated...

Edited December 26, 2007 by R33Turbo

[whiter31gxe]

Work out your fuel ecconomy.

Goto a servo and fill your car to the 1st click on the fuel pump

Reset your trip meter

drive about until your down to like 1/4 of a tank

go back to the same servo/pump and refil to the 1st click

look at the bowser and note down the kms

look at how many kms you have done

divide liters by kms then times that result by 100

This will give L/100kms

post that up here.

Edited December 26, 2007 by whiter31gxe

[Al]

Minor correction

Work out your fuel ecconomy.

Goto a servo and fill your car to the 1st click on the fuel pump

Reset your trip meter

drive about until your down to like 1/4 of a tank

go back to the same servo/pump and refil to the 1st click

look at the bowser and note down the Liters

look at how many kms you have done

divide liters by kms then times that result by 100

This will give L/100kms

post that up here.

[Simon-S14]

o2 sensor is not read at full load... its only used to lean out the cruise and idle maps.

Black smoke on full throttle is generally pretty normal... but the better the tune the less wasted fuel there is, if you have a stock ecu hitting rich and retard its going to do it something chronic

[R33Turbo]

o2 sensor is not read at full load... its only used to lean out the cruise and idle maps.

Black smoke on full throttle is generally pretty normal... but the better the tune the less wasted fuel there is, if you have a stock ecu hitting rich and retard its going to do it something chronic

Ill work out the fuel economy...

So your saying its quite normal to run rich with black smoke under full load on stock ecu with JUST A CAT back exhaust? (With stock cat BTW)??

Edited December 27, 2007 by R33Turbo

[Simon-S14]

yes, very common, so rich that afr's can dip into the 10's

[R33Turbo]

Other ppl on the forum says my coilpacks are on the way...would that by any chance affect the reason why i have black smoke under full throtttle??

Cuz im not really happy with black smoke, worst comes to worst an aftermarket ECU would be able to tune it out right?

Also will an aftermarket ECU tune out the BOV causing the bogging??

Wat if its a SAFC?

Edited December 30, 2007 by R33Turbo

[Simon-S14]

if its hesitating when your flooring it, then yeah coil packs could be an issue, otherwise its just good old fashioned skyline richness... either get a power FC or a SAFC and get it tuned by a decent tuner.

[kjb_r33]

o2 sensor is not read at full load... its only used to lean out the cruise and idle maps.

Black smoke on full throttle is generally pretty normal... but the better the tune the less wasted fuel there is, if you have a stock ecu hitting rich and retard its going to do it something chronic

Simon, while this is true, the ECU will make adjustments in closed loop to maintain the correct A/F ratios under cruise, it does also have a bearing on the entire fuel map. The long term fuel trim refers to this adjustment. Fuel maps will be altered based on the amount of trimming the ECU does during normal driving to acheive correct ratio in closed loop. If long term trims are altered say 5% to the rich side, its 5% right through the entire fuel map, not just the closed loop areas. These long term trim adjustments are maintained in the ECU until such time as battery is disconnected and trims are returned to factory settings (0 or BASE). They LEARN this to compensate for alterations to things like altitude, ambient air temp and engine wear, even driving styles.

[Adriano]

Im willing to bet you have put a venting BOV on it, put the stocker back on and 95% sure it will fix your problems and get heaps better fuel economy.

[R33Turbo]

Im willing to bet you have put a venting BOV on it, put the stocker back on and 95% sure it will fix your problems and get heaps better fuel economy.

Yep i have a BOV to dump into air...So how could that affect the black smoke richness? i dun get it....i do have alot of popping sound from the exhaust which i understand if the BOV is the cause but not really the black smoke...BTW i do have coilpacks going but theres no way it'd be the cause of the black smoke under load will it???

Anyway thanx heaps im worried less as skylines are supposed to run rich to be safe.

Edited December 30, 2007 by R33Turbo

[GeeTR]

Yep i have a BOV to dump into air...So how could that affect the black smoke richness? i dun get it....i do have alot of popping sound from the exhaust which i understand if the BOV is the cause but not really the black smoke...BTW i do have coilpacks going but theres no way it'd be the cause of the black smoke under load will it???

Anyway thanx heaps im worried less as skylines are supposed to run rich to be safe.

If the BOV ain't leaking when WOT, it wont effect it.

Rich still inst all that much fun. Over doing it can leave glowing carbon deposits over time. Recommend grabbing something and trimming it out

[Adriano]

" black smoke ONCE out the exhaust but not constantly" Im a bit confused as to when it is blowing smoke. A venting BOV will blow black smoke and make it run rich on gearchanges, as the ECU thinks that air coming out the BOV is going through the motor, so it adds the corresponding amount of fuel. When you change gears it fuels the motor up, then when you accelerate again it comes out as a big puff of black smoke.

Assuming the BOV isnt leaking under boost, it wont make the car blow smoke continuously when under load, just the big puff after a gearchange.

[R33Turbo]

" black smoke ONCE out the exhaust but not constantly" Im a bit confused as to when it is blowing smoke. A venting BOV will blow black smoke and make it run rich on gearchanges, as the ECU thinks that air coming out the BOV is going through the motor, so it adds the corresponding amount of fuel. When you change gears it fuels the motor up, then when you accelerate again it comes out as a big puff of black smoke.

Assuming the BOV isnt leaking under boost, it wont make the car blow smoke continuously when under load, just the big puff after a gearchange.

OHHH~ i get it now... Well u know i heard it was just a big puff of black smoke when i 'double d clutch' so im assuming when i change gears after revving so high in neutral??? also in stationary ive revved it in neutral but it wasn't so much of a black smoke and it didn't seem like a big puff however there was slightly black smoke coming out as it was revved in neutral to like 6000rpm... So??

[Adriano]

Mate, put the stock BOV back on, they are fine for 300rwkw, and work as nissan intended them to.

[GTR-80Y]

Its normal its a skyline. Especially with those stupid blow job valves.