Blowing Black Smoke On Boost

[GTR6]

Hey guys,

my first post here on the forum, but have been reading a lot over the past 6 months..

recently purchased a 32 gtr, 125k on the clock. Pretty much stock except for a 3.5" cat back.

when I first purchased the car, it naturally blew a small amount of black smoke on boost, back fires regularly on engine breaking etc.. what you'd expect. I've recently noticed its blowing a lot more black smoke, back fires about the same amount. I think it might be running rich? I know the previous owner used 95, I always use 98, not sure if this is contributing to the problem.

Before I purchased the car, I checked the oil.. he had recently changed it as it was still quite golden. Its now done about 3000k and is a little black, could this be related in anyway? I'll be changing the oil out this weekend with some 300v.

If anyone is able to shed some light on how I might go about diagnosing/fixing this, that would be appreciated.. and if its not even a problem, let us know..

Cheers

[The Mafia]

Its not really a problem... But the reason is simple - Its running rich. Get an aftermarket ECU and tune it to better suit Australian fuel and conditions.

In Japan, the air is always more cold, and the fuel has a much higher RON rating.

THeir ECU was never meant to work properly here.

An aftermarket Powerfc should cost barely $1k. If you cannot afford it, then you cannot afford a GTR.

[MrStabby]

An aftermarket Powerfc should cost barely $1k. If you cannot afford it, then you cannot afford a GTR.

Or try Nistune instead. Cheaper, looks stock and its an Australian product. However since the car appears to be blowing more smoke without any changes you may have an issue with an AFM or other sensor. If you have any mates with Consult cable+software check the ECU fault codes.

Dont worry about the oil going black - that's normal and not related. If there's good oil in there already change it at 5000kms, if you don't know what it is then yeah change it now.

[Dose Pipe Sutututu]

completely normal, when it starts blowing white smoke that's when you need to be concerned

[GTScotT]

ur probably up for a full service mate. try changing ur spark plugs next time u do the oil, and clean ur AFMs with some electronics cleaner. o2 sensors are also only a 60k item, so in theory your car should be on its 3rd set.

I personally would not advise reverting to retuning the ecu if its not running right to begin with. despite the conditions and tune differences the JDM ecus dont run that mega rich as a result.. you should be able to get it back to a reasonable state where the tune is only not 'optimum' but still good just by doing general maintenance.

I recomend the above maintenance before you make any substantial changes to the car.

[The Mafia]

Sorry about my half assed reply too mate. Just got off a 20 hour flight. Pretty messed up lol.

These guys are right - Get the service done. Plugs, AFM, air filter, oil change, fuel filter etc.

But at the end of the day, the ECU was never meant for Australia.

The Nistune board is also a great option. I should have mentioned it earlier too.

[GTR6]

cheers guys.. I'm going to do the full service and see how that goes..

my plan is to do a few mods over the next 6 months, so was always planning on changing the ECU and having a tune done once thats complete.

thanks heaps for the help

[West]

completely normal, when it starts blowing white smoke that's when you need to be concerned

......or blue !

[Tough33]

Probably just over fueling

[GTR6]

Just changed my oil, now using Motul 300v.. the car is now running a lot better. No idling issues and its not blowing nearly the same amount of smoke, almost back to normal in fact.

I will be changing my air intakes over the next couple of weeks, just looking at some apexi's on: Nengun - does anyone know a better place to buy these?

The other thing I wanted to know is where to buy an o2 sensor? is it recommended to buy a genuine nissan one and wear the price tag?

[clip14]

have you tried an ECU reset as well? some nissan ecu's have a self learning feature which adjusts the fuel mixture.

you can get aftermarket o2 sensors. is your ecu throwing an o2 sensor error code to replace the sensor?

if you're thinking of paying out for a genuine o2 sensor, look into wideband o2 sensor replacements. you may be able to score an aftermarket wideband o2 sensor and controller, which have outputs to support the standard ecu and narrow band o2 sensor outputs.

[GTR6]

I'll try resetting the ECU tomorrow night.. I'm not sure how to read the error codes though, I'll need to read up on this.

See how this goes, otherwise I'll take your advise and look into buying a wideband o2 sensor.

Cheers for your help _b

[Marcus89]

Just changed my oil, now using Motul 300v.. the car is now running a lot better. No idling issues and its not blowing nearly the same amount of smoke, almost back to normal in fact.

I will be changing my air intakes over the next couple of weeks, just looking at some apexi's on: Nengun - does anyone know a better place to buy these?

The other thing I wanted to know is where to buy an o2 sensor? is it recommended to buy a genuine nissan one and wear the price tag?

I don't see changing the oil having any real effect on the smoke produced from over-fueling. Sure it wasn't just a placebo effect or is your car burning oil as well?

[PM-R33]

You could probably capture the black smoke that comes out of my car on boost and use it to run another car

[Nee-san]

You could probably capture the black smoke that comes out of my car on boost and use it to run another car

LOL... + 1

[silviaz]

My mechanic said that black smoke on boost is completely normal even with aftermarket ecu and tune, is this right? Sounds way off to be. Sure it's common because people don't tune their cars but from my understanding if you're popping flames or blowing a lot of black smoke, you're running way to rich? He was saying actually that you want to run very rich when boosting. Though a tuner told me you shouldn't have black smoke on acceleration only on deceleration. My spark plugs only last a few thousand km I noticed before my car started running rough, but now runs fine when putting new plugs in.

 

Most cars that I've seen boost hard have never had black smoke on acceleration.

Edited April 15, 2024 by silviaz

[Dose Pipe Sutututu]

9 minutes ago, silviaz said:

My mechanic said that black smoke on boost is completely normal even with aftermarket ecu and tune

ever seen a stock Evo with a 4G63T and just a high flow cat & cat back on boost? It's a smoke screen!

[GTSBoy]

18 minutes ago, silviaz said:

He was saying actually that you want to run very rich when boosting.

He's dumb.

The exact mixture you need to run will depend on the specific motor (some will need more fuel than others, because some are knock resistant and others like to knock), the fuel (if you were planning to run on 91 you would inevitably end up with lower lambdas than if you were planning to run on 100), the boost target, the state of modification of the engine (ie, has it got higher or lower compression than it did stock, has it got big cams causing you to bleed off effective compression outside of the cam's efficiency peak, etc etc???) and a number of other things. Having said that, for a given combination of the above it might be very sensible to be aiming for say, 11.5:1 in the middle of the torque peak. That is pretty rich, but not "very rich". Very rich is (obviously) richer than that. Stock Nissan ECUs liked to push the mixtures down to ~10:1 when they got run out of their comfort zone. That's defo black smoke territory, but still not smokescreen territory.

TLDR: he's dumb. The motor will be given what the motor wants, and that is not always "very rich".

[silviaz]

22 minutes ago, GTSBoy said:

He's dumb.

The exact mixture you need to run will depend on the specific motor (some will need more fuel than others, because some are knock resistant and others like to knock), the fuel (if you were planning to run on 91 you would inevitably end up with lower lambdas than if you were planning to run on 100), the boost target, the state of modification of the engine (ie, has it got higher or lower compression than it did stock, has it got big cams causing you to bleed off effective compression outside of the cam's efficiency peak, etc etc???) and a number of other things. Having said that, for a given combination of the above it might be very sensible to be aiming for say, 11.5:1 in the middle of the torque peak. That is pretty rich, but not "very rich". Very rich is (obviously) richer than that. Stock Nissan ECUs liked to push the mixtures down to ~10:1 when they got run out of their comfort zone. That's defo black smoke territory, but still not smokescreen territory.

TLDR: he's dumb. The motor will be given what the motor wants, and that is not always "very rich".

Yeah, I think I keep getting bad advice. I'll get a tune from a reputable place (from the place that they said black smoke on acceleration is not normal and hopefully it's fixed.) That one place I went to initially told me that they do run the car slightly on the rich side for safety.

Edited April 15, 2024 by silviaz

[silviaz]

35 minutes ago, Dose Pipe Sutututu said:

ever seen a stock Evo with a 4G63T and just a high flow cat & cat back on boost? It's a smoke screen!

Evo's now that you mention it do tend to stink I've noticed lol but don't remember smoke. Is that taking into account a properly tuned aftermarket ecu?