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quick question, BANG and black smog!!
https://silviansw.com/forum/viewtopic.php?f=15&t=32076		 Page 1 of 3
Author:  ~bb~ [ Mon Nov 10, 2008 4:06 pm ]
Post subject:  quick question, BANG and black smog!!
Ok the title doesnt really make sense but i don't know how to put it into good words

I put in high octane 98 to start this off.
Ive had a few problems in the past few months, i mean...ill drive and the car will jolt till i rev the shit out of it and a big "BANG" and puff of black smoke comes out the exhaust, which i know is very unhealthy..... but once its gone, the car drives perfectly. by jolting, i mean it almost feels like its having fuel cuts.. it at first happened only on boost, but the last 2 times it has happened when just driving.

Is this the cause of the aftermarket fuel pump? I've just had my fuel filter, oil filter etc all replaced. A friend of mine suggested it may be a filter in the aftermarket fuel pump? I didn't know there is one..

or is it something completely un-related?
ideas please. it doesnt happen all the time, just the past few months, its happened 3 times .. its almost like it builds up to shit then i have to let it go "BANG" and the puff of black smog has to come out...

quickest solution would be great so i can throw it to my mechanic to fix! as i cant show him all the time, it happens out of the blue as i said earlier.

cheers!
Author:  <<Ronin>> [ Mon Nov 10, 2008 4:26 pm ]
Post subject: 
I think that would be un-burnt fuel hitting your hot exhaust, so you're problem is either a breakdown in spark or if you're running an airflow meter an intermitent boost leak.

I had the same problem lately, only when running 1 bar of boost, and after a bit of driving.
I changed the coil packs and haven't had a problem since.
Author:  ~bb~ [ Mon Nov 10, 2008 4:37 pm ]
Post subject: 
ahh cheers Ronin. I haven't even checked the coilpacks since i bought the car!
Author:  oRiCLe [ Mon Nov 10, 2008 4:47 pm ]
Post subject: 
a bang and black smoke sounds alot like fouling plugs...this could be due to coil packs or a slight air leak causing overfuelling...

try starting off with the simplest things it could be...maybe try some soapy water in a spray bottle and spray it on the joints of ur cooler piping and give it a rev n see if any bubbles appear, if you don't find anything maybe try changing the plugs, and cleaning the AFM...then delve into the more expensive parts if none of that solves the problem like coil packs and fuel etc...:P thats what i'd do anyway :P

popping and black smoke is raw fuel, so that would indicate that there is fuel there, just not burining properly...mine used to do it with aftermarket coil packs and incorrect dwell time and older plugs, it would leave a trail of black smoke and stuttering on boost :P

aftermarket fuel pump shouldn't cause any major changes in the way the engine operates unless the fuel pressure reg is not working correctly or something like that...which aftermarket one is it? bosch 040 or walbro or something else?

if u can think of anything that has changed since before it did it, and they are undoable...try that also, it usually ends up being the simplest of things that cause the issues...but when the car has a problem we go looking for big things causing the problem first :P
Author:  ~bb~ [ Tue Nov 11, 2008 8:55 am ]
Post subject: 
Cheers Oricle, i have no idea what fuel pump it is, Michael is going to find out for me.

It may be the plugs. they are Platnum ones (i think thats what its called?) but havent been changed for some time...may just get new platnums and coilpacks... or try your soapy water spray technique!

Im getting it looked at this weekend. Fingers crossed its nothing major
Author:  Mr_G [ Tue Nov 11, 2008 9:53 am ]
Post subject: 
Doesnt sound like anything major.

As others stated, just do the simple check overs as it will more than likely be something oricle stated.

Id be checking:

- Cooler pipes around the silicon joiners
- Hose connections to your BOV
- Clean Plugs
- Clean AFM

I highly doubt its a fuel pump as that is a rarity for it to cause theb"Bang".

If this doesnt solve it, you can try the mechanic option :)

Jason
Author:  ~bb~ [ Tue Nov 11, 2008 11:52 am ]
Post subject: 
yeah for sure.
Could it also be the tune? I did a dyno run on Sat and its running 10 afr which i was just told is running 2 points too rich and can melt pistons FUCK.
Author:  tim200sx [ Tue Nov 11, 2008 12:51 pm ]
Post subject:  hi
I had a similar problem in my s14a check where the dump pipe connects
to the turbo air might be getting in to your o2 sensor so your computer
will be telling it to put more full in which makes it lean out.

Also check the air flow once a mate wanted to be a smart ass and unplug
mine which made it jolt really bad!!!
Author:  ~bb~ [ Wed Nov 12, 2008 9:20 am ]
Post subject: 
Ok, my spark plugs are fine, im running invidual coil packs (i dunno what that means / different that makes) but they're fine too.

haven't tried the soap thing yet! Brad is pretty sure it just needs a re-tune, as its tuned for 20psi and its running on 15 (hence too rich) and hasn't been tuned for over a year.. so its still set for 20.

blah i suck with car stuff. I wish i was more knowledgable!
Author:  i want a silvia [ Wed Nov 12, 2008 9:28 am ]
Post subject: 
20psi on an unopened motor?
Author:  ~bb~ [ Wed Nov 12, 2008 9:36 am ]
Post subject: 
what do you mean by un-opened?

yes it was running on 20 .. he wound it down cause something kept blowing up .. and it was too much strain on a standard turbo?
Author:  i want a silvia [ Wed Nov 12, 2008 12:02 pm ]
Post subject: 
Was the previous owner a habib?

I'm beginning to see a trend here...dodgy wheel studs, high boost levels, etc
Author:  SamBo [ Wed Nov 12, 2008 12:18 pm ]
Post subject: 
~bb~ wrote:
what do you mean by un-opened?

Un-opened, as in, it has standard internals
Author:  badhairdave [ Wed Nov 12, 2008 12:45 pm ]
Post subject: 
~bb~ wrote:
Ok, my spark plugs are fine, im running invidual coil packs (i dunno what that means / different that makes) but they're fine too.

haven't tried the soap thing yet! Brad is pretty sure it just needs a re-tune, as its tuned for 20psi and its running on 15 (hence too rich) and hasn't been tuned for over a year.. so its still set for 20.

blah i suck with car stuff. I wish i was more knowledgable!


I would suggest spending 16 bucks on a set of bkr7e (I think) plugs regardless of how the current plugs look. I suggest a 7 as with 18-20 odd psi you really want to step down a heat range. If you are only going to run 15psi then go the 6 heat range plugs.

All of the above posts contain relevant ideas, but ultimately the most common cause of misfires and rough running are old plugs so change them regardless. Second on the list is boost/vacuum leaks

As far as the tuned for 20psi thing. It's a common misconception that if a car is tuned for 20psi then it is running rich if you run less. This is only applicable if you have maxed the afm or map sensor at 15psi and continued to tune up to 20 (so revs are the only variable).

A decent tune will include light load and partial throttle tunes, as well as a series of different boost settings up to a safe maximum. So conceivably your car was light load tuned with the ebc off (up to say 7psi for example) and then in 2-3psi increments after that.
Author:  ~bb~ [ Wed Nov 12, 2008 1:21 pm ]
Post subject: 
i want a silvia wrote:
Was the previous owner a habib?

I'm beginning to see a trend here...dodgy wheel studs, high boost levels, etc


lol no... his name was frank. if i mention his last name (i wont) im sure someone would recognise him, he's well known on the beaches area. runs his own deli business thats all ill say.

Sambo, yes it has standard internals then, well as far as im aware.. i wouldnt know. i never asked when he sold me the car.

badhairdave, cheers. Ill deffinately get that done then. :) Saturday, while doing the manifold etc! Im assuming i wouldnt have to order the plugs in... would they sell them at usual stores e.g. autobarn, etc?

its not missfiring at all, or running rough, after about 3 - 4 weeks it will all of a sudden jolt till i rev it and let the bang go off and puff of smog. its almost like some dirt is building up then going "bang" and only as of recently.. as its only happened 3 times (first time wasnt that big..2nd two where really bad, car could barely move without jolting..feeling like it wasn't getting any fuel)..

ill adhear to the plugs!
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