Silvia Club of NSW

Why drive when you can drift?
It is currently Fri Mar 29, 2024 10:04 am

All times are UTC + 10 hours [ DST ]




Post new topic Reply to topic  [ 15 posts ] 
Author Message
PostPosted: Wed Aug 31, 2005 12:00 am 
Offline
T28

Joined: Sat May 07, 2005 3:43 pm
Posts: 29
Car: 180sx
hey guys, i have a turbosmart dual port blow off valve on my sr20 and i'm having back firing issues at around 2,000rpm on decel in 2nd gear, it's quite loud when it happens 2. however, when i block the plumb-back line with a clamp the backfiring stops all together, but i also only get a flutter back through the pod filter instead of the blow off valve firing. any1 experienced any problems like this? if so, what are the steps in fixing it, would it be a tuning process? thanks guys, matt.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Wed Aug 31, 2005 9:45 am 
Offline
Moderator
Moderator
User avatar

Joined: Mon Feb 03, 2003 10:19 pm
Posts: 16498
Car: Skoda Octavia RS
Real Name: Iain
i think your best bet would be to remove the BOV, take it apart and clean it and lubricate all the moving parts. its probably getting stuck open, or opening a little on decel. then put it back in a test it again.

_________________
M35 Stagea.info @ http://www.m35stagea.info/


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Wed Aug 31, 2005 5:58 pm 
Offline
T25

Joined: Mon Aug 22, 2005 8:07 pm
Posts: 13
Car: 1994 180sx SR20DET 5spd
Cutting off the plumb back line does not seem like a good idea, as it is likely that that fluttering noise is NOT your pod filter and is in fact the air going back through the compressor wheel in the wrong direction, which will shorten the life of your turbo and in extreme situations can damage the blades leading to imminent failure.

If you MUST run your car this way then I recommend being very gentle when u lift off the throttle (similar to trying to silence a fully-venting bov when the cops are around) as when u lift off hard, ur inlet suddenly experiences vacuum conditions and the air will, as mentioned before, be sucked very hard back up the piping and through the turbo in the wrong direction, causing that 'fluttering' sound. I agree, however, that this sound is quite nice. The fluttering sound, on the other hand, can be caused by your BOV not flowing enough air..


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Sep 01, 2005 6:27 pm 
Offline
T28 Hybrid

Joined: Mon Aug 01, 2005 11:51 am
Posts: 75
Car: 180sx ca18det
i have the same problems,

i just fitted a BOV to my ca18, it never backfired b4 now i have the same problem, mine happens wen the turbo spools up but i dont use all the boost, i shift at like 4k or sumthing.

i can understand the BOV getting held open but how does this explain the backfire??

all i can think of is that its loosing boost so its not getting the right air/fuel ratio.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Sep 01, 2005 7:44 pm 
Offline
Moderator
Moderator
User avatar

Joined: Mon Feb 03, 2003 10:19 pm
Posts: 16498
Car: Skoda Octavia RS
Real Name: Iain
another thing is that they could be externally venting BOVs, that will make the car run rich when it vents to the atmosphere. thus making the car think there is more air than there actually is. more fuel with less air makes it more rich, and backfiring will occurr because the fuel ends up in the exhaust

_________________
M35 Stagea.info @ http://www.m35stagea.info/


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Sep 01, 2005 7:47 pm 
Offline
T28

Joined: Sat May 07, 2005 3:43 pm
Posts: 29
Car: 180sx
so it couldn't be anything 2 do with tuning air/fuel or anything like that. the majority of the time it happens is when she's warm. i've been told 2 put a restrictor in the plumb back line, so i tried a couple of small hose connectors 2 decrease the flow, even thought of putting a smaller diameter plumb back line on, but somehow, i think it's not gonna help. i think its a failry clean bov, i've had troubles with it since new, even tried contacting turbosmart, but i was just sent the install instructions, and it's installed exactly 2 specs...


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Sep 01, 2005 7:54 pm 
Offline
T28

Joined: Sat May 07, 2005 3:43 pm
Posts: 29
Car: 180sx
hey zei20l, that does make sense, maybe a power fc could help my problems, it's a good excuse 2 buy 1 anyway!


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Sun Sep 04, 2005 5:01 pm 
Offline
T03 Hybrid

Joined: Tue Jul 23, 2002 5:20 pm
Posts: 190
Location: sydney
Car: CA18DET Datsun 1200
This is an MAFM + atmo-venting BOV problem.

So Zei20L has got it right.

The standard Nissan ECUs rely heavily on the MAFM signal to determine how much fuel to add. If a big volume of air "goes missing" from the intact tract via a BOV, then it will overfuel. It's that simple.

The flutter noise is the turbo "copping abuse", a cheap or mistuned BOV will also make this noise occur.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Sun Sep 04, 2005 8:37 pm 
Offline
T28

Joined: Sat May 07, 2005 3:43 pm
Posts: 29
Car: 180sx
i think since the plumb back line is blocked off, it creates a pressure lock at the top of the bov piston and the pressure in the intake can't physically push the piston up 2 release the pressure, so therefore it reverts back 2 the turbo. i no it's not good 4 it... but the back firing at times causes my car 2 stall. its at decel usually stopping quickly, the rpm dropping real quick, eg having the revs at 4,000 and pushing the clutch in. i think once a power fc goes in, i think the fuel curve on decel at low rpm needs adjusting, i got a feeling that'll solve the problem. thanks guys.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Sat Sep 17, 2005 6:24 pm 
Offline
Quad T51

Joined: Fri May 23, 2003 10:05 am
Posts: 2411
Just get a plumb back blow off valve or plumb back your existing bov, they sound pretty good anyway.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Sun Nov 26, 2006 9:46 pm 
Offline
T03 Hybrid

Joined: Tue Oct 24, 2006 11:11 pm
Posts: 161
Location: Narrelan NSW
Car: 94 180sx street, 93 180sx track project
Real Name: nick
i got a turbosmart bov to on a ca, i cant say i hav any backfiring, but i did get a slight enriching, with then fluttering, i got this to at realy row rpm but seeing my bov it spring rate adjustable, i set it really soft and it is minimal, so just find a place that can do a new SOFTER spring or just run more boost


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Sun Nov 26, 2006 11:55 pm 
Offline
Moderator
Moderator
User avatar

Joined: Mon Feb 03, 2003 10:19 pm
Posts: 16498
Car: Skoda Octavia RS
Real Name: Iain
thats because its a CA, enough said.

_________________
M35 Stagea.info @ http://www.m35stagea.info/


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Sun Dec 31, 2006 1:11 am 
Offline
T03 Hybrid

Joined: Tue Oct 24, 2006 11:11 pm
Posts: 161
Location: Narrelan NSW
Car: 94 180sx street, 93 180sx track project
Real Name: nick
hey hey hey there aint nuffin wrong with da good old ca's, so far shes been good for me n ive killed many sr20s goin around out this way


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Sun Dec 31, 2006 9:12 am 
Offline
Moderator
Moderator
User avatar

Joined: Mon Sep 08, 2003 11:21 pm
Posts: 5731
Location: Sydney
Car: WGNC34,S14,AE86
then they weren't trying,or couldn't drive.

don't go too soft on a BOV spring,as you'll then get idle problems as it'll suck false air through the loose valve diaphragm,particularly if you're running a cheap atmo BOV.

I used to get occasional backfiring on my GF's S14 when it had a turbosmart atmo BOV fitted,regardless of how it was setup. there's a trust type R on there now,and while it does flutter a bit more than before,the idle is more stable and there's no backfiring anymore since it went on.


Justin...

_________________
STI - Made in Texas,not Japan.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Jan 02, 2007 9:13 am 
Offline
Token Old Guy
User avatar

Joined: Thu Jun 16, 2005 5:09 pm
Posts: 2849
Location: At my desk
Car: 180SX
watto wrote:
hey zei20l, that does make sense, maybe a power fc could help my problems, it's a good excuse 2 buy 1 anyway!


Good time to buy a Haltech that uses a MAP sensor then you can run your atmo BOV without back firing or puffs of black smoke on decel :D

I was at Adams the other day when he had a car on the dyno with a PFC and an atmo BOV. Everytime it would spool down after the power run it would backfire after it idled right down and puff of black smoke.

Curious as to why it was doing this I asked Adam he said it does it on most AFM / atmo BOV cars.

_________________
I didn’t break it, I just modified the operational status...
There are 10 types of people in this world, those that understand binary, and those that don't.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 15 posts ] 

All times are UTC + 10 hours [ DST ]


Who is online

Users browsing this forum: Google [Bot] and 22 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group