Backfiring/popping while under load - Miata Turbo Forum - Boost cars, acquire cats.

ECUs and Tuning Discuss Engine Management, Tuning, & Programming
Sponsored by:
Sponsored by:

Backfiring/popping while under load

Old 05-09-2010, 01:00 PM
  #1  
Senior Member
Thread Starter
iTrader: (4)
 
Join Date: Nov 2009
Location: Toronto, ON
Posts: 1,447
Total Cats: 6
Default Backfiring/popping while under load

Hey guys,

I've got my car running pretty well most of the time. I do occasionally get backfiring and popping while under load in boost. I've already gaped my stock plugs down to 0.030". It seems to happen only when the engine is just warmed up but not driven hard. After a few hard pulls and more aggressive driving it seems to go away. My reading and searching leads me to believe that it sounds like it would be spark blowout. Is my spark too small at this gap? If this is the case, what plug should I be using? A step colder or a step hotter? I'm on the stock spec right now.
dgmorr is offline  
Old 05-10-2010, 09:29 AM
  #2  
Elite Member
iTrader: (2)
 
fooger03's Avatar
 
Join Date: Jan 2009
Location: Columbus, OH
Posts: 4,141
Total Cats: 198
Default

if you had spark blowout, your car would pull like ****, and you'd be able to feel the misfires.

What does your AFR gauge say when this is happening?
fooger03 is offline  
Old 05-10-2010, 09:38 AM
  #3  
Elite Member
iTrader: (24)
 
Join Date: Jul 2007
Location: Cypress, TX
Posts: 3,760
Total Cats: 35
Default

You should be using BKR7E's.
Bryce is offline  
Old 05-10-2010, 09:58 AM
  #4  
Senior Member
Thread Starter
iTrader: (4)
 
Join Date: Nov 2009
Location: Toronto, ON
Posts: 1,447
Total Cats: 6
Default

I just checked and I am using BKR5E.
dgmorr is offline  
Old 05-10-2010, 10:22 AM
  #5  
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,085
Total Cats: 367
Default

5's are too hot. What is your plug gap?
hustler is offline  
Old 05-10-2010, 10:32 AM
  #6  
Senior Member
Thread Starter
iTrader: (4)
 
Join Date: Nov 2009
Location: Toronto, ON
Posts: 1,447
Total Cats: 6
Default

Plug gap is 0.030". I haven't really been driving the car much because I've gotten a bit lazy with fixing the exhaust to frame rattle. I'm gonna get some 7's in the mean time. Does anyone know the new BKR7E part number off hand? I'm searching for it at the moment.

EDIT: Got it here for future reference NGK 4644

Is there any relationship between plug gap and colder plugs? Does a colder plug generally require a smaller gap? Or do these not affect one another?
dgmorr is offline  
Old 05-10-2010, 11:02 AM
  #7  
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,085
Total Cats: 367
Default

That's too much plug gap if you're on the stock coil.
hustler is offline  
Old 05-10-2010, 12:07 PM
  #8  
Senior Member
Thread Starter
iTrader: (4)
 
Join Date: Nov 2009
Location: Toronto, ON
Posts: 1,447
Total Cats: 6
Default

I am on stock coils. What should I be reducing the gap to, 0.025" or even less? I thought 0.030 was what I've seen people recommending. Stock gap is 0.043" isn't it - 1.1mm?
dgmorr is offline  
Old 05-10-2010, 12:32 PM
  #9  
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,085
Total Cats: 367
Default

I had to run .020" when I had the stock 1.6 coils at 16psi or it would blow out.
hustler is offline  
Old 05-10-2010, 01:11 PM
  #10  
Senior Member
Thread Starter
iTrader: (4)
 
Join Date: Nov 2009
Location: Toronto, ON
Posts: 1,447
Total Cats: 6
Default

Thanks, I'll give 0.020" a go on the new plugs. Is backfiring/popping and slight tugging while giving throttle a typical trait of spark blowout? I know there could be a lot of other answers, but everything 'appears' to be ok, so I'm looking for the most obvious answers.
dgmorr is offline  
Old 05-10-2010, 01:30 PM
  #11  
Senior Member
iTrader: (4)
 
Join Date: Jan 2008
Location: Falls Church, VA
Posts: 1,361
Total Cats: 16
Default

Originally Posted by dgmorr View Post
Is there any relationship between plug gap and colder plugs? Does a colder plug generally require a smaller gap? Or do these not affect one another?
There is no significant relationship between the two. I had a bunch of other **** typed out that I deleted, but that's the short answer.
ScottFW is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
brandonbkd
MEGAsquirt
0
09-29-2015 12:52 AM
psyber_0ptix
MEGAsquirt
4
09-22-2015 10:35 AM
emarkey
DIY Turbo Discussion
2
09-05-2015 07:59 PM
Motorsport-Electronics
ECUs and Tuning
0
09-05-2015 09:02 AM


Thread Tools
Search this Thread
Quick Reply: Backfiring/popping while under load


Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.