Notices
Tuning Reflashes, Piggybacks, Standalone ECUs

Cobb question

Thread Tools
 
Search this Thread
 
Old Dec 10, 2010 | 10:17 PM
  #1  
Italianjoe1's Avatar
Italianjoe1
Thread Starter
New Member
iTrader: (6)
 
Joined: Dec 2008
Posts: 1,607
Likes: 14
From: Miami, FL
Default Cobb question

I see we can adjust the range that the car uses the knock sensor, anyone know the reason the factory setting ignores it over 6400rpms?
Reply
Old Dec 11, 2010 | 01:53 AM
  #2  
karletto66's Avatar
karletto66
New Member
 
Joined: Sep 2009
Posts: 193
Likes: 0
From: Italy
Default

Also UPREV ignores knock ar high rpm in my info.
May be the ECU si working in that way and is not possible to change with these kind of maps.
Reply
Old Dec 11, 2010 | 02:35 AM
  #3  
0jiggy0's Avatar
0jiggy0
New Member
iTrader: (13)
 
Joined: Aug 2008
Posts: 7,418
Likes: 13
From: Long Island, NY
Default

I believe it was something about engine noise. Where you would be getting false readings.
Reply
Old Dec 11, 2010 | 03:55 AM
  #4  
karletto66's Avatar
karletto66
New Member
 
Joined: Sep 2009
Posts: 193
Likes: 0
From: Italy
Default

Originally Posted by 0jiggy0
I believe it was something about engine noise. Where you would be getting false readings.
May be...
IN UPREV site they have a schematic for a "knock detector" wich take out noise using electronic filtering...
Reply
Old Dec 11, 2010 | 07:11 AM
  #5  
Ziggyrama's Avatar
Ziggyrama
Registered User
iTrader: (15)
 
Joined: Apr 2007
Posts: 1,069
Likes: 1
From: Northboro, MA
Default

The knock sensor is nothing but a microphone that is designed to feed the ECU sound data. The ECU looks at the harmonics and if it sees a particular signature, it will interpret it as knock and act accordingly. If you look at the sound recording of a ping, it has a specific pattern that can be identified by a computer. It's important to note that this is all based on analog signals. So, noise is an important factor. If you get too much noise, the computer will not be able to reliably recognize knock and will likely trigger false positives. Looks like Nissan determined that above 6400 RPMs, the engine makes too much noise and the knock senors becomes unreliable. I would trust this setting.
Reply
Old Dec 11, 2010 | 08:52 AM
  #6  
Italianjoe1's Avatar
Italianjoe1
Thread Starter
New Member
iTrader: (6)
 
Joined: Dec 2008
Posts: 1,607
Likes: 14
From: Miami, FL
Default

I figured it was interference, it just sucks that we can't use it up top. Hoped maybe someone had more solid info, guess i'll just hope and pray for now lol.
Reply
Old Dec 11, 2010 | 09:22 AM
  #7  
Italianjoe1's Avatar
Italianjoe1
Thread Starter
New Member
iTrader: (6)
 
Joined: Dec 2008
Posts: 1,607
Likes: 14
From: Miami, FL
Default

On the same topic, and idea how the timing number in the computer relates to actual advance? I know the car isn't running 38 degrees of advance at WOT...
Reply
Old Dec 13, 2010 | 02:38 AM
  #8  
0jiggy0's Avatar
0jiggy0
New Member
iTrader: (13)
 
Joined: Aug 2008
Posts: 7,418
Likes: 13
From: Long Island, NY
Default

Read the tuning guide. Even the Uprev guide applies. Nissan computers don't calculate using actual timing. They use a theoretical number that represents "burn time" its pretty much 2 points on that system = 1 degree of timing give or take. It isn't exact.

But the gist of it is the higher the number the more timing your running.

You can get some nice seat of the pants gains by upping it 4-5 points from around 4k+ in the last 2 ipw tables.

I wouldnt go any higher then that without verifying it on a dyno.

This of course is guessing your running 93 octane.

There's no real reason to go leaner then 12.5 AF or so on WOT. The VQ seems to like more timing, more-so then a leaner mix, NA at least.

Some people like to go near 13 AF, but that's up to you. All of this should be verified on a dyno of course bla bla.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
XM 1
Engine & Drivetrain
29
Jul 10, 2022 07:44 AM
issyz
2003-2009 Nissan 350Z
6
Jul 2, 2017 03:04 PM
Alexreyes
2003-2009 Nissan 350Z
13
Sep 30, 2015 11:30 PM
Conway_160
Drag
3
Sep 29, 2015 08:07 AM




All times are GMT -8. The time now is 03:55 PM.