MEGAsquirt A place to collectively sort out this megasquirt gizmo

Req fuel constant question

Thread Tools
 
Search this Thread
 
Old 04-13-2014, 01:30 PM
  #1  
Newb
Thread Starter
 
Boostedpos's Avatar
 
Join Date: Feb 2014
Location: Socal
Posts: 24
Total Cats: -3
Default Req fuel constant question

Im confused about the req fuel setting on the engine constants page. I always hear people complaining that it is too low when they are at 7 ms but with my calculations im at 5.8 ms. i read on another thread that on stock injectors you should run 13.2 ms. Am i wrong in assuming with bigger injectors your req fuel goes down? I have a 1.6 turbo running 11 psi and i use rx7 460cc injectors.
Boostedpos is offline  
Old 04-13-2014, 04:14 PM
  #2  
Senior Member
iTrader: (2)
 
Onyxyth's Avatar
 
Join Date: May 2013
Location: Boyertown, PA
Posts: 735
Total Cats: 62
Default

..What?

Set required fuel with the built in calculator and then leave it be.


1800cc or 1600cc x 4 cylinders x 460cc injectors (in your case)

Should be 5.8 or 6.6 depending on 1.6 or 1.8.
Onyxyth is offline  
Old 04-13-2014, 04:41 PM
  #3  
Moderator
iTrader: (12)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 20,650
Total Cats: 3,011
Default

The dead time (injector opening time or injector lag time) has to be set right or your car wont run right with the correct req_fuel. My ms1 had a base map for rx7 460s when I got it and the req_fuel was 7.4 and it ran fine. The reason it ran fine is because the injector opening time was incorrectly set at 1.1 or 1.2 millisecs. The VE map was close and autotuning compensated for the req_fuel and opening times being off.

Opening time on rx7 460s should be about 1.6ms, iirc.
sixshooter is offline  
Old 04-13-2014, 08:25 PM
  #4  
Junior Member
iTrader: (3)
 
furrycurry33's Avatar
 
Join Date: Apr 2013
Posts: 95
Total Cats: 3
Default

Originally Posted by sixshooter
Opening time on rx7 460s should be about 1.6ms, iirc.
Are you positive about the 1.6ms? That goes against everything that I've searched and came up with.. Brain uses 1.2 some other guys go as low as 0.75. I'm currently sitting at this, but couldn't tell you where I actually got them from..
Attached Thumbnails Req fuel constant question-deadtimes.png  
furrycurry33 is offline  
Old 04-14-2014, 08:28 AM
  #5  
Boost Czar
iTrader: (62)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 79,493
Total Cats: 4,080
Default

1.6ms? I idled at 1.6ms.

deadtime for rx7 460cc injectors is around 1.0-1.2ms.




The req_fuel is just a multiplier.

PW = REQ_FUEL * VE * MAP + Injector open time

Req_fuel could be 10 or 5 or 69 for all it matters, so long as the VE table is scaled accordingly.
Braineack is offline  
Old 04-14-2014, 10:26 AM
  #6  
Moderator
iTrader: (12)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 20,650
Total Cats: 3,011
Default

I could be wrong.
sixshooter is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Full_Tilt_Boogie
Build Threads
84
04-12-2021 04:21 PM
lsc224
Miata parts for sale/trade
2
10-01-2015 09:17 AM
MiataGarage
Engine Performance
5
09-29-2015 11:04 PM
itsMikey
MSPNP
3
09-28-2015 06:40 AM



Quick Reply: Req fuel constant question



All times are GMT -4. The time now is 08:38 PM.