Page 3 of 3 FirstFirst 123
Results 41 to 56 of 56

Thread: Fuel trims what makes them max out at idle?

  1. #41

    Offline
     
    Name
    Tomasz
    Join Date
    Apr 2015
    Last Online
    22-11-2023
    Posts
    508
    Country
    Other
    Location
    Lodz PL
    Car
    Legumina
     
    The SD mod is about replacing MAF with MAP indeed. Some Evos have a SD / MAP system by default. For some you need a Ceddy ROM mod to add support for SD. In the VR-4 this was implemented by @Kenneth in a special version of his ROM.

    http://www.clubvr4.com/forum/showthr...-based-tuning)

    Not much interest in this mod though so far. As far as pros/cons that I can see:

    Pros:
    - Removed MAF related restriction on intake
    - Open BOV friendly
    - Not bothered by vacuum leaks like the MAF system

    Cons:
    - Complicated to set up due to the need to populate the VE (Volumetric Efficiency) table to even get it working
    - No instant power or economy gains. In fact expect both to be worse before you dial it in.

    Also I reckon that since the SD system can reflect engine load changes much quicker than MAF it will require major tuning in the stock ROM to at the very least remove (or dial down) the acceleration enrichment.
    The more you know, the faster you can go. And I still don't know enough.

  2. #42
    kc427's Avatar

    Offline
     
    Name
    Kenneth
    Join Date
    Aug 2006
    Last Online
    22-03-2024
    Posts
    217
    Country
    Hong Kong
     
    Quote Originally Posted by swinks View Post
    Nope, you still can have vacuum leak between maf and turbo.
    But when I am just cruising, with steady on the throttle, the AFR is normal as around 14.5-15.5. I would guess if vacuum leak will also lean when cruising, but AFR is normal when cruising

  3. #43
    Nick Mann's Avatar

    Offline
     
    Name
    Nick
    Join Date
    Sep 2003
    Last Online
    17-03-2024
    Membership ID
    17
    Posts
    24,895
    Country
    United Kingdom
    Location
    Redditch
    Car
    Legnum type-S
    My Garage
    Visit
     
    Depending on your cruising speed, your vacuum should be less, so the effects of a leak will be minimised.

  4. #44
    swinks's Avatar

    Offline
     
    Name
    Tomasz
    Join Date
    Feb 2008
    Last Online
    21-10-2022
    Posts
    4,578
    Country
    United Kingdom
    Location
    Bourne, Lincs.
    Car
    ex-Galant VR4
     
    As Nick said, due to higher speed of air mass flowing the air leak symptoms will be reduced.
    Also, check out any leaks in exhaust system prior to lambda sensor: manifolds, downpipe, hot side of turbo. This may affect lean idle and good cruise.
    Ex: Galant VR4
    Running 268 HP ATW and 443 Nm torque at 0.9 bar
    Now: Lancer Evolution 8 FQ-300
    Running 325 HP ATW and 510 Nm torque at 1.6 bar

  5. #45
    kc427's Avatar

    Offline
     
    Name
    Kenneth
    Join Date
    Aug 2006
    Last Online
    22-03-2024
    Posts
    217
    Country
    Hong Kong
     
    Suddenly, I am thinking about the oil catch can. It was installed by previous owner, and I have never checked/touched it since I bought the car 7 years ago....haha... maybe it's time to check the oil catch can installation and see any hose problem or not. Or actually, i would like to remove it and back to stock set-up.

  6. #46
    Anderz's Avatar

    Offline
     
    Name
    Anders
    Join Date
    May 2007
    Last Online
    23-10-2020
    Posts
    346
    Country
    Other
    Location
    Finland
    Car
    VR4-19T&Legnum
     
    Quote Originally Posted by Davezj View Post
    Hi anderz
    Can you post up the hz to voltage formula as this could be used as a base for a voltage to hz formula for a MAF to map conversion could it not.

    Or am I think along the wrong lines.

    If you have data point for the hz with respect to the volts, could it be used.
    You know the boost pressure , and the corresponding voltage level could this be converted to a frequency for the into of the MAF signal to the ecu.
    Yes it would be possible to make a SD mod with an Arduino, but guess it is easier to just get the MAP-ECU. The code is really simple, Arduino reads the frequency (50-150 Hz) and outputs linear 1.5V-4.5V based on the read frequency.
    2xTD04L-19T

  7. #47
    Davezj's Avatar

    Offline
     
    Name
    Dave
    Join Date
    Jan 2006
    Last Online
    09-01-2024
    Membership ID
    255
    Posts
    16,245
    Country
    England
    Location
    Manchester
    Car
    VR-4
    My Garage
    Visit
     
    Quote Originally Posted by kc427 View Post
    Suddenly, I am thinking about the oil catch can. It was installed by previous owner, and I have never checked/touched it since I bought the car 7 years ago....haha... maybe it's time to check the oil catch can installation and see any hose problem or not. Or actually, i would like to remove it and back to stock set-up.
    nothing major wrong with the stock oil vapour setup, apart from it will suck oil vapour into the inlet pipe work and it will condense and settle so the turbo inlet pipes and pressurised pipes after the turbo can get a little bit of oil in them. which can look like a turbo seal starting to fail. but it is not, just oil vapour from the block/heads getting pulled through the system when engine is under vacuum conditions.

    Bye for Now!

  8. #48
    foxdie's Avatar

    Offline
     
    Name
    Jason
    Join Date
    Jan 2008
    Last Online
    Yesterday
    Membership ID
    518
    Posts
    5,030
    Country
    United Kingdom
    Location
    Birmingham, UK
    Car
    Silver PFL VR4
    My Garage
    Visit
     
    Just a thought Dave, you say you've come across cars that don't do it, have you either tried their ECU in your car or their ROM on yours?

    I have a spare 7201 if you want it.
    Want your car tuning? Here's my pricing
    Have questions about performance upgrades and ECU tuning? Before PM'ing me, Check this thread first
    Please support CVR4 & become a Full member, you get a full years access to guides, games, chat & much more!

  9. #49
    swinks's Avatar

    Offline
     
    Name
    Tomasz
    Join Date
    Feb 2008
    Last Online
    21-10-2022
    Posts
    4,578
    Country
    United Kingdom
    Location
    Bourne, Lincs.
    Car
    ex-Galant VR4
     
    Quote Originally Posted by Grid View Post
    The SD mod is about replacing MAF with MAP indeed. Some Evos have a SD / MAP system by default. For some you need a Ceddy ROM mod to add support for SD. In the VR-4 this was implemented by @Kenneth in a special version of his ROM.
    There's also Tephra rom with SD implemented from 2010.

    Quote Originally Posted by Grid View Post
    Pros:
    - Removed MAF related restriction on intake
    - Open BOV friendly
    - Not bothered by vacuum leaks like the MAF system
    Quote Originally Posted by Grid View Post
    Cons:
    - Complicated to set up due to the need to populate the VE (Volumetric Efficiency) table to even get it working
    - No instant power or economy gains. In fact expect both to be worse before you dial it in.

    Also I reckon that since the SD system can reflect engine load changes much quicker than MAF it will require major tuning in the stock ROM to at the very least remove (or dial down) the acceleration enrichment.
    Well, it all depends how ****e is your tuner. Not an easy job to get properly balanced maps on flashed stock rom. But once done right you will get much smoother power band and torque delivery. With the same setup and boost level, mapped by the same good tuner, same dyno, I've gained 26 WHP, and 30 lbft torqe. Running maf I've reach full power at 6000 slowly dropping to 7700, with SD I've got full power at 4800 without drop till fuel cut.
    As for fuel consumption, it is all how good is your tuner. I do enjoy on average 330-340 to the tank fill up (45-50 litres) vs. stock being max 250-280 miles.

  10. #50
    swinks's Avatar

    Offline
     
    Name
    Tomasz
    Join Date
    Feb 2008
    Last Online
    21-10-2022
    Posts
    4,578
    Country
    United Kingdom
    Location
    Bourne, Lincs.
    Car
    ex-Galant VR4
     
    Quote Originally Posted by Davezj View Post
    Hi anderz
    Can you post up the hz to voltage formula as this could be used as a base for a voltage to hz formula for a MAF to map conversion could it not.

    Or am I think along the wrong lines.
    Running map sensors mean "manifold obsolete pressure", wherebouts you will find source of that pressure in MAF area?
    Translation of Hz frequency ti Voltage is good if you run alternative managment system which has no such feature and you want to preserve maf features. That's nothing to do with speed density and running map sensors.

  11. #51
    Davezj's Avatar

    Offline
     
    Name
    Dave
    Join Date
    Jan 2006
    Last Online
    09-01-2024
    Membership ID
    255
    Posts
    16,245
    Country
    England
    Location
    Manchester
    Car
    VR-4
    My Garage
    Visit
     
    what i was thinking was using a MAP sensor in the plenum chamber, and conveting that signal to from Volts to Hz and feeding that signal after convertion back to the connector that was plugged into the MAF. i would also have to fit a replacement barometric pressure sensor as that is part of the MAF as well.

    i have not done any research on this topic i am just having thoughts about this subject. It is the comparison between pressure and flow is quite different. i presume the ecu uses many other perameter to difine what state the engine is in. be interesting to look into this topic further

  12. #52

    Offline
     
    Name
    james
    Join Date
    Aug 2014
    Last Online
    15-01-2021
    Posts
    592
    Country
    United Kingdom
    Car
    legnum vr4
     
    There are a few more advantages of map 1 which is very handy.
    If you boost pipe comes off or splits on maf your stuck. Map you can still drive home slowly. Map is far easyer to do mods with as you dont have to worry about where to put things.
    There is a down side that if you have too many sensors from where the map is reading you can get a slight delay signal also a split pipe between manifild and sensor youve had it. Always run just the map sensor on its own this way you only have 1 pipe to check if you get problems.

    On a note about bov why would you want to run a open bov? There rubbish.

  13. #53
    Kenneth's Avatar

    Offline
     
    Name
    Kenneth
    Join Date
    Nov 2004
    Last Online
    12-01-2024
    Membership ID
    NZ002
    Posts
    6,968
    Country
    New Zealand
    Location
    Cambridge
    Car
    Kia Sorento :P
    My Garage
    Visit
     
    Quote Originally Posted by kc427 View Post
    Suddenly, I am thinking about the oil catch can. It was installed by previous owner, and I have never checked/touched it since I bought the car 7 years ago....haha... maybe it's time to check the oil catch can installation and see any hose problem or not. Or actually, i would like to remove it and back to stock set-up.
    Yes, check this.
    There is a pipe that comes from the plenum which IIRC goes into the front cam cover. If you use a catch can and the cam covers are venting externally, then this ends up being a vacuum leak unless plugged up.

  14. #54
    Kenneth's Avatar

    Offline
     
    Name
    Kenneth
    Join Date
    Nov 2004
    Last Online
    12-01-2024
    Membership ID
    NZ002
    Posts
    6,968
    Country
    New Zealand
    Location
    Cambridge
    Car
    Kia Sorento :P
    My Garage
    Visit
     
    MAF and MAP both have benefits and weaknesses.

    The main weakness of our MAF is that it is a low-pressure MAF which sits fairly far away from the plenum chamber. This means that there is latency between throttle plate changing position and air speed changing at the MAF. The ECU needs to be fairly aggressive with enrichment to compensate for this.
    The upside is that they are unbeatable on cruise or steady state throttle. They also allow for air mass calculations which are independent of engine operating variables, catering for changes in intake, exhaust, altitude and other environmental variables which would require a re-tune with MAP

    A MAP sensor sits very close to the valves in comparison so is very good at measuring transient throttle. They are also able to operate without creating a potential restriction in the intake. MAP is also much simpler in terms of the calculations to produce fuel requirements.

    It stands to reason that you could get some gains in fuel economy by having a very tight MAP tune if you are not good at using the throttle gently. The VR-4s seem to use a lot of fuel in accel enrichment so this makes sense.
    However, given a good MAF tune and learning how to use the throttle smoothly can also produce good fuel economy gains.

    So the question is why do you need MAP? I was implementing SD in the ROM and started talking to tuners about it. When I started hearing stories of 700+hp tunes on MAF and how using MAF on pikes peak meant fuel trims stayed correct and no problems with tune I started to wonder why bother?
    Then I started playing with my tune a bit more, aiming at transient response and good fuel trims. My fuel economy went up significantly and throttle response became very tight. Other people with VR-4s were commenting on how just how different my car felt... at which point I lost all interest in SD.

    Ideally of course, you would use a cross over of SD and MAF based on which was going to be better under the current operating conditions... However I don't really think the gains are going to be worth it.

    In my opinion stick with the MAF, tune your injectors (if you have the money, get newer ones which are better technology) to get tight AFRs and ensure good ignition. Then optimise your maps and throttle enrichment. In terms of time commitment, this would be a much better return on investment than thinking about MAP.

  15. #55
    Davezj's Avatar

    Offline
     
    Name
    Dave
    Join Date
    Jan 2006
    Last Online
    09-01-2024
    Membership ID
    255
    Posts
    16,245
    Country
    England
    Location
    Manchester
    Car
    VR-4
    My Garage
    Visit
     
    here is a nice fuel trim video to explain what is going on for one of scanner danners youtube videos.

    it is pretty simple really.


  16. #56
    Davezj's Avatar

    Offline
     
    Name
    Dave
    Join Date
    Jan 2006
    Last Online
    09-01-2024
    Membership ID
    255
    Posts
    16,245
    Country
    England
    Location
    Manchester
    Car
    VR-4
    My Garage
    Visit
     
    Here is another good fuel trim video


Page 3 of 3 FirstFirst 123

Similar Threads

  1. Fuel trims and different type of fuel
    By lateshow in forum ECUs / Mapping
    Replies: 10
    Last Post: 11-07-2013, 10:41 AM
  2. WTB: Door window trims
    By Chris.W in forum UK Parts for Sale / Wanted
    Replies: 3
    Last Post: 28-02-2013, 09:17 PM
  3. WTB: Facelift Legnum Tail light and arch trims
    By rob_d in forum UK Parts for Sale / Wanted
    Replies: 4
    Last Post: 02-06-2012, 03:09 PM
  4. WTB: Face lift wheel arch trims
    By peter m in forum UK Parts for Sale / Wanted
    Replies: 3
    Last Post: 24-08-2011, 11:08 AM
  5. Wheel arch trims
    By wirdy in forum Exterior (Panels, Bumper, Body kits, Lights, etc.)
    Replies: 1
    Last Post: 14-04-2004, 08:32 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •