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Thread: MAF Relocate Issue

  1. #1

    MAF Relocate Issue

    Having and interesting issue with my MAF relocate(unless this is normal IDK). I placed my MAF about 16" from the throttle body on a 2.5" IC tube. While WOT shifting, right when the throttle body reopens, the MAF reads a spike in air before the turbo spools. I speculate this false reading is happening because the manifold is under a high vacuum and when the throttle plate opens it sucks all the air out of the IC tube and the MAF meters this rush of air and fuels accordingly. Periodically(say 1 of 50 shifts) during a shift event the car will fall flat on its face for a split second from the extra fuel, then resume like normal. Has anyone else encountered this issue? I am guessing the solution is to use the stock size 3" intake tube to create more volume and/or move it a little farther down to roughly 24" from the tb. It is very obvious in the logs, but I want to make sure I am speculating correctly before I revise my MAF location...Also I checked logs prior to relocate and there are no signs of this when the MAF is in the intake tube. Also happens with or with out 5th inj use. I will post a log tonight...forgot my laptop.

    Updated with picture below so you know what to look for and attached 2 logs. look at all the WOT shift points and you see quick maf blip. It happens most of the time but some are not as bad and its usually so quick it is not perceivable while driving.



    The Yellow circle is the maf spike.
    The Red circle is the over fuel.
    The White shows IDC/IPW.
    Attached Files Attached Files
    Last edited by hhrfreek; 07-17-2015 at 05:44 PM.
    Solstice GXP
    6758/E47

  2. #2
    Advanced Tuner
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    I have not relocated my MAF but have read that you do need to keep the diameter at 3" to prevent problems. I'm having a similar issue where the car occassionally falls flat on its face from a dead stop when it is hot outside and the log shows an extremely high VE spike (over 60lb/min) when the MAF shows less than 5lb/min. Also spikes the ETC%, Load% and Injector msec. Cleaned the MAF a couple weeks ago when it first happened and it went away until today. Seems to be connected to high (100F) ambient temps.

  3. #3
    Other than this issue I have not noticed problems from skewing the MAF a bit to compensate for the 2.5".
    Last edited by hhrfreek; 07-17-2015 at 05:50 PM.
    Solstice GXP
    6758/E47

  4. #4
    Anyone with a maf relocate see this at all in their logs?
    Solstice GXP
    6758/E47

  5. #5
    Advanced Tuner Ranger6202's Avatar
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    where is your Blow off located at?
    Custom '85 Crew Cab Short Bed Lq4 swap
    '06 Turbo Vortec Maxx
    '87 Military K3500 LQ4 swap
    '96 K1500 lq4 swap, Howard Cam (216/224 @ .050, .551/.551, 114), Centerforce Dual Friction

  6. #6
    Using stock setup with ZFR.
    Solstice GXP
    6758/E47

  7. #7
    Senior Tuner cobaltssoverbooster's Avatar
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    You should have the MAF in the proper 3" section. That Hair blow drier you put on there is going to cap it out in the smaller tube, the velocity and turbulence in the small could also be causing you these problems.

  8. #8
    Its nowhere near maxing out the maf though. Iirc I'm roughly 2khz or so higher @ WOT and there is still plenty of overhead. I don't get the hair dryer thing is that a zfr bash? I came across a thread a while back where gmtech(probably on the sky forum) put his maf in a 2.5" and it worked properly(it actually appears to be closer to the tb on his setup so maybe it is turbulence). He did mention placement had to be just right...mine must not be. I did it this way because it was super easy/cheap to just use the stock ic tubing. I cut them in half and used an expander to get rid of the factory crimped area and welded them back together. Other than this exact issue the fueling is accurate. I guess when I have time I will make a 3" tube and retune.
    Last edited by hhrfreek; 08-03-2015 at 02:58 PM.
    Solstice GXP
    6758/E47

  9. #9
    Senior Tuner cobaltssoverbooster's Avatar
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    Placement is important but irregularities can be accounted for fairly accurately. Are tuning with a deactivated evap solenoid?

  10. #10
    Yes.
    Solstice GXP
    6758/E47

  11. #11
    Advanced Tuner
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    my MAF is by my pass front wheel, 3" pipe, no spikes, no problems, NA, no snail power here though..

  12. #12
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    Just to put my 2 cents in on this as well. I have done several MAF relocations in charge pipe between intercooler outlet and throttle body. All have been installed with 3" piping, I have not seen any readings being thrown off with it like you are seeing.