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Thread: Can't get the MAF dialed in

  1. #1
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    Can't get the MAF dialed in

    This car is a Corvette '97 with following mods:
    LS6 cam
    Ported heads
    LS6 intake
    LT headers, no cats
    #42 injectors
    Blackwing CAI

    I tuned it first by STFT+LTFT and checked with PLX WB and I got the VE what I wanted. I did this by disabling MAF (MAF fail Hz=1). So the car works fine with MAF disabled.

    When I try to dial in MAF, I get horrible percentage errors thorough the scale both down and up. If I tune it according to %-correction, the next tune may show the same errors in opposite direction. When I sweep through the rpm range in one gear and use the last values per cell, the errors are minimal but in normal driving it still runs rich or lean especially if the pedal is pushed appr. half way.

    I already replaced the MAF with another used unit but still exactly the same behaviour.

    I enclose here the tune and logs with and without MAF.
    Attached Files Attached Files

  2. #2
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    For idle/part throttle tuning disable your ltft learn and PE. Your PE is set to come in really low. This is skewing it. Might want to redial in VE too with these disabled.

  3. #3
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    I already disabled fuel trims and tuned in open loop with no luck but I didn't try with PE=1.

    I think I'll try to tune the VE with PE=1 all around the map and then try again the MAF dialing if you think that's the reason behind my problems.

  4. #4
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    Instead if disabling pe rather set the tps enable to something like 75% surely you won't be hitting that during street tuning

  5. #5
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    I'd rather tune the VE without any PE if I'm going that route. After I have a decent tune, I'd use the PE for quick adjusting the WOT run at dyno if needed (to save some time at dyno). There's many ways to skin a cat...

    I will try this MAF dialing later today and I'll report here.
    Last edited by Tapi; 04-17-2017 at 11:43 PM.

  6. #6
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    Still no luck!!

    I made a tune with 1.17 consistent PE and limited it to only above 80% TPS. I dialed in the VE and after getting that done I started with MAF again.

    First MAF scaling required 50% corrections in some cells. I soon started to do only sweeps through the rpm range in one gear because sudden throttle increases made it very lean. I got the MAF to few percent error through the scale but the curve doesn't seem very nice. Even with this MAF-curve which had only small errors, the car goes lean when you push the throttle a bit harder.

    I disabled the MAF and everything works well.

    Please help me, I must have done some basic mistake... Tune with dialed in MAF curve and couple of logs attached. You can see from WB EQ error that the car doesn't get enough fuel.
    Attached Files Attached Files

  7. #7
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    If this is a manual trans, do your datalog in 4th gear assuming this is the 1:1 gear. If this is an auto, your 3rd gear is probably 1:1. This way you get more steady data. Disable stft and ltft when doing your maf only tune.
    Then find a nice stretch of road and start a roll at around 2500 rpm, start recording your scan and go full throttle in that gear all the way to just before blipping the rev limiter. Rinse and repeat until you get within 0-1% of your 12.0 commanded pe afr.
    Last edited by Matt_lq4; 04-18-2017 at 12:20 PM.

  8. #8
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    I did just that. Many times.

    I have done it in second gear, third gear and fourth also. Yesterday I did it without fuel trims and as long as there's just mild load, I can get smooth MAF correction curve but as soon as the load increases, the same cell goes lean.

  9. #9
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    Quote Originally Posted by Tapi View Post
    I did just that. Many times.

    I have done it in second gear, third gear and fourth also. Yesterday I did it without fuel trims and as long as there's just mild load, I can get smooth MAF correction curve but as soon as the load increases, the same cell goes lean.
    Under power enrichment > engine over temp enrichment > fuel multipier vs rpm, set that to the same eq ratio as your 1.170 (12.5 afr although lower rpm like under 4600 will probably like 1.20 or slightly richer)...either way for tuning sake just make it the same as your pe eq to rule anything out.

    Looking at your 2 scans, your pe doesn't ever come in as commanded lambda stays at 1.00. You need to sweep from around 2500 rpm till basically just before the rev limiter. If the load is too strong for lower rpm then you can always come back in a lower gear to grab the 1000 rpm to 2400 rpm full throttle data.

    Don't forget to log KR (knock retard as you aren't).

    Under ltft, for tuning sake disable it(re enable after if you want), or if no disable button, set min ect to 490 and max to -40.

    Set pe enable map to 70 kpa or so as it should definitely hit at least that at full throttle.

    Lower your pe throttle Hot to 70 in case your tps doesn't read much over 80 at full throttle, again just for tuning sake to tune the maf. Save this as a maf only tune so you don't have to change everything once your done and just grab your maf table and paste it into your regular tune...but we're not done yet.

    Under airflow, dynamic, hi/lo rpm threshold set it to 0.

    In your channel list, make sure you're logging maf airflow (mass airflow rate) and maf airflow sensor (frequency).
    In my tune I have the following however try the following if nothing else is working as I cannot 100% confirm exactly what it will do in your older 97/98 ecu.
    Under engine diagnostics set p0121 error max map to 105, p0121 error min to 0. This is to disable a test as it states in the hp tuner description and says if map is greater than max map, it will use a different tps calculation. This may be your issue as I see a huge 101 kpa map load in your tune but the tps says 60%...you're actually flooring it right?
    Last edited by Matt_lq4; 04-18-2017 at 01:52 PM.

  10. #10
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    Oops just noticed you're already logging the 2 maf channels and I was typing for so long that I noticed other things you mentioned just now.
    Try lambda error in case the afr error causes some issue.
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    Last edited by Matt_lq4; 04-18-2017 at 02:38 PM.

  11. #11
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    Something is going wrong here, your MAF and AE tables both don't look healthy for sure... Hopefully your injector data is right....?

    EDIT: FYI, this is about as bumpy as you want a MAF curve to be: even small errors have a big effect, including at lower rpm. The VE has relatively little effect actually.

    Capture.JPG
    Last edited by dermotw; 04-18-2017 at 10:52 PM.
    99 TA, Texas Speed LS376, PRC heads, 233/239 cam, Fast 92mm, 95mm TB, card style MAF, Tick TR6060, Strange 4.11 12 bolt axle & clutchpack diff, Strano springs/dampers, Vette 18" wheels, Vette disks, CTS-V calipers, 16lb flywheel, long tube headers, no cats.

  12. #12
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    Thank you all for your input! I will continue my quest for functional tune later today but meanwhile a couple of notices:

    1. I had to increase P1514-table to accept more air. Usually I haven't had to do this with N/A-LS1. First I added 20% to the table and even after that I got the P1514 error on while flooring it against brakes. I added some 10% to that and it works. This might give a hint to you more skilled guys/gals of what is wrong here(?)

    2. I get this "disable your fuel trims"-all the time but I'm not so keen to do that. I have found out that tuning with narrowband trims works pretty well and it's safer than without them. I use LTFT+STFT math as correction base so I think those trims will work. After all I made the VE roughly accurate with those trims and my WB agrees to that. After getting the low load dialed in with fuel trims, I change to wideband EQ-error tuning to tune the bigger load areas. I log both ways all the time so I can compare when needed.

    3. If my injector data would be inaccurate, would it affect only in MAF tune?

    4. I'm not tuning by AFR-error. I use EQ-error when I look at the wideband errors. That should be the same as using AFR.

    5. I haven't done anything to MAF-fail trouble code basis. I only put the MAF-fail frquency to 1 so it should be out when I tune it. After all this works fine with maf disabled like this.

  13. #13
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    I checked the injectors and they are "TRE 42lb Bosch Thin Style Fuel Injectors". Would someone please share data for these if available? I'd like to compare if it's the same I used (Green top 42lb data).

    EDIT: This is what I got from the seller:
    There is some lag time data available.

    8V 10V 12V 14V 16V

    1.6ms 1.1ms 0.9ms 0.7ms 0.6ms


    So basically the lag time is 0.7ms at 14v, we do not have complete off
    set tables, it is not a cheap process to get that for all injectors we
    sell. You can extrapolate other information based on the data above
    compared with other injectors. The key thing is to try not run a pulse
    width less than 2ms because we have no way to test on our ASNU machine
    for lower pulse widths.

    Thank You,
    Support
    TREperformance
    Last edited by Tapi; 04-19-2017 at 01:40 PM.

  14. #14
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    I made my own injector data (I know, it's stupid but I'm desperate). I made it using old spread sheet by RedHardSupra (for IFR) and I used those numbers from TREPerformance as base for offset table. After doing that I dialed the VE again and got that more to my liking as a 3d-view. It didn't have as weird shape as before. However the maf problem stayed the same and we got another problem: The car was running pig rich on idle and light load. It was easy to see that when you're in same specific cell in VE, it needed more fuel or less fuel depending on are you coasting or not.

    I returned the Green Top #42 injector data to the tune since it looks like it's working fine with it.

    I'm about to lock my answer to getting it to 1 bar SD COS.

    I enclose here my version of injector data tune and a log made with that.
    Attached Files Attached Files

  15. #15
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    Quote Originally Posted by Tapi View Post
    I made my own injector data (I know, it's stupid but I'm desperate). I made it using old spread sheet by RedHardSupra (for IFR) and I used those numbers from TREPerformance as base for offset table. After doing that I dialed the VE again and got that more to my liking as a 3d-view. It didn't have as weird shape as before. However the maf problem stayed the same and we got another problem: The car was running pig rich on idle and light load. It was easy to see that when you're in same specific cell in VE, it needed more fuel or less fuel depending on are you coasting or not.

    I returned the Green Top #42 injector data to the tune since it looks like it's working fine with it.

    I'm about to lock my answer to getting it to 1 bar SD COS.

    I enclose here my version of injector data tune and a log made with that.
    When you command 1.00 lambda, you're actually getting 0.70 lambda in areas. I suggested disabling trims and tune your ve and maf with the wideband to see if you get any progress because according to your log, what you command for afr and what you get are miles apart.

    Although your lambda error % is so huge that using the trims themselves wouldn't directly relate to the issue in a perfect world, having long tubed headers which means a further back location for the narrowband o2 sensors compared to the factory...isn't helping especially with the delay/switching nature of the narrowband o2 sensors. However your narrowband mV shows very low when the wideband reads very lean so the issue is much bigger than this as at least the narrowbands and wideband agree on when your engine is expelling a lean or rich burn.

    In other areas you're commaning 0.80 lambda and are actually seeing 1.195.
    Start logging KR (knock retard) as you are worried about disabling trims but at the same time have as high as 33 degrees ignition advance at 98 kpa map at full throttle with a lambda of 1.194 (17.5 afr). You may be killing your motor.

    In summary to help you nail down the issues based on outside observation, when you commanded a rich afr, your injectors on both banks showed a LOW pulsewidth indicating that they are being told to "spray very little fuel." So either you are pasting your % error into your tune incorrectly and severely disfiguring your maf and VE, or your injector data is so far off it's to blame. I don't think your injector data would be so astronomically off to be at fault though because when commanding rich, you would still be seeing a richer value than what you're seeing when commanding lean...so you have something 180 degrees backwards..hopefully it's the way you're pasting your error% as that would be a quick fix and I did that once and had a similar nightmare experience as this.
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    Last edited by Matt_lq4; 04-23-2017 at 03:29 AM.

  16. #16
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    When pasting your error, are you selecting multiply by % - half or multiply by %??? If not, that's where you could be causing your issues.
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    Last edited by Matt_lq4; 04-22-2017 at 05:34 PM.

  17. #17
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    I'm using "multiply by %" when I tune the VE but with MAF those error percentages per one cell are so huge and differ from another so much that I make for example -15% correction to 0-7000 Hz and +15 % correction to 7000-up. If I make "multiply by %" to the MAF curve, it's all over the area after that.

    If I look only the wideband MAF error, it commands every time to remove a lot of fuel under 7000 Hz and add a lot of fuel up from 7000 Hz. After making 30% correction there according to log, it require another 30% correction more on my next run. Today I try with stock air filter and see if it makes any difference. I try to use only wideband but without trims I just can't make any WOT sweep through the rpm range because the car will sputter a lot when flooring because it can't get enough fuel.

    I'm logging KR all the time, no worries about that.

  18. #18
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    Success!

    You were right all the time!

    Today I tested with stock air filter and this time I didn't use fuel trims at all. I disabled trims and dialed in the maf by using wideband info only. First by 1/2 throttle because of very lean conditions at some areas. After a while it was possible to do WOT pulls through the rpm range. I used last values from histogram. I replaced the stock air filter box with Blackwing CAI and did the same again.

    After that I did the same for VE and called it a day. I also left LTFT:s disabled since wideband and fuel trims disagreed on lower rpm on light load.

    Thank you all for your help!
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  19. #19
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    Quote Originally Posted by Tapi View Post
    You were right all the time!

    Today I tested with stock air filter and this time I didn't use fuel trims at all. I disabled trims and dialed in the maf by using wideband info only. First by 1/2 throttle because of very lean conditions at some areas. After a while it was possible to do WOT pulls through the rpm range. I used last values from histogram. I replaced the stock air filter box with Blackwing CAI and did the same again.

    After that I did the same for VE and called it a day. I also left LTFT:s disabled since wideband and fuel trims disagreed on lower rpm on light load.

    Thank you all for your help!
    Awesome stuff, I'm happy for your progress on this. Just like many things, when the usual way of doing things doesn't work, try something different and see how it goes. I'm glad it worked out.
    The only reason why I was stressing the Kr is because in your log I didn't see any value under Kr and in my experience, even if there is no Kr present, it will at least show 0.00 if it's being logged. Either way you have it all figured out so that's what matters.

  20. #20
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    Quote Originally Posted by Matt_lq4 View Post
    I was stressing the Kr is because in your log I didn't see any value under Kr and in my experience, even if there is no Kr present, it will at least show 0.00
    Right again. I didn't notice until yesterday. I searched through some WOT logs and found a couple of 1.5 degree lower spark advance areas than the ign table commanded. So I did have knock and for some reason I was missing knock sensor info from channel config. Frightening... I was not prepared that this info would be missing.