NefMoto > Technical > Tuning > Fuel Trims via MAF curve dial or Injectors Factor??????
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Author Topic: Fuel Trims via MAF curve dial or Injectors Factor??????  (Read 13701 times)
Dropout
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« Reply #15 on: February 24, 2015, 12:24:52 AM »
I don't think deceleration will be a big issue since on decel. your on "overrun"  down to a given rpm.  Checked the logs currently my idle load is ~ 0.90ms, deceleration load is ~0.50-0.55ms, this is with the current set up and load (KHFM) scaled down by %12 (will pull the stock loads from the laptop tonight) . BTW I also lowered the load threshold in the TLRAN tables, as I understand these are the closed loop lambda control threshold .

P.S. One thing that I've noticed is that g/s no longer mach the hp using the g/s / 0.8 formula, my g/s are a lot higher , do you have the same effect ? 
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eliotroyano
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« Reply #16 on: February 24, 2015, 05:50:37 AM »
Quote from: Dropout on February 24, 2015, 12:24:52 AM
I don't think deceleration will be a big issue since on decel. your on "overrun"  down to a given rpm.  Checked the logs currently my idle load is ~ 0.90ms, deceleration load is ~0.50-0.55ms, this is with the current set up and load (KHFM) scaled down by %12 (will pull the stock loads from the laptop tonight) . BTW I also lowered the load threshold in the TLRAN tables, as I understand these are the closed loop lambda control threshold .

P.S. One thing that I've noticed is that g/s no longer mach the hp using the g/s / 0.8 formula, my g/s are a lot higher , do you have the same effect ? 

I also have to tweak down TLRAN values for close loop control. Inclusive TLRAN at high RPMs depends a lot in turbo spool up behavior, needing to down it considerably. Mine is ball bearing and practically jumps from vacuum to almost full boost instantanealy.

Ok anyway about MAF values, I also notice a little high gr/s values with VR6 MAF housing only. But due to some weird behavior I have notice sometimes at idle and around it (idle jumping / hunting, worse with AA sometimes - I also check for leaks.) I switch to complete VR6 OBD1 MAF to completely match MLHFM values.

I have studied both curves ( VR6 MAF housing - linear scaled -  and complete VR6 MAF) and I notice that it give us a little more resolution at high boost (high gr/s values) but it is not precise at all at low values (idle) for example. With complete VR6 MAF I have seen MAF values up to 223 gr/s @ 18psi max with GT28 turbo not totally tuned. I don't know if with complete MAF, g/s / 0.8 formula applies.
« Last Edit: February 24, 2015, 05:58:07 AM by eliotroyano » Logged
Dropout
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« Reply #17 on: February 24, 2015, 07:35:16 AM »
Interesting, I have rock stable idle, like oem. Whats your idle load ? Is the AFR correct? At one point I had a bit of hunting idle which was due to a lean mixture and the idle adaption hitting the limit, after enriching the mixture everything got back to normal . Also check the plastic tube going from the plenum to the brake booster, mine was cracked and was loosing pressure, took me a week to figure out why the car was throwing an error (checked all the other hoses and so on, even looked at this tube, but the cracks where on the bottom), finally found out the hard way when it broke off, good thing I was on an empty road .

P.S. have you changed the ignition timing at idle, it can also lead to hunting .
« Last Edit: February 24, 2015, 07:38:41 AM by Dropout » Logged
eliotroyano
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« Reply #18 on: February 24, 2015, 08:08:05 AM »
Quote from: Dropout on February 24, 2015, 07:35:16 AM
Interesting, I have rock stable idle, like oem. Whats your idle load ? Is the AFR correct? At one point I had a bit of hunting idle which was due to a lean mixture and the idle adaption hitting the limit, after enriching the mixture everything got back to normal . Also check the plastic tube going from the plenum to the brake booster, mine was cracked and was loosing pressure, took me a week to figure out why the car was throwing an error (checked all the other hoses and so on, even looked at this tube, but the cracks where on the bottom), finally found out the hard way when it broke off, good thing I was on an empty road .

P.S. have you changed the ignition timing at idle, it can also lead to hunting .

Thanks a lot for your interested Dropout. Take a look --> http://nefariousmotorsports.com/forum/index.php?topic=7443.0. This jumpling/hunting idle occurs sometimes only, specially after DTCs clean or after ECU reflash. Normally AFRs at idle are from 14.8 to 14.2, sometimes can be from 15.2 to 13.9. . Generally idle is really stable. LOAD at idle and engine hot are around 0.9-0.95ms.
Ignition timing at idle (maps) was not changed, it is OEM 12° at idle. Also trims are -0.8% / -0.8% all around.
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Dropout
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« Reply #19 on: February 25, 2015, 05:43:10 AM »
I'll take a better look at the log tonight, but one thought, maybe the injector spray pattern its not correct which could cause this problem ? Have you tested with other injectors with a different spray pattern, maybe one close to the stock injectors ?
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eliotroyano
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« Reply #20 on: February 25, 2015, 07:00:39 AM »
Quote from: Dropout on February 25, 2015, 05:43:10 AM
I'll take a better look at the log tonight, but one thought, maybe the injector spray pattern its not correct which could cause this problem ? Have you tested with other injectors with a different spray pattern, maybe one close to the stock injectors ?

I am using Genesis 415cc injectors.
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