PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

VE value is 0 and LTFT is -10. What's wrong?

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Old Jan 8, 2008 | 08:43 AM
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Default VE value is 0 and LTFT is -10. What's wrong?

I've been tuning the VE today, using RTT, on a 2000 Z28 M6. Disable the MAF, drive for a bit, copy the LTFT over to VE, clear LTFTs, and clear the histogram. After about an hour of doing this, some of the cells are at 0, and the LTFT on that cell was still -10. Is my method incorrect, or am I missing something?

Any help would be great.
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Old Jan 8, 2008 | 10:25 AM
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Please post the tune and a log.
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Old Jan 8, 2008 | 10:33 AM
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Why are you trying to tune VE with LTFT's? Get your self a wideband youll be much happier
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Old Jan 8, 2008 | 11:22 AM
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Not disabling DCFO? maybe?
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Old Jan 8, 2008 | 11:26 AM
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sounds like the maf isnot disabled.

VE set to 0 and in fail mode, the car will shut off.


Ryan
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Old Jan 8, 2008 | 02:07 PM
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I just disabled DFCO a minute ago, and haven't had time to test it out.

I'm a poor college student. $300 for a wideband can buy SO much food and alcohol, it's not even funny

The MAF is in fact disabled. MAF fail frequency = 0.

Anyways, here's the tune. I didn't save the log, so I'll get a new one up when I can.
Attached Files
File Type: hpt
z28_new5_42s-RTT.hpt (457.6 KB, 116 views)
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Old Jan 9, 2008 | 08:55 PM
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disable your long term fuel trims and use the short term fuel trims instead.
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Old Jan 9, 2008 | 09:09 PM
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Originally Posted by mrr23
disable your long term fuel trims and use the short term fuel trims instead.
Make sure long terms are disabled and dfco, and cat converter protection, ect..
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Old Jan 9, 2008 | 09:32 PM
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Hey bro, you're only changing your primary VE table, and you're actually running off the secondary. So, your changes are doing nothing.
Set up your histograms to plot the primary and secondary VEs at the same time.
Also, need to disable LTFT and use STFT.
Injectors? 42 SVOs I assume?
One more thing. I would zero the MAF table, as I'm not sure setting the fail to 0 completely eliminates it. I've never tried just that.
Set your P0101, 102, 103 to no MIL.
May wanna copy over the idle area of the low octane table to the idle spark table, so they are the same.
I think thats about it.
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Old Jan 9, 2008 | 10:09 PM
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On my 04 GTO setting the MAF fail to 0 never disabled it. It had to be physically unplugged.
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Old Jan 19, 2008 | 04:56 PM
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OK update. MAF unplugged, and I used the following tune, and I still have LTFTs of -10 when the VE is zero.

The log is too big to be uploaded. Any thoughts?
Attached Files
File Type: hpt
z28_new5_42s-RTT[1]x1.hpt (457.6 KB, 111 views)
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Old Jan 19, 2008 | 05:01 PM
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You need to

1. disable LTFTs in the editor
2. BEFORE logging ANYTHING, in the scanner, with it hooked up and scanning, reset fuel trims and this will zero them out. If not, it's gonna apply that -10 in the same place it always has, even if it doesn't need it.

Also, as Ed mentioned, make sure to copy everything over to your secondary VE, as that is what you are running off of in SD.
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Old Jan 19, 2008 | 05:37 PM
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You're VE tables were still different. The one with the dip is the primary, and you're not running off the primary, you're running off the secondary.
Also the maf was failed at zero, but I think you still need to zero out the table. So I did.
Try this one. I redid the VE a little bit, and copied it over to your secondary table.
You had a dip in it, but it doesnt look like its in the right place, and the 400 column was too rich.
Load this one, and like frost said, turn the scanner on and reset the fuel trims. I've disabled the long terms. Use the short terms and the histogram to dial in the VE. Or, if you have a wideband, you can use A/F error.
Attached Files
File Type: hpt
z28_new5_42s-RTT[1]x1.EH.hpt (457.5 KB, 128 views)
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Old Jan 19, 2008 | 08:35 PM
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Totally missed the part about the secondary table. I'll load it up and check it out tomorrow.

Thanks guys.
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