Diablo wideband tuning problem
08-08-2007, 07:54 PM
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Diablo wideband tuning problem I have a Diablo tune and a AEM wideband. I went out tuning today and it was running at 13to1. So I went in and changed the pe tables from +5 to +8. Then went back out,now running at 13.6to1. WTF. I have ported MAF ends, true duals, ported tb, No cats,and a slp lid. Also tuning for a 125 shot. please help.
08-08-2007, 08:05 PM
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What do you know about your fuel trim (LTFT) situation at WOT?
Depending on how you leave the line, mash or roll it on, you might
enter PE mode from different fuel trim cells and have significant
differences in fuel adders. Tune PE based on a +5 LTFT cell's
result, next time you hit a 0 trim cell you will be lean. MAF ends
are to be suspected of causing positive trimming and the trim
will vary.
Depending on how you leave the line, mash or roll it on, you might
enter PE mode from different fuel trim cells and have significant
differences in fuel adders. Tune PE based on a +5 LTFT cell's
result, next time you hit a 0 trim cell you will be lean. MAF ends
are to be suspected of causing positive trimming and the trim
will vary.
08-09-2007, 06:16 PM
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your right LTFT are at 9 at wot. Short was at 0. can I tune for this or not. the injector slope can be changed to fix it right, or should I get a stock MAF. The trims jump around a little to much though.
08-09-2007, 07:39 PM
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Originally Posted by 02m6
your right LTFT are at 9 at wot. Short was at 0. can I tune for this or not. the injector slope can be changed to fix it right, or should I get a stock MAF. The trims jump around a little to much though.
If these trims are positive, say +5, make a change of -5 to the injector slope adjustment.
Check them again and they should be within + or - 2%.
Now make some WOT runs and note where they are, and add or subtract the difference in the WOT PE range to get them zeroed out as well.
08-09-2007, 08:48 PM
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I don't like fixing an airflow problem (MAF ends ported) with a
fuel delivery lie. Two wrongs might work, but better to fix the
real issue. I would say to get stock MAF ends, descreen them
and see whether you get right with the trims. Minimal difference
in airflow / pressure drop, but put your readings back to true.
Because the MAF is used at varying "weight" in the airflow calc
the contribution of its error will vary, and this is not something
that a single injector slope can compensate (accurately) across
the range.
fuel delivery lie. Two wrongs might work, but better to fix the
real issue. I would say to get stock MAF ends, descreen them
and see whether you get right with the trims. Minimal difference
in airflow / pressure drop, but put your readings back to true.
Because the MAF is used at varying "weight" in the airflow calc
the contribution of its error will vary, and this is not something
that a single injector slope can compensate (accurately) across
the range.
08-09-2007, 09:53 PM
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I say stick a stock, SCREENED MAF back on there. Descreen it and it'll throw off the reading just like the MAF ends you have on it are doing now.
For a bolt-ons car, -5% to the inj. slope across the board is probably a good place to start (as mentioned above). Watching how your LTFT's react at all RPMs will let you know if it's a good spot to be. Ideally, you don't want positive LTFT's. But, you also don't want excessive negatve LTFT's either.
You'll probably need to reduce the PE down to something like 2~3% probably because the inj. slope will affect WOT too.
For a bolt-ons car, -5% to the inj. slope across the board is probably a good place to start (as mentioned above). Watching how your LTFT's react at all RPMs will let you know if it's a good spot to be. Ideally, you don't want positive LTFT's. But, you also don't want excessive negatve LTFT's either.
You'll probably need to reduce the PE down to something like 2~3% probably because the inj. slope will affect WOT too.
08-10-2007, 05:00 PM
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Ok think I almost have it, had to go -10 on the injector slope. At part thottle it runs at -5 and at WOT LTFT's are 0 so are STFT. should they be negative at WOT or not. also air/fuel is at 12.8 now.
