+18 ltft at aidle

[keving]

I have done some searching, but nothing specific to my issue:

I have tuned my LTFT's to around -4 to 0 using the maf calibration (airflow vrs frequency) table, the only one that will not come down is idle at 0 mph, these stay at about +15. How can I lower this?

[jimmyblue]

First determine whether this is a real short fueling
(short airflow reading) problem or a feedback
problem (lame O2s; headers?). Idle airflow reading
involves mostly the speed density tune (VE) with
only a small MAF contribution. If you take the VE
table and (say) scale by 0.9 in the 400, 800 columns
and see the trims move down by 10, you have VE
authority. If they don't move much then suspect
the O2s are just asleep at the wheel. You already
know you have no MAF authority there.

[keving]

Wow, that actually makes sense. I don't have headers, so I will make the changes in my VE. When does it use the Primary table, and when does it use the secondary table? Should I make the changes in both tables?

[S2H]

just make the changes in both...
make changes in primary table..copy appropriate lines over to teh secondary table as you go...
SD uses teh seconday unless yo have an SD os(1/2/3 bar)

[keving]

Cool, I'll make the changes and check it out...thanks guys, quick and helpfull as always.

[jimmyblue]

You don't need to go straight SD mode to test this out,
just change the low end of the table and check the
response (LTFTs will slowly follow what the STFTs do).
You're only testing for sensitivity, at this point, to know
what the sore spot really is.

I know in idle tuning for me, on a stock-setup car, the idle
trims responded nearly 1:1 to any VE table change.

Anyway if the car is in stock configuration (MAF hooked
up and enabled) you can just mess the Primary table
around. The Secondary is used for fault modes (one of
which, the SD enthusiasts use to get full time speed
density operation). You will want to keep the Secondary
in step or, if you were tuning in speed-density-only mode,
vice versa. Here an Excel sheet set up to decimate the
Primary and make Secondary, or interpolate Secondary
to make a full Primary, is a handy widget. I bet some of
the tuning spreadsheets out there contain this as a tool.

[keving]

I don't think this is working, I scaled 400 and 800 by .90 %, drove around for about 40 miles, no change, then scaled, 1200 by .9, 800 by .92 and 400 by .95. no change in my ltfts.. any ideas?

here is my current ve;
27.54650 33.40577 40.84863
29.96939 35.60696 44.64924
32.40019 38.09319 50.35015
35.63863 40.56359 51.30031
37.26181 42.22635 53.20061
38.87707 43.88912 54.15076
39.68469 45.53605 55.10092
40.50816 46.37535 57.00122
41.30787 46.37535 57.95137
44.54631 48.02228 57.00122
45.36185 48.85366 57.95137
46.16948 49.67713 58.89361
46.97711 50.50851 59.85168
47.78474 51.33198 60.80183
48.60029 52.16336 61.75198
50.21555 52.99474 63.65229
51.84664 55.48098 65.54467
53.46190 57.13583 67.45290
53.46190 57.13583 67.45290
my original one:
33.99962 40.34980 43.00231
37.00051 43.00231 47.00087
40.00141 46.00321 53.00266
43.99997 48.99619 54.00032
46.00321 50.99942 56.00356
47.99853 53.00266 57.00122
48.99619 54.99798 57.99888
50.00176 56.00356 60.00212
50.99942 56.00356 60.99978
54.99798 57.99888 60.00212
56.00356 58.99654 60.99978
57.00122 60.00212 61.99744
57.99888 60.99978 63.00302
58.99654 61.99744 64.00068
60.00212 63.00302 64.99834
61.99744 64.00068 67.00157
64.00068 67.00157 68.99689
66.00391 68.99689 71.00013
66.00391 68.99689 71.00013