darknight

My car is spitting out unused fuel at idle(black mark in garage floor). I smell like I took a bath in 93 octane when I sit still and idle for more than 2 seconds. Is this normal for h/c cars without cats?

OnyxY2KSS

this happens to me at a light with the windows down, but i think i have an exhaust leak

John_D.

iTrader: (2)

My car is running rich at idle too. I have a similar cam, MACS, 85mm maf too. Started a post on it earlier. Advice so far was possibly tune it out using VE. Not sure if that will work or not, closed loop will try to maintain o2 voltages where it thinks they ought to be.

Jorday

my car is the same way
and to be honest with you I'm beginning to get pretty sick of it

wait4me

iTrader: (10)

i will set you guys all up just email me at jessebubb@yahoo.com no more stink, lots more power.

ram-it

Modifying the VE table between 400-1200 rpms solved the problem for me plus I picked up a little power at the strip and cured surging issues on hot starts. That was the first thing I learned and played with when I got HPT. Since I have modified my IFR's, PE and Spark. All this netted me a 3mph increase at the track from one tune to the other. AND no gas me out of the garage smell either.

horist

my car used to reak of gas... and spit out black **** everywhere at idle... then I tuned it you're running rich .. a large cam isn't very efficient at lower RPMs ... just need to do some LTFT tuning

Jorday

I've tried everything in the book, and it does help. It still stinks a little, though.

darknight

Cool guys! Thanks for the knowledge. I will either have the tuner work on this or have wait4me hook it up. My woman doesn't even like to ride in the car now. If that is good or bad, I am not sure.

John_D.

iTrader: (2)

I think this table might be the place to fix it. I'll be experimenting this weekend.
Fuel Control,
Open and Closed Loop Fueling,
O2 Rich/Lean vs. Airflow

These are the stock values (voltages):
366, 436, 436, 436, 457, 491, 501, 457, 457

Those are for airflow values:
0, 2, 4, 6, 8, 10, 12, 14, 16

I believe the 0 and 2 columns are the ones that will impact idle a/f. The upper 5 values are all very near the .5 mark as expected. But the lower flow columns (and colder exhaust) drop significantly. Headers (with more cooling at idle due to the thin walls and more surface area, and with increased distance to the sensor) will report even less voltage at the correct a/f ratio.

Not sure yet how much to tweak them though.

samz28

keep us updated on your find, i'd like to burn leaner at idle. I already did the VE tables but the LTFT's are not all that happy with the results at idle

bomax

iTrader: (3)

I have heard of using TPStoWOT to zero for 400-1200 then using VE table to adjust the idle. This forced the car into open loop at idle.

samz28

does the car still adjust air fuel properly with the MAF in this mode? You then assume the MAF is correct and cannot foul or get dirty right?

99C5JA

I'm having some similar issues. The car smells very rich at idle. Also warm or cold the idle will hunt badly for a minute or so then smooth right out. Another thing I've noticed is that the engine seems to run smoother above 3k. It's almost like you've flipped a switch. I've heard that the LS1 doesn't switch completely to mass air until about then, could this be what I'm noticing? If so is the VE table what I should be looking at (in HPTuners I'm guessing that this is Primary VE vs. RPM vs. MAP)? Which way would you modify the values?

samz28

based on the default values for the stock tune, search for nogo's guide on VE tweaking.

i did something like .7/400 .8/800 .9/1200 on my TUNED tune, on both ve's and then did .9 on the cranking VE and added some timing from 400-1200rpm and the car smells better but without cats you'll always smell some ***. The surging shouldn't happen.

you need to make sure your maf(clean)/o2's good and then run a log/histogram on the ltrims to see how far badly the tune is off at part throttle.