I've been getting some pretty strange PTFTs on what should be a simple tune. My LTFTs were averaging around +4 at cruise/light load, +2-3 at WOT, and +16 at idle. At the time, the intake seemed to be sealed pretty well, but I'm not sure if I was leaking a bit where the TNT ring went on the TB. Tried testing it with carb cleaner, but had no resulting increase in RPM.

At the time, I had a modified PCV with catch can/inline filter prior to the PCV valve. I removed this and went back to stock. LTFTs seemed to decrease a bit, but not much. Could the PCV effect the LTFTs? I've since removed the PCV and went to a vent to atmosphere setup to test it out, but havent had a chance to do any testing. I also removed the TNT ring and put the stock air bridge back on to get as close to a stock setup as possible(minus filter) and then plan to put stuff back on one thing at a time to find the problem. But in the meantine, I'm just looking to get an idea where my problem may be.

Also, just to test the MAF out, I put on a stock 2002+ Z06 maf on and flashed the PCM with the correct MAF tables. Idle jumped to +20, part throttle to +8 and wot ended up going 0 <--- Went back to the stocker.

I cant really see why I'm getting that large of positive results on my LTFTs with my mods(see sig.)

Changes to PCM at time of observation.
STOCK IFR/MAF/Timing(wot area) Tables
Timing at Idle +2 deg
VE x80%,85,95 400-1200rpms
Small changes to idle air/running airflow (Idles and starts great)
COT disabled for tuning purposes
LO timing set equal to HO timing for tuning purposes
IAT vs Load timing all values set to 0 retard for tuning purposes
.25" hole drilled in TB plate

Main Mods:
TR224 112lsa
Kooks 1.75" Headers w/ cats, kooks x-pipe
Borla Stingers
LS6 Intake, LAPD Airbridge, Donaldson Filter, Ported TB
STOCK MAF(Screened) and Injectors
TNT Powerring (seal tested and seems to be good)

Thanks,

Mike

 

PCV if not closed could be a vacuum leak. I think the
IAC will "fight" anyspray testing to the best of its ability
though and you'd want to unhook the servo to make
any idle drop shine through.

The VE table is where the action is, for idle and off-idle
mixture (presuming no unmetered air sources). If you
can run it open loop, fuel-air multiplier of zero (for
example, raise the clsed loop enable temp to something
crazy high and get it warmed up) the O2 voltages will
tell you whether your base tune is lean or rich. You may
need to -increase- VE values away from idle if you see
O2s showing lean. However, headers also can corrupt
the closed loop process when they put the O2s to sleep
and this you would see as occasional idle O2 voltage
"crash and recover" vs the normal, hot, continuous
bounce. So observe the O2s first for such a thing.

 

Didnt even think about raising the enable temp to see what the base tune is at. As soon as I get a bung welded in for the LM-1 this should work pretty well, although I could get a rough idea using the stock 02s.

Right now, in closed loop my 02 sensors seem to still be working pretty good, fast consistant switching with no flat spots(shutting down).

As far as the PCV, I capped off the intake and fresh air tube from valve cover to TB, running a pair of breathers, so it should be entirely separate from the intake air charge. The only way I can see this possibly having any effect on LTFTs would be in a sort of reverse blow-by... sucking air through the breather and into the chamber. But I dont enen know if this is possible.

Thanks,

Mike