Rich LTFT command

[ForceFedGP]

I currently dont have HPT, just a scan guage (aeroforce)

My 97 l67 seems to be running rich with a -10 to -16 LTFT command at light to steady cruse. I dont know what temp it enters closed loop, my guess is 140* since the LTFT bellow 140 are 7-10, but as soon as it hits 140 it goes pig rich and can feel its down on power. Just wondering what might be causing this. The only DTC I have is for my bank 2 heater circuit since I removed my cat and rear o2. Only mods are a thrasher CAI and a stock 2.5" dp to a 3" mid pipe with a 3" glasspack to the stock 2.25 y pipe.

Possibly related; my #2 cyl has an oil control issue. The plug in that cyl shows heavy unburned oil deposits. On heavy decel (engine brake) and neutral rev bounce (rev limiter) the exhaust has an oil smell. Seperate topic; but that cyl has 150psi and is within 10% of the others (150-165), that show zero signs of deposit. Exhaust shows no sign/smell of oil on morning starts so I dont think its valve seals. Maybe stuck/wore control ring but good compression rings?

[5FDP]

Do you still have the MAF screen on the throttle body and have you cleaned the MAF lately??

No screen and a dirty maf will give weird fuel trim readings. Or it's possible you have extra fuel entering the motor from a leaking injector.

[ForceFedGP]

Do you still have the MAF screen on the throttle body and have you cleaned the MAF lately??

No screen and a dirty maf will give weird fuel trim readings. Or it's possible you have extra fuel entering the motor from a leaking injector.

Have not cleaned it in a year (was thinking I should do that). The screen is there, however it has a minor dent from po about the size of a sharpie. In closed loop I have lean FT's around 5-7, would a leaking inj allow possitive FT's?

I did a leak down fallowed by a wet test last night. My #2 is 160 not 150 like I previously posted. From the results it looks like my short block is in good order. Im hoping my oil issue is a valve seal or intake gasket. I plan to mod this motor as cheap as possible and let it be my test/learning mule for EFI tuning. Mods so far include; xp cam, 140 springs, DR chain, LS7 lifters, 42.5 inj, N* TB, LQ4 maf, ported gen3, 2.8 pulley, FSIC, SD headers. By as cheap as possible I mean not touching the short block or even the heads really, maybe a mild stage 1 blend. Basically the bare minimum to make 370-400whp safely. Still learning the essentials for l67 modding so the list will probably change.

Cyl % Dry Wet

1) 20 150 180
2) 15 160 185
3) 17 150 185
4) 17 165 180
5) 17 165 185
6) 20 152 175

[5FDP]

I figured it was a stock throttle body and MAF still.

So with the changes you made, you'll want to try and re-tune the MAF table in with a wideband and see how close you can bring the trims back in.

[Dr. Nopps]

With the cats punched out & the rear o2's gone and that DTC tripped, it actually sounds like you're running into the "sanity check" certain GM vehicles preform to see if the sensors are being allowed to even do their job. This may also explain the fouled plug(s) without other typical sighs of oil consumption being present. I don't know which years this "check" was being implemented, but without a tuning program to disable those DTC's you could in the meantime try to find a set of o2 simulators. They are usually fairly cheap, really big with the Mustang crowd, and just plug right into the o2 harness.

[5FDP]

I know the 97-00 computers never ran that check. My 2000 never did with headers and catless exhaust.

2001 should have been the first year they started doing it.

[507]

Buy the HP tuner program ForceFedGT, it well be the best thing to do next. Respect to what did to the ride.