p0174 only

[speedfreak636]

need some help chasing this down please. the car is an 2004 tahoe ls 5.3 swap into my sons 69 firebird. mods modified cold air intake , headers dual exhaust. tried to keep it simple for now. problem is p0174 lean bank 2 its the only code that's happening ltft pegs out at 25. ive check for vacuum leaks twice , cleaned maf , swapped o2s from left to right , checked plugs looked as though its a little richer on 2 , 4 and 6. exhaust smells a little rich but no cats. running into a wall thanks for any help or ideas.

[speedfreak636]

one other question am I running a rich of motor damage with this condition. this problem started after exhaust was installed

[5FDP]

Swap injectors side to side?

Fuel pressure steady at 58psi too?

[speedfreak636]

Swap injectors side to side?

Fuel pressure steady at 58psi too?

swapped injectors over its a flex fuel engine 40 at idle with vacuum 48 with out

injector left to right.hpl

[lukearmstrong1990]

what happens with LTFT disabled so its only STFT.

if you command full open loop does that bank still run leaner?

[5FDP]

The factory fuel pressure on that 2004 Tahoe are suppose to be setup for 33lb/hr at 58psi. If you did not change the flow rate table to represent the new 40psi of fuel pressure that is going to be an issue.


Crank the pressure back up to 58psi, you need it there anyway to get the most out of those injectors. 40psi won't cut it.

[2xLS1]

FP per Alldata.
Fuel Pressure (vin Z Flex Fuel) .................... 335-375 kPa (48-54 psi)

[speedfreak636]

tried replacing regulator no change to speak of on pressure. ordered another today is there another way I can command more fuel pressure? sorry still trying to learn

[2xLS1]

Why people keep replacing the same part that doesn't fix the problem astounds me. Pump has to be able to output higher pressure than regulator is set for.

[speedfreak636]

my pump is a carter p5000 max pressure 75 free flow rate 45 gph. is that not a strong enough pump?

[2xLS1]

I'm not saying that is your problem. But when you change a regulator that is set to regulate at 48-54 psi and the FP is still low, the pump and plumbing is the next logical place to look. I've seen hoses split in the tank with the best of pumps cause low fuel pressure. And I haven't looked at your logs either. If both banks are lean then look for something common to both like FP. If it is only one bank and the other is trimming close to 0 then it is not a FP problem.

[speedfreak636]

if you have time to check them out any advice would be greatly appreciated

[2xLS1]

The log posted in Post #4 is useless for comparing to the log in Post #1. Post #1 log is in closed loop and Post #4 log is in open loop fault with no fuel trimming. But looking at Post #1 log your problem is not fuel pressure. You stated this started after exhaust work was done. I would be looking real close for an exhaust leak by the B2S1 O2 sensor.

[speedfreak636]

2ls1 i owe you a huge thank you and a 12 pack. your idea about the o2 sensor was dead on found 3 pin holes on their welds. and it calmed way down

[speedfreak636]

what do ya think?
after rewelding exhaust.hpl

[2xLS1]

It's still in open loop. Have you changed the tune file from Post #1 to disable closed loop? Reenable closed loop to get LTFT fuel trimming. Ignition timing appears to be really low.

[speedfreak636]

it went into closed loop after it warmed up towards the end of the file