P0171 and P0174 codes

[elgineddie]

Hello team,

 

My 2001 K2500 Suburban 6.0L is running rough. Idle is a bit choppy and sometimes the RPMs with dip from 600 to about 400 for a second and then it comes back up. There isn't a SES light but I connected my scanner and pulled P0171 and P0174. Those are System Lean Bank 1 and Bank 2 codes. I cleared it, changed the fuel filter, removed the Hypertech programming and swapped out the Granatelli MAS for the stocker and it's still throwing those codes. I read somewhere that it could be a leaky intake manifold. To try and test it I sprayed carb cleaner all around the intake manifold to see if the engine RPMs would rev or drop. (An old trick someone once told me!) Nothing changed. All coils and plugs are firing and all hoses are tight.

 

I am running outta options for troubleshooting and this truck is starting to really pi$$ me off. I doubt my other bolt-on mods would cause this. I have headers and a FIPK II. ANY help would be appreciated before I shoot 6 holes in the side of it!

 

Thanks in advance!

[budhayes3]

If you can't find a vacuum leak or any form of unmetered air entering, maybe you got a bad load of gas or the fuel pump is starting to poop out. Personally, I'd check fuel pressure next.

[RyanbabZ71]

my impala is doing the same thing

[elgineddie]

Hey Ryan,

I hate to drag this thread on but tell me about the Impala. What year is it and what engine? Do you have any mods on there that you think would create a lean condition? Is your idle whacky? Is it throwing the SES light or are you pulling your codes?

 

Mine is still acting odd. I am back to stock except for the headers and the K&N FIPKII. Haven't had time to measure fuel rail pressures as Bud recommended.

I got the codes this morning, cleared them and it's been OK since then. Maybe it's clogged injectors.

 

As soon as the old lady is back I can pull the snowmobiles out and pull the truck in the heated garage for a bit more troubleshooting!

[RyanbabZ71]

Stock. 3.4 V-6 Check engine light has been coming on. The idle is fine car doesnt run any different

[ken1mod]

Stock.  3.4 V-6 Check engine light has been coming on.  The idle is fine car doesnt run any different

 

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I had same problem, caused by low fuel pressure. I adjusted the regulator described in my recent post to mid of spec. no more problem codes, more power off the line.

 

Ken