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2008 Hummer H3 Alpha codes p0171 P0174

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2 years 6 months ago #52419 by Indskys007
2008 Hummer H3 Alpha codes p0171 P0174 was created by Indskys007
I have 2008 Hummer H3 alpha 5.3L engine
i have codes p0171 and P0174
see pics for fuel trim at idle and 2500 rpm. Just replaced injectors car has 172000 miles all new PCV hoses new MAF sensor. New O2 sensors. Can’t find any vacuum leaks or exhaust leaks. Any help would be appreciated 
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2 years 6 months ago #52421 by Cheryl
Replied by Cheryl on topic 2008 Hummer H3 Alpha codes p0171 P0174
Is it flex fuel? What does the trims go to at 2500 rpm? What are oxygen sensors reading front and rear

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2 years 6 months ago - 2 years 6 months ago #52422 by Indskys007
Replied by Indskys007 on topic 2008 Hummer H3 Alpha codes p0171 P0174
  Not flex fuel
Trim at 2500 is in the attachments
Attachments:
Last edit: 2 years 6 months ago by Indskys007. Reason: Add

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2 years 6 months ago #52429 by juergen.scholl
Replied by juergen.scholl on topic 2008 Hummer H3 Alpha codes p0171 P0174
Long term fuel trim is missing in the 2500 rpm capture, for the greater picture it is important to see this as well....

Did you change the injectors because of this problem or did it show up AFTER replacing them? If the latter make sure they got the correct flow rate.

Did you check the fuel pressure and the fuel volume already?
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.

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2 years 6 months ago #52430 by Indskys007
Replied by Indskys007 on topic 2008 Hummer H3 Alpha codes p0171 P0174
I replaced injectors just because I was doing Valve cover gaskets and I was getting a slow lean to rich code. Intermittently. Haven’t done fuel pressure or volume yet

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2 years 6 months ago #52431 by Indskys007
Replied by Indskys007 on topic 2008 Hummer H3 Alpha codes p0171 P0174
Attached is 2500 rpm
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2 years 6 months ago #52432 by juergen.scholl
Replied by juergen.scholl on topic 2008 Hummer H3 Alpha codes p0171 P0174
A code for switch time refers to the O2's condition......If the lean condition evolved after the injectors were changed make sure they are the correct ones! AZ can be fatal!!!

And yes, test the fuel pressure and volume As well, as you do seem to experience a general fuel delivery problem.
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.

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2 years 6 months ago #52433 by Indskys007
Replied by Indskys007 on topic 2008 Hummer H3 Alpha codes p0171 P0174
12580681 is the injector that came out as well as the ones I installed …
all 4 O2 sensors were changed a few weeks ago with no codes

i will check fuel pressure and volume when my gauge arrives from Amazon 
 

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2 years 6 months ago #52463 by Indskys007
Replied by Indskys007 on topic 2008 Hummer H3 Alpha codes p0171 P0174
Checked fuel pressure 60 drops to 56 when pump shuts off 60psi at idle needle small fluctuations 

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2 years 6 months ago #52465 by juergen.scholl
Replied by juergen.scholl on topic 2008 Hummer H3 Alpha codes p0171 P0174
The pressure is ok...but the volume? In lack of an accurate measuring tool
you may want to install one of the original injectors and do a an balance/pressure drop test comparing to the new injectors.
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
The following user(s) said Thank You: Noah

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