I have a 08 Hummer H3 with a L5 I'm having issues with with bank 1 running lean I've replace both oxygen sensors catalytic converter mass air flow sensor fuel injectors coil packs spark plugs after replacing all that my engine light stayed off for 3000 miles but now it stumbles on Startup to almost cutting because I have gotten since this started again are p1174

 

I also have codes u1017 p0300 p171

 

Welcome to HF. From this point forward, please avoid posting duplicate threads, as in do not do it again. Post your question once and patiently wait for responses. That is how we do it here.


If you did all the stuff you mentioned because of a lean condition, you did a lot of extemporaneous work.


When was the last time you cleaned the Throttle Body? When was the last time you changed the air filter?

Check your intake for leaks. Confirm that all the intake manifold bolts are tight to torque specs. Common problem, they vibrate loose and create a leak downstream from the MAF.

 

I took the throttle body off and cleaned it spotless. The intake is to torque spec I had replaced a few intake hoses and cleared the codes 2 days ago I haven't gotten a code yet but it still stumbles on cold start up it's not as bad as it has been but it causes my headlights to pulse like a strobe light and my interior lights while I'm driving but I have a new alternator and battery

 

Do you still have the OEM crappy Battery Terminal Connectors?


Are you using quality fuel every time (they call it Top Tier in many parts of the country)?

 

I do use top grade fuel but I have not replace the terminals. At this point I'll try anything

 

I replaced 2 intake hoses and terminals and cleared the codes I drove less than a 100 miles light came back on with p1174 twice and p0171

 

How many miles do you have on the vehicle?

What air filter are you using?

Do you have a scanner that will allow you to see what is happening in warm up when the PCM switches from open loop to closed.
Even though you replaced O2 sensors, you can get a bad one (anything electronic) right out of the box.

 

I do not have a scanner the reason I replace the O2 sensors is because I had low voltage Bank 1 oxygen sensor everything I replaced I had a code for this H3 has been a nightmare I didn't do the extemporaneous work because of a lean code and I don't use cheap parts I use original equipment but I have replaced so many parts I'm stumped I did a fuel pressure test I turn the key over to start I have 60 lb then I did leak down test I lost 8 lb in 10 minutes when I did the idle test a bounce back and forth erratically between 52 and 60 when I rev up the gas it was perfect holding strong without fluctuation with eight pounds in 10 minutes seems like I have a bad regulator or check valve

 

Also I forgot to answer your question about the air filter it is Factory no aftermarket on this vehicle at all