Hello! First time posting on this website..

So I have a 2013 Buick Lacrosse with the 3.6 LFX engine and 92,5xx miles. I've been suffering a pretty steady misfire so I had taken it to a shop and they diagnosed it as a bad fuel injector. The closer I get to the repair the more I begin to question whether or not it'* an injector or potentially a bad coil.. Hopefully this isn't information overload!

Anyway, that'* where I'd like a second opinion given the scenario.

It'* currently throwing these codes:
P0157 - Oxygen sensor Circuit Low Voltage Bank 2 Sensor 2
P0171 - Fuel Trim System Lean Bank 1
P0174 - Fuel Trim System Lean Bank 2
P0300 - Random Misfire
P0302 - Cyl 2 Misfire
P0442 - Evap Leak
P0496 - Evap Flow During Non Purge Condition

The shop believes the culprit is the Cyl 2 injector and the purge valve.

I went to school for automotive, I have a lift, many tools, and I'm more than capable of performing such a repair. I just want to make sure I'm not going to replace parts blind with my fingers crossed that it'* the right part. I have seen too many incorrect diagnoses to take this at face value.

So my question for you guys - have you ever had an injector go out? How many miles? I know these are direct injectors so they are subject to harsher conditions but the more I research this it sounds like it'* more likely to be a bad coil pack.. I wish the coil packs weren't under the intake or I'd just swap the cyl 2 coil pack around to see if the misfire code jumps from one cylinder to another but I have a hard time buying a new gasket each time I take the intake off. In my estimation I feel like I should need to replace the fuel pressure sensor, spark plugs, and coil pack(*) and clean the intake valves. Being the condition is throwing a lean code on both banks I have a hard time believing it'* a single injector causing all the problems, dirty intake valves sound more likely. I understand these have a standard fuel pump and a high pressure secondary fuel pump for the higher pressure requirement of the direct injection system. Is there a way to check and see if the high pressure pump is working okay?

Thank you for your time!

I would look at it with a scope.

Welcome!

How did they diagnose this?

Is it a stuck-open injector or stuck closed or low flow?

P0157 - Oxygen sensor Circuit Low Voltage Bank 2 Sensor 2 >>>>> CathedralCub believes this is not related
P0171 - Fuel Trim System Lean Bank 1 >>>>> CathedralCub wonders why both banks are running lean
P0174 - Fuel Trim System Lean Bank 2 >>>>> CathedralCub wonders why both banks are running lean
P0300 - Random Misfire >>>>> CathedralCub believes this is caused by the lean condition
P0302 - Cyl 2 Misfire >>>>> CathedralCub believes this is the one that is misfiring the most in an engine that is showing random misfires caused by the lean condition
P0442 - Evap Leak >>>>> CathedralCub believes this is related to the lean condition
P0496 - Evap Flow During Non Purge Condition >>>>> CathedralCub believes this is related to the lean condition

Based on these codes, my advice: Replace the purge valve. It is easy. Then reset everything and see what codes pop up.

I agree that the purge valve should be replaced.

I've been in contact with three of this engine family for years. They are an LY7, LLT, and LFX . I've never had an issue with any part of the fuel systems on these. Knock on wood. I also haven't heard of more than a couple of injector replacements on this engine family in the world. I'm not saying it doesn't happen, I just have seldom heard of it across bazillions of units. I've heard of bad knock sensors in 5.3 V-8s. I've heard of intake manifold issues on the older LT1 V-8s in the 1990s. I've heard of the plastic intake manifold failing and hydro-locking GM 3800s. I've heard of oil consumption issues on the Ecotec 4-bangers. I've heard of the timing chain issues on early LY7s. Etc. Etc. I've almost never heard of fuel system issues on the GM 3.6 high-feature V-6.

Between them they have over 400,000 miles accumulated.

For what it'* worth, I've never had a coil issue across any of the above-mentioned vehicles.

Two of the above-mentioned engines have had spark plugs done after they turned 100,000 miles. None of this other stuff has been done nor found necessary.

Not to me. I can't imagine a scenario where at least six intake valves become dirty enough to cause this at nearly the same time, but don't cause major compression issues and the car keeps running. Your car would be the first ever that I've heard of with any significant valve problem in a GM 3.6 high-value engine.

Yes, but I think you are way far away from needing to do this. Again, not often I've ever heard of a HPFP going out on one of these.

I'll replace the purge valve today. Thank you so much CathedralCub! I would gladly give you money for your wisdom.

Why not just test the valve. If it opens and closes OK and holds vacuum it'* good.

LOL my advice isn't good until it fixes something . . . until then it'* just some advice from some weirdo on the Internet.

I'm sorry to have wasted your guy'* brainpower in this! I took the codes the shop wrote down at face value.. When I ran the codes myself they pertained to a misfire on cyl 2 and an open circuit on cyl 2 injector. I took out the injectors and sure enough there was no continuity between the two terminals on the cyl 2 injector. All other injectors had right around 2Ω including the brand new OE AC Delco one I had purchased. So now I'm ordering the injector sealer tool and picking up the Teflon seals for the 5 other injectors through the local dealership before it all goes back together.

Should I be replacing the fuel pressure sensor on the high pressure fuel rail as well?

Your advise is thorough enough for me to be grateful for it!

I'm not sure if the sensor is a problem or last a lifetime but the price is such that I would likely spend the time and money and consider it PM.

Agree, while you have it apart you may as well.