P0171 too lean bank one

Hadn't got that far into looking into it past the MAF cleaning. Gonna get under, in, and around it this weekend and see what I can find.

 

Are you getting any other codes? I was getting p0171 for awhile and another code (p0136) which indicated my bank one sensor two was going bad. Replaced it and problem solved.

 

No other codes or pending codes. Gonna clean all connections later

 

P0171 popped up again (no other codes). I had a feeling that it was my brake booster due to a sudden stop that I needed to make. It felt very different, and now there's a weird hissing sound when I am on my brakes. So I had the shop check it out, and that's what it was.
Any recommendations on a brand and/or store for a brake booster? Toyota is way too expensive, and the shop wants around $400 for the booster & labor.

 

I have had good luck with the brand from O'Reilly auto parts. $150 ish

 

https://www.yourmechanic.com/articl...e-code-system-too-lean-bank-1-by-andrew-quinn

 

I had that code after cleaning my throttle body and MAF sensor. I took off the throttle body though. Try removing it and putting back on, may be a loose connection? Will give you good room to inspect hoses anyway.

 

So about 2 weeks ago or so my long fuel trims went through the roof and when cruising they are
at 25-30. Typically they are at +-5,

I took it in to the dealership and they did a smoke test, came back with no leaks,
Then did a fuel pressure test and was at 46, normal is 44-48,

Put in a new OEM DEALERSHIP MAF and still didn’t fix the issue.

Now the AFR is climbing to 13.5 -14 under full boost when its normally at 11.5 under fulll boost.

I can now hear the truck ping under load too.

Today the code p0171 popped up.

Can this be from a weak fuel pump?

Don’t know what direction to go?

I have an EGR system but the trim codes came out of nowhere to positive 20-25
and there has been NO engine work done on the truck since the timing belt 6 months ago.

Where do I go from here

 

Maybe the fuel pump like you say...might be performing normally under normal conditions but when you floor it and all 10+ pounds of boost kick in, maybe it's struggling. Fuel trim numbers are normal when not in boost or still off?

If things are only whacky when under boost then I would suspect the fuel pump as well, a lot of people are usually surprised to hear you're still running the stock output fuel pump, so maybe it's finally just getting too tired for the demand of the supercharger?

 

That’s what I’m thinking the fuel pump is getting tired, the fuel trims are still high even when the methonal is spraying too.

Just wanted to get feedback if it’s something else before I deal with removing the bed for a new fuel pump.
1st fuel pump was replaced at 300k, I’m at 605k now

Fuel trims are all out of wack all the time now except idle. At idle short and long are at zero

 

If you do another pump are you going to get a higher flow one or stick with OEM?

If higher flow I'd recommend the Aeromotive (sp?) brand high flow pump...the Walboro one I have whines like crazy when it gets hot or is hot outside. Has done so since it was new 2.5 years ago

 

I would start with a pressure and flow test... it ALL starts with the correct amount of fuel being delivered. Check the vacuum line at the fuel pressure regulator too for vacuum and see if the regulator has fuel on the vacuum side and if it holds vacuum.

 

When i had this code it was a split hose on top of the manifold. Just a tiny split was enough to throw it.

 

These trucks are extremely sensitive to vacuum leaks it seems...which is why this is probably the most commonly talked about code on here esp on the 1st gen forum with how old our hoses and seals are by now

 

I’ve had plenty good luck with the stock fuel pump, tried and tested lasting 300k miles.

I had the smoke test done at the dealer and replace all my vacuum lines under the hood, so no leaks found.

Pulled the trigger 4 hours ago and installed a new DENSO pump and filter.

Reset the ECU and took a quick drive and the long term fuels trim are no lomger +25.
They are at -4 now.

Looks like the DENSO fuel pump runs about 300k,
1st one failed at 300k and now my 2nd one failing at 605k
with P0171 code (lean code, MAF code)

Will see how it goes after the ECU is relearn.

I unbolted the bed and tilted it a bit.
Just be careful with the bed rear lower quarter panels as they have
NO structural support and can buckle under the weight of the bed.
You need to support the bed from the center section to carry the bed weight.
The front quarter sections have body supports.

 

Nice work hombre. Those Denso fuel pumps have been great for me

 

Seems you can’t go wrong with denso brand on these trucks.

 

Hear me out. You are spraying methanol for your extra fuel in boost, right? You're probably spraying in closed loop too- because supercharger. So you're adding extra fuel, the ECU is going to pull fuel from LTFT to make it stoich in closed loop. Over a long time, your ECU has screwed itself up trying to fix your methanol spraying. You've probably just reach some sort of imbalance from extra fuel then fuel pull, rinse and repeat. Unplug your ECU, reset your ECU, then I'll bet it goes back to normal. I was using 100% methanol for my extra fuel a few years ago and I'd have to reset my ECU every few months because of things like this. New fuel pump probably still isn't a bad idea.

 

Got what your saying, but I have 60k miles on the methonal and the engine was pinging even out of boost which it normally doesn’t do.
I did reset the ECU twice no different

This is the 1st time I’ve had these issues so crossing my fingers the fuel pump was my issue.

 

OK got ya, I didn't read the entire thing.