Safe to drive while running lean?

I have another thread here https://www.tacomaworld.com/threads/unsolvable-p0171-system-too-lean-code.427824/on my current woes with a P0171 code that won't go away, despite Toyota having looked at my truck for 3 days.

I'm scheduled to take it back in to the dealership I bought it from since I'm still under their full 30 day warranty protection, but I can't get it there for another 8 days (it's 3 hours away and I need my truck to get to/from work).

So my question is, will I be okay to commute in my truck in the meantime? My '04 is supercharged, so I will obviously be doing my best to keep it out of boost. But I just read online that some guy's Hummer (H2) had a P0171 code and the engine blew up on him while he was on the highway. Probably a rare occurrence (plus it was an H2), but nonetheless now I'm worried that I'm a ticking time bomb. If so I'll take the hit on my work hours and go to the original dealership asap...thoughts, experiences?

For what it's worth, my truck runs normally. If anything, I've felt a slight loss of power since the code popped up but she idles just fine and starts up with no issues.

 

I remember on the previous someone said running lean it's not your friend.

 

depends what codes/trim readings were you getting?

 

It was a code P0171, 'System Too Lean, Bank 1"...that's exactly what the reader said. Dealer has so far replaced my MAF sensor, o2 sensor, spark plugs and wires to no avail. Long story short, that same dealership had my truck for 3 days and apparently couldn't figure it out and told me they weren't willing to work on it anymore, that I needed to take it back to the Toyota dealership I bought it from last month and have them work on it (which seems odd for a dealer to refuse work, you'd think they would know how to address a lean fuel system).

At any rate, I'm taking the day off work on Monday to deal with this once and for all (hopefully) by taking my truck to the original dealership and getting them to work on it like they promised to. I seriously suspect a vacuum leak, but we'll see.

 

Running lean burns valves. (At least it used to...)

You might want to check out Enterprise Toyota in Canoga Park. It's the only place I will take my Tacoma to. The owner's name is Jerry, and he's helped me out several times. Unfortunately I moved to Colorado 21 years ago so now I have to do all my own work on the truck. I did see him in 2014 for a smaller problem though. Same Jerry, 20 years older, same high quality workmanship.

 

I wouldn't risk it. Running lean can and will destroy vital engine parts in quick order...

 

Thanks guys. I'm keeping her parked all day today. Tomorrow, have to drive several miles for a job, then Monday morning I'm going straight down to SD to get her worked on. Unfortunately, that's a 120 mile trip one way...

 

well the thing is. the codes are reading too lean, but that usually means that the computer is just compensating that much in order to achieve the proper fuel ratio. get a cheap scanner like an ELM327 and the torque app, 8 bucks tops, just gotta wait for it to get shipped. set it up for fuel trim and o2 sensor readings. if your O2S1Eq is 1, regardless of what your STFT or LTFT says, your truck is running fine and is drivable. the fuel trims being off means that, when your O2S1Eq is 1, your cpu is properly adding/removing fuel to keep stoichiometry, 14.7:1 air to fuel ratio.

 

Interesting, thank you!

The code actually went away this morning, which gives me some hope that it's not as dire of an issue as I was thinking it was. I still feel a slight power loss and definitely have worse than average MPG, so I'm still taking it in on Monday. I still hear what I believe to be a leak coming from the throttle body, maybe a bad TB valve gasket.

I'll definitely look into that scanner though, thanks for the info!

 

oh, an air leak? if you suspect anything at all. you can test it very easily! get a regular spray bottle with water and spray around any crack that could cause in intake leak. you will hear a sucking sound much like drinking from an empty cup with a straw when you hit an intake leak.

 

Yeah I suspect a leak not only bc of the sound, but because Toyota already replaced my MAF, o2 sensor and plugs to no avail.

Someone earlier recommended the spray bottle with water and soap but then someone else then said that could be bad for the motor If it breathes it in, at any rate I'm seeing a TRD specialist tomorrow morning in San Diego under warranty, so I'll let them tinker with it. Thanks for the help though! I'll let you know how it turns out.

 

What do you think goes through engines when it rains heavily? plenty of moisture. much less than if you were to spray a little around the engine looking for intake leaks. just dont do it with soap. i think the soap is to find compression/exhaust leaks like around the head gasket, injectors, or in the exhaust.

 

Yeah you're right, makes sense the soap idea is to detect air leaking out, not air getting pulled in. At any rate, my CEL actually disappeared this morning lol. After all this headache it just goes away. Still taking it in tomorrow in case it comes back, which it likely will if I don't find out and fix the underlying issue.

 

Yeah I'd keep it parked, running too lean means too much heat. This is caused when the engine gets too much air. Not sure about trucks, but I've seen pistons in motorcycles and quads melt themselves to the cylinder walls because the engine was running too lean. Definitely not good! Best not to risk it until you get it fixed, that's for sure.

 

I'm no supercharger guru and even less of a "guru" when it comes to all these new vehicles and engines but one thing I DO know. If you have a supercharged engine or any engine for that matter and you know it is running lean you better park it until you find out "why" it is running lean. Lean equals heat and too much heat will ruin an engine or at least take some serious miles off of it's longevity. I hope you're running a synthetic oil. It's good insurance for too much heat.

 

Thanks for the info! I actually finally got the issue resolved, there was a port on the back of my supercharger that had become uncapped and created a vacuum leak that made it run lean at idle. Took the service techs nearly a week to figure it out, but all seems to be well now.

Since then, I've actually read a few old threads on here about other members with superchargers experiencing the same thing, it's somewhat common for that port to become uncapped especially if you off road a lot. Now that I know I'll know to keep an eye on it.