JohnVickiB

I am having a hard time diagnosing an intermittent P0171 code. I have posted my engine codes from OBDII at idle with A/C on and driving at about 2700 RPM. I am not sure if I have a vacuum leak or a valve is not working correctly. The P0171 code is an intermittent problem, sometime my long fuel trim is at 19.5 and sometimes it is over 30 (when I get the error code) (see pictures). What it the normal reading in the first place? Is 19.5 at idle good or should it be lower? I have (all Denso) changed front O2 and MAF sensors, fuel injectors, plugs and wires. Can't find any vacuum leaks but haven't done a smoke test yet. It does run good still and MPG on Hwy is about 17 to 18 MPG. Does anyone have any ideas? Also, I have 217.000 miles and still love my 4Runner.

75w90mantraN

Alt test for vac leaks is using spray bottle with soap/water on suspected areas and looking for bubbles.

Something is making your runner run lean....or it can be electrical in nature and giving you false readings...

If you haven't changed fuel filter, I'd throw a new one in there. Clogged would contribute to a lean fuel mix.

Can always erase the code and see if it comes back, if it takes too many miles to clear on its own. Does your scan tool have a snapshot of the data when the code first appeared?

75w90mantraN

http://www.agcoauto.com/content/news/p2_articleid/197

PCV valve also worth checking/replacing. Unless it's been replaced already.

JohnVickiB

I did a spray test on my charcoal canister and it was cracked. I got JB Weld and sealed it following steps from a youtube video , no further problem. I am making a smoke machine from another youtube video probably this weekend.
I wondered about the electrical and if the P0171 is intermittent, wouldn't it be constant after warming up? I am going to check the electric connection to my O2 sensor after I do the smoke test if I don't find anything.
I have changed the fuel filter and PCV valve also. Scan tool is cheap and doesn't have a snapshot capability.

75w90mantraN

How's the idling? Steady or all over the place? I see with a/c, the 832 rpm. When does the code come on? Seems like you've covered many of the common suspects. Can't say about intermittent codes and electrical associations but neither should it be ruled out. If you found a leak on one area, there's prob other places too, so I wonder what you end up finding with that smoke test.

75w90mantraN

Exhausts leaks before a/f sensor can also set that lean code. If there is, you can seal that with stuff sold at the local auto parts. Exhaust gaskets are difficult to inspect, so I'd prob get a mirror to help see behind things.

JohnVickiB

Idle is great and smooth, usually about 700 RPM with A/C off. Code comes on after the thermostat opens, about 5 minutes after I start it. I can clear it and it may or may not come on for a while, all of my trips are usually about 5 to 7 miles at a time which is about 15 to 20 minutes 4 times a day. I drove 220 total miles to see my kids a couple of weeks ago and it only gave the P0171 code when I first got going and again when I was almost back home.
I have started on my smoke tester and it should be ready when I have time this weekend. I will also check the exhaust too.
This 4Runner is in such good shape (knock on wood) I want to eliminate this problem and keep it for several more years. I will post the results of my tests this weekend.

JohnVickiB

I did a smoke test yesterday, then tightened a few hoses and fittings. So far no P0171. I torqued my fuel injector rail down when I changed the injectors but I had a little smoke coming from injector 1. I didn't know what else to do so I wiggled it some and tried to re-seat it. I think that may have been a problem, if I can drive a week with no code I will be happy.

75w90mantraN

Looks like you had a good week. For me its been like wack-a-mole -- fix one problem and another one comes up. Hopefully these engines do go much longer.

JohnVickiB

Hope you get it all fixed up soon. I have my 4Runner running really good, had it repainted a year ago, I really like it. UNFORTUNATELY someone hit me yesterday. They thought they were on a 2 way street when it was actually one way and tried to turn left onto a street from the right lane. They only messed up my right rear bumper and broke my rear mud flap off. They have insurance so things will be okay I hope. BUT I still love my 4Runner.
One thing I did this year that I am very impressed with: I had a minor head gasket leak for a year. Only smoked once in a while but it started rough every morning but ran good after it warmed up. Used just a little anti-freeze. It was getting antifreeze in #3 cylinder. I heard about BlueDevil Head Gasket Sealer and finally ordered some for a test. I pulled #3 spark plug. removed thermostat, and let it run for an hour (sounded horrible so I mowed my lawn to drown out noise). I put new thermostat in and reinstalled plug, no more problems with that.

75w90mantraN

I've wondered if that stuff really does work. I tried unsuccessfully on a 92 dodge ram pickup but the pinhole in the block was too big for just 1 bottle (plus it was a bigger engine and it recommended 2 , but I ran out of time for the 2nd purchase). Coolant/water would literally pour out immediately after being poured in through the rad.

My troubles on my runner are mainly the chassis. I messed up my door foolishly thinking I can dump out some snack wrap quickly while in neutral without the parking brake. The 4runner coasted backwards a little before I can get back in time and the door got pushed forward while it was open. Stupid I know. It will close but I can tell it is somewhat pulled out of position. Not long ago, I tried to pull back my side mirrors to park close to a friend's house and it was so seized up inside it couldn't turn anymore and snapped off. And a few months ago, the rearview mirror decided it was time to let loose and fell out of its holding slot as I went over a bump. I feel like cosmetically this runner is falling apart literally. Both issues I hoped I resolved with some JB weld bond. That was last weekend.

There are a few other mild mechanical setbacks (flywheel/clutch worn, valve cover leak), but other than that great as ever. Just put some Bilstein shocks to replace broken originals and oh what a relief. When I get some time I'll happily work on them and post pics in another post.

Glad no injuries for you...and some people think its stupid to look both ways before crossing a one way street. Your case is exactly why we still need to be on the look out.

You're in good hands...in a 4runner.

JohnVickiB

Man, I hope your JB Weld works out good, I love that stuff.