My wife took the Toyota 4Runner out for an errand, and it started running like crap just down the street- rough idle, down on power, CEL on and "VSC TRAC" "VSC OFF" also came on. This was abrupt- it was running like a top just a week ago, but them temperatures have been weird the past week: from the 70s down to the 20s, back and forth.
I limped it back home, and got the following codes using an OBDII reader:
P0300 - Random Misfire
P0171 - System too Lean bank 1
P0175 - System too rich bank 2
The "VSC TRAC" "VSC OFF" lamps went off when I turned it off and restarted it.
Given that it was so sudden, I am thinking a connector or sensor is disconnected or something just failed. The plan is to clean the MAF and check the plugs/wires/coils and lastly, the 02 sensors and all of their connections on the wiring harness.
Any other thoughts?
Is a T4R some sort of Toyota? They shut down the stability control whenever the engine throws a code.
Ah. Toyota 4 Runner, perhaps...
Anyway, when you have one bank lean and the other rich, you either have a big vacuum leak into one bank, or a big fuel leak into the other, or one dead O2 sensor. Does the exhaust smell pig rich? Change the sensor that says lean. Does the thing seem terribly lean? Change the one that says rich. If you have scan data, look at the rear sensors- One may not match what the front one is saying.
Look for something that only affects one bank.
Yes, Toyota 4Runner, sorry. The exhaust smelled a bit rich.
I'll check for Vac leaks, thanks for the reminder. There aren't many vac lines, so it should be easy. It's probably time to replace them, anyhow.
As for water in the fuel, we did just fill it up last week. We drove 15 miles or so after the fueling and didn't drive it again until today.
Unplug the O2 sensor on the side that says lean, clear the codes and see how it runs. If it runs ok then, take it for a bit of a drive and make sure it stays ok. Then plug the sensor back in and see if it gets worse again.
Hmmm foloowing along. Mine runs fine but the VSC and TRAC lights will sometimes flash alternating if its hot out. A key cycle clears it up. No codes though.
Were they just on, or flashing?
My wife's '10 Sienna did the same thing recently. It threw a code for the VVC not advancing one exhaust cam on the V6, then threw the VSC codes. Btw, changing the oil solved the sticking solenoid on the VVC.
Scion xb's throw all 3 for cam or crank timing sensors and also for charcoal canisters. Toyota seems to think one light isn't enough.
My 99 threw a similar code and acted like that when an injector died. I know you've got a different engine but it can't hurt to check.
EDIT: I got a too lean code, my bad. Maybe you've got a wonky spark plug, lead, and/or coil. Check that by swapping coils around and see if the problem moves.
Dunno about the other codes, but the VSC will turn off if the voltage drops. Check alternator voltage at idle with heater, lights, etc. on.
Ignore the stability control lights on Toyotas. They shut it off immediately with any engine codes. Fix engine, clwar codes, proceed.
In reply to Brett_Murphy:
Random misfire and lean bank: look for air leaks between MAF and throttle body. Especially if it gets oil changes at a quickly place that tries to sell you an air filter every time.
so unplugging the O2 sensor.. what does that do? I need to replace the exhaust system on my rover due to some shenanigans from a previous owner. They replaced the passengerside cat with an aftermarket unit and spaced the O2 sensor to fool it. The sensor eventually clogged, but due to corrosion on the spacer, I can't remove it.
I am going to replace the whole system once the weather warms up some, but until then, my truck is running pig rich because it thinks that bank is running lean. Would unplugging the sensor help?
If you unplug the sensor and clear the adaptive memory, it will run off the base map. If the sensor is bad, and forcing the system rich or lean, getting it to run open loop will straighten it out. Alternatively, if its NOT the sensor that is causing the problem, it will run worse. Poor mans diagnostic tool.
In reply to Dr. Hess:
I had this issue when a battery went abruptly on me. Christmas tree lights and barely running. Toyota sure likes to turn on many lights at once.
Glad this thread came up. My wife's Solara just popped a bunch of lights.
Brett_Murphy wrote:
As for water in the fuel, we did just fill it up last week. We drove 15 miles or so after the fueling and didn't drive it again until today.
In my experience, you know within about 300 yards that something's wrong with bad fuel. I would cross that off the list of possibilities.
Popped the plugs out at lunch time and the electrode is worn to a point. I know platinum plugs have a taper at the electrode, but these look sharp. Going to replace those first. Not sure if I want to do the coils at the same time or not.
Also, the MAF was a tiny bit dirty. I cleaned that off, too.
I am loving how much room there is in this engine bay, though.
Put in the new plugs. It started right up and smoothed everything out enough that it seems like one cylinder isn't firing. The smell of gasoline was rich in the air while it was running, and I have a nice shimmy/wobble going on from the engine. Now I just have to figure out which cylinder isn't right and why it isn't right.
Looks like I have to get a coil on plug tester.
You could disconnect one coil pack at a time and see if it changes anything. Just like a spark plug.
Excuse my ignorance here, but wouldn't disconnecting coils make it run worse?
In reply to Brett_Murphy:
Yes, but if one is bad (really Needs to be failed) it won't run worse when you pull that one.
Yeah, when you pull the plug on the bad one, nothing changes. Pull the plug on a good one, it runs even worse.
