Mechanic question for my 2000 4runner

[Wasatch Rebel]

If you know anything about check engine lights, especially on 4runners, here's a question for you. A few weeks ago my check engine light came on. I didn't have time to deal with it right then, so I had a check run at Autozone, found out it could be about six different things. I thought about it for a day or two and then then one day I went out to start the 4runner and the light wasn't on. It stayed off for a month or so until just a couple of days ago when I was coming home from Yosemite. This time I replaced the gas cap, but the light stayed on after that. A few hours later after stopping, I started it back up and the light was off. Then a few more hours after that, after refueling and starting it up again, the light was once again on.

Any ideas as to why this is happening would be appreciated.

 

[chans]

What code does it show? P0440?

 

[Spork]

Code would help...

I have a Tacoma with a similar issue, Light will come on at random and then turn off. I just ignore it unless it's about time to get it inspected.

 

[KWight]

My 1995 T100 Check Engine light has come on twice over the past three years. Both times it was when I was towing up some steep hills. It stayed on after that and I had to reset the computer to get it to shut off. It did not come on after either time until the same driving condition was repeated. I would suggest you try to reset it and see if it goes away.

Kevin

 

[Wasatch Rebel]

I'm going to have to get the code I guess. The time before, a month or so ago, I think I saved the code from that, but it may be different this time. Anyway, I was reading in the user manual and it says something about the light will stay on for a few startings. So, it may have been the gas cap and it just hasn't reset itself yet. Of course, that doesn't explain why it went off and came back on again.

 

[193kyle]

Pretty common for an 02 sensor to do that

 

[Silly Willy]

it could be the cap, lots of cars have the light come on if the cap doesn't (click) 3 or so times. Or like Kyle said its common for an o2 sensor as well.

Best bet is get the code and go from there.

 

[lewis]

My bro in law has the same year 4 runner and the check engine light comes on all the time. He cleans of the mass air flow sensor and then it goes off for a few months.

 

[Wasatch Rebel]

Thanks for the help. I think all three of those things showed up as possibilities on the code when I ran it a month ago--02, Mass Air Flow Sensor, Gas Cap. And there were 3 other things as well. If I remember right the code said the air/fuel mixture was too lean. Or was that too rich? I guess I'd better get that code again.

 

[NOTATOY]

I have had several Tacos and they love to go through 02 sensors, and cats occasionally

 

[SLC97SR5]

I have had several Tacos and they love to go through 02 sensors, and cats occasionally

Not sure what you guys are using for 02 sensors but the Bosch sensors the parts guys push are garbage, slow reacting and will throw codes.

Use the Denso's and I'd be suprised if you foul any more cats or throw codes.

 

[Wasatch Rebel]

I'm going to bump this up because I finally made it to Autozone for the code. The code is P0171, which shows my air/fuel mix to be too lean, and these are the possible causes, according to the list I got from Autozone:

1) Low fuel pressure
2) Faulty MAF/VAF sensor
3) Cylinder misfire condition
4) Faulty HO2S/AF sensor
5) Large vacuum leak

So if this helps anyone with the diagnosis, let me know. And if you can tell me how to clean the MAF sensor, I'd like to know that as well.

 

[chans]

Here is the FSM to help fix the problem.
http://www.ncttora.com/fsm/2003/Repair_Manual/03tacoma/di/eg5vzfe/cip01710.pdf

They have a special spray to clean sensors that you need to use on the MAF. I have a complete FSM for 1999 Tacoma and 4Runners you can look at also. I would clean the MAF then check all the vaccum lines then replace the PCV and if you still have the code take it to the dealer if you don't have a hand held tester or ohmmeter.

 

[Wasatch Rebel]

Thanks. And thanks as well to all who've responded on this thread. You're a big help.

 

[lewis]

So did you get it figured out?

 

[Wasatch Rebel]

So did you get it figured out?

I think. Maybe. I got some MAF cleaner, but I was unable to get the upper screw out. So I unhooked the electrical connection just did what I could to spray it where it was visible, and up inside the air tube. I tried unplugging the EFI fuse for the duration of the work, then put everything back together, plugged the fuse back in and turned on the Yota. The check engine light was still on, so I took off the negative battery cable for several minutes to clear the computer. Once I reattached the cable, the check engine light was off and has remained so, even though I spent all day today four-wheeling on the roads up Manti Canyon. I'm hoping it's fixed for now, but I want to get a screw remover and get that screw out and do a better cleaning job. That MAF cleaner sounds pretty toxic and I don't want to mess around with it too much. What kind of a respirator should I use for this highly carcinogenic stuff?

Anyway I want to do some other stuff, not the least of which is get rid of my K&N air cleaner once I can get the bucks together to get an original cleaner, as I found dirt way up at the intake on the engine.

 

[radjeeper]

I had a 2000 Taco that had the check engine light from hell. After trying everthing to get it to stay off (changed a coil, cleaned injectors, changed fuel filter, cleaned MAF sensor a few times, changed the O2 sensor, reset the computer several times. Finally one of my techs fiqured it out. He pulled the codes, got on the web and researched the problem. Of course there were those that said it was the cat. However, experts told me that 9 times out of 10 it is not the cat. The research pointed to the idle control motor. Rex pulled it and found that it was filled with black carbon deposits. We replaced it, not cheap, reset the computer and the check engine light never came back on. You don't want to know how much that whole stupid deal cost me. I even took it to a Toyota specialist who's bright idea it was to clean the injectors and change the fuel filter. They were just guessing. Praises to Rex.

 

[Wasatch Rebel]

That's definitely good to know. I will keep that in mind should I end up with the same engine light from hell problem.

 

[SLC97SR5]

The research pointed to the idle control motor. Rex pulled it and found that it was filled with black carbon deposits. We replaced it, not cheap, reset the computer and the check engine light never came back on. Praises to Rex.

AKA on Toys, IAC or Idle Air Control, this sensor sits under the "throat" of the intake right where the throttle body meets the intake manifold and is subject to all the crap ingested from the PCV. You can remove and clean this sensor, it's usually all it needs. The MAF cleaner works great for this.

RadJeeper--Nice find