2004 Prerunner 2.7L (CEL Code p0171 p0110)

That relay looking thing is supposed to be there. Toyota calls is a noise filter or something similar.

 

That's some mess of codes. Do you have access to the FSM? The diagnostics for the 171 are quite involved. And you are still getting the 100 - mass or volume air flow circuit. 110 - Intake Air Temp Circuit Malfunction. Then all the misfire errors. There is a lot to check.

 

If it wants to die when you move the intake around, that means something is wrong in that area. What does this intake look like? When you move it around you could be opening a crack or creating a larger vacuum leak. You could also have a wiring short going to the MAF which could be arcing when you move it around.

 

Do you think that setup is good? Or could this be a problem? Is this what CAI have to do to work?

Yea, it's getting me frustrated that I have so many codes. The only one that comes up consistently is the p0171 code. The others seem to be read and go away and then come up again. The mass/volume circuit is the same from the MAF sensor isn't it?

I will take a picture of the intake later if I can. It really looks like it was made from universal kit but never gave me problems. When I changed the spark plugs there is a possibility that I moved it since I did remove it to take the plug out.

Let's just say it was the wiring(for example it shorted out or melted or something in that nature) would I have to replace the whole harness?? :O That seems scary to me. There is no way that I think I would be able to do that.

 

That is stock, mine is exactly the same. That little box is a noise filter to reduce engine noise on the electrical line for the MAF

The wiring harness is most likely a large harness that has almost every sensor and component on it, at least on that side of the engine. The cost for that would be astronomical from Toyota. If it is a short, you will have to find the short and replace that section of wire. Unfortunately, intermittent wiring problems are some of the hardest things to diagnose.

What does the electrical connector for the MAF look like? Look on the harness side and on the MAF side. If there is corrosion then you need to clean it.

 

When I removed it t clean the MAF I did not see any rust/corrosion on the connections. I did see dirt as the pictures show but the connections inside themselves did not look bad at all. I do get a smell of something that smells like fuel and I think this is from whatever the problem is not reading the air maybe and therefore not burning the fuel completely.

I just hope that at least I can get it running well enough until I finish school in a few months.

 

FSM for the 300s says to diagnose any other DTCs first.

HINT:
If any other code besides DTC (P0300, P0301, P0302, P0303 or P0304) output, perform the throubleshoot on that DTC.

So that takes you back to 100, 110, 171.

 

Update:

Alright so my dad made the trip up here for me last night and we started to look at the truck this morning. We started with what we changed first. We took the plugs out and these suckers were black! Part I guess was the anti-seize they recommended but some for sure was from something else(exhaust).They were worse then the ones that we pulled out. I checked the part from Oreilly's to see if maybe they messed up the part when they gave it to me but no, the plug they gave me were the ones that it needed. So when I pulled them out I compared to what I had in there.

The only difference that I could see were that the ones I bought were "higher" quality and the ones I had before had a larger head(?) I'm not sure what it is called specifically but you will see in the pictures. The truck is now recovering from all that black soot whatever you want to call it but is running 100 times better. I will keep posted to see if the light comes back on.

Oh and I forgot to mention that the black plug was worse. This was after my dad brushed some of the black stuff off to see if maybe there was something cracked or broken or something like this.

 

Hope you got it.

I put Denso plugs in mine. They were the recommended brand. It ran the same before and after, so I probably didn't need them at the time.

 

With all of the misfire codes you were getting, it makes me think it was the wiring. Just pulling the plugs and reconnecting the wires could have fixed it. Either way, glad you got it running right! They plugs are black because it was running rich, meaning too much fuel getting dumped into the cylinder.

 

I used these because the dudes there said "go with the better ones" so I took the "best" they had. Hopefully I go back and either get my money back or get exchanged for something else.

Crossing my fingers that this is completely it. I hope that the smell I was getting was the fuel that was not being combusted properly. I was already thinking the worst in all the wiring. I will be waiting for the light to come on and see what I get from it. My dad did say he saw some smoke(leak) and told me to keep an eye on it to see if indeed there was a small leak. But at the moment I am glad that it is at least not limping anymore.

 

Alright guys so I still have the light for the lean condition and I do still smell some sort of fuel mixture. How can I effectively and thoroughly do some sort of test to crack down that leak? Or well at least I think there is a leak. I obviously do not have a smoke machine laying around so that is out. Any ideas? Recommendation? Price on what this might cost to do at a shop?

(I might just have to use this as an excuse to get my truck in the shop to do the 4x4 conversion :O haha it's been a long time waiting.)

 

What code(s) is showing?

 

P0171 It's the same consistent code that I have been getting. The hesitation for the most part is gone, I just get a small fluctuating RPM and I can smell something that smells like fuel.

 

P0171 is system too lean right? You smell fuel because the computer is sensing a lean condition and it is dumping fuel into the engine. This will make your spark plugs look black with soot from unburnt fuel. I bet your exhaust is very sooty as well.

How the code is set:
When air fuel ratio feedback is stable after engine
warming up, fuel trim is considerably in error on
LEAN side
(2 trip detection logic)

Possible causes of that code:
Gas leakage or exhaust system
Air induction system
Fuel pressure
Injector blockage
Heated oxygen sensor (bank 1 sensor 1)
Mass air flow meter
Engine coolant temp. sensor

Procedure (in order):
Check Air Induction System
Check Injector Injection
Check MAF and Engine Coolant Temp Sensor
Check Spark and Ignition
Check Fuel Pressure
Check gas leakage or Exhaust System
Check output voltage of oxygen sensor at idle

Go through these in order and you will find the problem

 

It just seems like it's starting to be one thing after another with this truck now. So about 2-3 months ago I changed the front cat with that I also put in a new o2 sensor there as well. I did the spark plugs(which ended up being worse), before I did the last long trip (same time as the spark plugs) I used an additive to help clean the injectors, I cleaned the MAF when I started getting the lights and I already washed/cleaned the CAI filter.

And yes the exhaust does have soot. If and when I do fix the problem is there anything I can do to "flush" or clean my exhaust system?

 

How many miles? I have a rough idle that developed only while in gear (park or neutral is fine) and I have been unable to correct it. You can see what I have tried here: https://www.tacomaworld.com/threads/2-7l-rough-idle-diagnosing.466233/

Has your valve clearance ever been checked or adjusted?

 

I believe its somewhere around 170k.

And no I have not had it checked.

 

UPDATE: Alright guys so it's been two months of just looking all over up and under the truck to see where this leak was coming from. Way back maybe 2 years ago I bought a gas cap that later had given me a code so I removed it and placed the original back. So since I had the new cap I really didn't use I tried and what do you know the P0171 code went away. But as seems to be the case now there was a P0135 code. Something about the heater circuit on the sensor(the sensor I had replaced not too long ago as well). Well I removed it and it was so full of soot! I already had the new one so I just swapped it but I guess since it was reading wrong there was a ton of fuel therefore clogging the sensor? The sensor looks almost new after I wiped it down but I just went with the new one. I hope this completely fixes my troubles. I took it for a ride and it seemed to be idling way smoother I'm just worried that it might get clogged again. So for now no CEL and I will see where we go from here