2004 Prerunner 2.7L (CEL Code p0171 p0110)

So this weekend I decided to do some traveling and visit my parents. I decided to spend some time with my dad working on the truck. We changed the spark plugs, oil change, changed an o2 sensor(since a few weekends before we had swapped out a catalytic converter) and I decided to clean the air intake filter on it as well. Fired her up and good as new, traveled back home and the next day CEL! fml

Got the truck scanned and gave me the following codes:

p0171: System Lean Bank 1?

p0110: Intake Air Temperature Sensor?

The symptoms that I am getting is that it is idling super low (maybe ~500s, ~700-800 with A/C, ~1000-1100 cold start). When driving it is super sluggish, it shakes and almost seems like it wants to die but it doesn't.

I am limited on tools and places to do any "work" on my truck but I will be trying to diagnose it myself. I already have gone back and checked to see if there is any vacuum leaks but I do not see any cracks or any hoses that may have detached. I believe that the MAF sensor is suspect since I did clean it (air filter) and oiled and possibly over oiled it when I put it back.

I will update on what I will be doing and if there is any advice out there I appreciate it. I have been reading from other forums. Just here to provide my experience with this problem and get help from others.

 

P0171 is common on 1st gens and is usually related to a vacuum leak somewhere. Happened to me and in most other threads on here, seems like that's what it ends up being. Check all your hoses and seals where they connect for cracks or loose connections.

It can also be a dirty MAF sensor, which is cheap and easy to clean yourself so I'd give that shot first (use MAF cleaner only, not carb or electrical cleaner).

Other possibilities are bad O2 or air/fuel sensors or maybe a leak in your exhaust. But those usually generate other codes.

 

Regarding the P0110, I read this online...

• Intake Air Temp sensors must operate within specific ranges to send correct signals for the ECU to coordinate with the throttle position sensor, Manifold Air Pressure sensor, and Mass Air Flow sensor to adjust correctly for proper engine operation.

...makes me wonder if maybe you have a bad Intake Air Temp sensor and it's throwing off your MAF sensor which, in turn, is throwing your P0171 code perhaps?

 

Hmm yes, thanks for the input. I will be checking that tonight when I get home. The easiest for me at this point it to remove the MAF clean it and test that. I was super stoked to have my truck running like a charm since having to replace the cat and sensors. It's frustrating to know how well it ran for 250 miles the day before and then wanting to stall the next morning.

 

did you say oil the MAF sensor?
are you supposed to do so? as for the p0171 code check if the o2sensor is properly tight. had the same issue once and it was the o2 sensor was loose.

 

Oops! What I meant to say was that I took off the air filter, cleaned it, oiled it and placed it back. In a way I guess I did "oil" the maf since I believe the excess oil on the filter might have been sucked in and clogged the MAF. The sensor should be good since I literally replaced it on Sunday and drove 200+ miles and nothing. I will take a look at it though any advice will be taken.

 

ok make sure you clean it with MAF cleaner.

 

You're using an oiled air filter? You should replace that with a dry one IMO, those oiled air filters are no good for MAF sensors. Could be part of the issue here

 

It's a K&N air intake filter. I don't do it often as I am not out on dirt roads often. I just took it out gave it a rinse with the cleaner, oiled it and the placed it back. I might have not let it air dry completely. Again this is why I am thinking it is the MAF sensor. So tonight I will clean the MAF and retry it.

 

I had one of those oiled K&N's in my old '99 Prerunner and it toasted my MAF sensor not too long after I put it in my truck; they're not usually recommended on here. I really like the aFe Pro Dry filter, it's not oiled and it's washable so you can reuse it like the K&Ns.

 

Interesting I did not know that. I have never had a problem with it since I purchased the truck and have cleaned the filter many times before. But that's one more thing for me to look into. Thanks.

 

UPDATE: So I just got home and removed the MAF sensor and the air filter. Im going to wash the filter again and try putting it back completely dry and without oiling it this time to see if that helps at all. The MAF sensor does not look dirty (at least the inside doesn't look dirty) as others I have seen. I will still clean it and put them back in once they are dried. I also noticed a smell, some sort of fuel smell but again I don't see any hoses disconnected or cracked to indicate a leak.

 

i don't think your MAF sensor is any good, it shouldn't be open like that on the connector top side, had to check on mine.

 

Hmm, thanks for checking on that. I did find it weird that it was set like that but there isn't any components or anything that might seem that would be harmed by being movable like that. I thought it was just more like a protecting cover. Maybe that is my problem ! $110 part! Would you happen to know how to test it? I already started the truck and disconnected the sensor and it shut off. This seems like it would show that it is working but I could be wrong.

 

Mine opens like that on the top, it is a metal cover that is only attached with the same screws that mount the MAF.

 

UPDATE: So after I cleaned the MAF and the intake filter from all the oil it still had the same idling and hesitating problem. Since I had cleared the codes I waited for the light to come on again. This time I got more codes!!
Now I have the following codes:

P0171, P0300, P0301, P0302, P0304. I believe that those are Random Misfires and Cylinder misfires. Again as I said I did change the spark plugs because I thought the truck needed them but there was no problem. Now that I changed them I have this idling problem and hesitation.

I guess I will be taking the plugs back out and checking them and the packs to see if maybe I missed something or maybe something happened to the plugs that quickly.

I need to get this thing going back to 100% its my DD.

 

Ive never had a problem with my K&N cold air intake. My MAF is spotless but I dont over oil the filter it after cleaning it. It only needs a light coat.

 

Sounds like something's up with the plugs for sure, if this all happened after putting new ones in. Were they gapped properly? New wires as well or using the old ones?

Also which plugs?

 

Well as I mentioned when I did all this the truck ran fine for a 4 hour trip(200+) miles on my way back home. The next day is when the problems began. My truck has coil packs so I didn't think I needed to change those until they went completely out. I know that trucks that have wires it is more normal to change when changing the plugs. I also will admit I did not check the gap as I maybe foolishly trusted the "pre gapped" labeling. I will be checking the plugs, gaps and coils to see if there is anything wrong with them. I will also try and see if I can find any vacuum leaks again.

I want to mention again that the truck is running super bad. I can't even drive to the grocery store down the road because it will start to sputter and almost seem to die. I see other people having these codes and their trucks running fine but that isn't the case. I will try and post a video if I can later to show this. I am starting to worry it could be something way worse than what the codes are throwing.

 

Update:

So today again I go back and do some more looking around. And while inspecting the ghetto air intake that the PO had set in I found this setup. It seems like he somehow by passed what looks like another sensor with like a fuse or something. I was moving the intake around and it seemed like it wanted to die when I did. Now IDK what a stock one looks like but if someone would be willing to snap a pick and show me if there is indeed a sensor missing and maybe if it is critical.

I also rescanned the codes again and it seems to be changing. I had the two original codes then it gave me codes for misfires and cylinder misfires and today it showed all these.

P0100, P0110, P0300, P0301, P0302, P0303, P0304 P0171. Its getting really frustrating for me now since I am getting all these codes at once and then they keep changing.

I checked my sensor and my exhaust to see if it might be leaking and nothing. I checked my hoses yet again and don't feel any leak or any visible cracks. I checked my brake booster(at least the outside of it) and nothing. I really don't want to start buying parts until I know for sure what it might be with some certainty but with the codes changing I cannot narrow it down enough yet. My dad will be making the trip up he should be here in a few hours but probably won't be looking at the truck until tomorrow. He's also bringing me the old spark plugs to see if I can see any damages on those and see if maybe that's where I had a problem.