Air filter wasn't properly sealed for 2-4 months.

2005 v6 4.0L
Thought I properly sealed my air filter, only to check a few months later that it wasn't. Drove around 2000Kms (1250 miles) before i noticed. Seemed to lack power, fuel economy Seemed brutal. What do you guys think?

 

Make sure it's sealed up proper and go drive it. Does it fix the issues? Decent chance they were just a poorly calibrated butt dyno.

 

I can't imagine the additional/unfiltered airflow would affect power or fuel economy so much... but, maybe one or both threw off the MAF sensor? Did you get a "check engine" light?

I would not worry about damage unless you were driving very dusty roads the whole time. In which case, change the oil and clean the TB and MAF sensor. And make sure your air filter is properly seated

 

Sealed it up (triple checked this time) and hit the highway.. couldn't tell just yet if it made a big difference.. might have to give it a day to see. Where I live there's been a lot of snow and cold dry weather. Sand on the roads but not that dusty. Couple long distance trips tho so hard to say.. let's say my truck is pretty dusty right now so don't feel to good about it.

 

And the check engine light has not come on

 

After only 1,250 miles your oil should still look fairly good. If its really dark and dirty looking wouldn't that be a sign of extra contamination getting into the engine?

EDIT: Nevermind, realized you checked your air filter after 1,250 miles... not an oil change.

 

Due for an oil change anyway.. smelt a little burnt but wasn't black

 

Change engine oil and filter. Cut filter open and inspect. Send oil sample for analysis if worried.

 

Your fine

 

Have you done the charcoal filter delete? https://www.tacomaworld.com/threads/cheap-free-mods.4838/page-4#post-46273 If not, the charcoal filter will block any large particles from going into your engine. Not sure why there's a performance loss though.

 

Because the CPU is getting conflicting info, with the air filter not sealed the MAF sensor is not correctly metering the amount of air entering the engine, making it run lean, the O2 sensor is seeing that it is running lean and telling the CPU to richen the mixture to get 14.7-1 AFR.

 

When I first installed a K&N filter I didn't seal the box at the back and immediately got a check engine light. I'm surprised you didn't get one. Should be okay, but make sure it's sealed up now.

 

I haven't taken the charcoal filter out. I figure that stuff is in there for a reason..

 

^It's there to absorb fuel vapors flowing back up the intake in California.

That's only true if the leak is downstream of the MAF sensor. The air filter is upstream of it.

 

Ahh, I'm unfamiliar with the intake system on the 4.0, I've seen a few but it's been about a year since I have.

 

The air filter is always upstream of the MAF sensor in all the vehicles I've seen.

 

Yeah, brain fart on my part, I was visualizing the intake on my truck with the filter being at the top of the block like the 4.0

 

@Locks1587 try cleaning the MAF sensor. Truck is 12 years old after all. Follow this video if you haven't done it before, except use MAF cleaner instead of electronics cleaner: