(Solved) Odd Rev Pattern + Check Engine Light

2018 Tacoma, TRD Sport,
Manual Transmission,
100k km / or 60k miles.

Engine Codes:
P0455 - Evap large leak detected
P0441(7E) - Evap incorrect flow detected
P07171 - Bank 1 System too lean
P0174 - Bank 2 System too lean
P117B Test failed

Replaced fuel filler cap,
Reset codes,
Then recorded this video
(all in neutral, at first coasting, then on the brakes)
https://youtu.be/ASR4wt56zEg

 

video linked https://youtu.be/ASR4wt56zEg?si=aooh4h2jToEzlV3k

 

was the fuel filler cap the reason for those codes?

 

I don't believe the cap change fixed it, because the engine is still revving strangely like it was before replacing it.

Codes haven't popped up again yet (it's been 1 hour), but they seem to appear once every few days. Every time I try doing something (Fresh tank of fuel, clean the MAF sensor, oil change, change fuel cap), then clear them, so far they just keep coming back not long after along with the weird revving.

 

You need to address the lean codes before worrying about the evap system

Look for a vacuum leak

Is the evap purge valve leaking vacuum with the engine running?

 

what is that based on “You need to address the lean codes before worrying about the evap system”? I thought lean code is from air/fuel mix, not the cause of the problem but the result.


How do I find out if it’s leaking vacuum?

 

Going to install new purge valve today or tomorrow and see if that fixes it

 

I'm not sure what's going on with your truck, but it sure seems like you are just throwing random evap system parts at it hoping to solve the problem. That approach will get expensive fast!

 

Fuel filler cap won't cause a "large leak" code unless it's completely missing.

 

Take the hose off that goes from the canister to the purge valve and check for the presence of vacuum on the canister side of the valve. The valve should be closed completely unless commanded to open by the computer. So any vacuum reading at all indicates the valve is leaking. Also unplug it so it can't turn during your testing

 

Yep, at a certain point it would be cheaper to let a professional look at it

 

It was more of a rhetorical question

 

Actually swapping those parts worked lol. Thanks anyways.

 

I can’t believe it’s…