If You’re Not Doing This to Your Engine You’re Stupid

If You’re Not Doing This to Your Engine You’re Stupid


rev up your engines today I’m gonna show
ya how to fix a car that’s running too lean this Toyota rav4 just came over
here the check engine light is on it’s got the code p0171 which means the engine
is running to a lean now unfortunately there’s whole bunch of things can do
this so you have to start logically going to the hood and look at the most
logical things first now running to lean means that the combustion inside the
engine is burning at too low a ratio meaning either it’s not getting enough
fuel so it runs lean or it’s getting too much air and it’s running too late now
one of the common thinks for that is a vacuum leak if a hose is come off if a
gasket gets broken and sucking air into the engine it’ll run to lean so that’s
the first thing you look for and if you’re really smart and have just a
regular scan tool you can get a $40.00 one that does this it’s got the code
that means there’s data store so you go to the section on your computer it’s got
freeze frame data here it is here view freeze frame data so you look at you get
tons of information there and the main thing when you’re running to lean is you
want to look at when did it occur it will show you the speed of the car if the
speed of the car is zero and that code tripped when it was idling that
generally means it has a vacuum leak because when the car is idling the
engine is moving that fast so it has a little less vacuum pressure if you get a
vacuum leak and you’re idling with the low vacuum pressure that’ll set it down
quite a bit percentage-wise can make it run lean than it trips the
code realize that the codes are tripped when the computer sees like 20% or more
off value so it’s got to be a reasonable amount this lean code tripped when
you’re going 65 miles an hour odds are it’s not a vacuum leak because
it’s 60 the engine spinning like mad and it’s got tons of vacuum pressure it’s got a
little vacuum leak it’s not gonna bother it that much because the leak is gonna
be a smaller percentage of what it is when the engines only idling a much
lower vacuum pressure so if it did occur at lower speeds are at an idle you want
to look all around for vacuum leaks and on these Toyota’s it’s often a vacuum
line it comes off a lot of times the one back here behind the air filter gets
pulled off and somebody changes the air filter but that one’s not bad sometimes
they come off of the PCV system but that’s on nice and solid
if you can’t see or hear any vacuum leaks when the engines idling use your
ears and if you hear it sucking and look around you can do like I showed in
the previous video get a little wd-40 with the spray nozzle spraying around
and if you get say on the intake manifold and it starts to change the
idle you know it needs an intake manifold gasket but the cold tripped on
this one when it was going 56 miles an hour so it happened at a higher speed
now if you got a running to lean at a higher speed and you look at the trouble
code freeze frame data it happening at higher speed in this case 56 miles an
hour odds are it’s not a vacuum leak but it’s
something in the fuel injection system you could have a clogged filter you
could have a weak pump you could add a bad mass sensor those are the most
common things to check for so the first thing you do would be check the fuel
pressure now here’s a warning if your fuel filter is easily accessible change
the fuel filter first because fuel filters if they clog up guess what after
the filter the pressure will go down make it run lean because you don’t have
enough pressure to spray the fuel injectors correctly so if you do have a
fuel filter that’s easy to access go ahead and change it now my old celica
hey it’s just two bolts you take off your place of filter so that’s what I
would do but on this modern rav4 fuel filter is inside the gas tank now
you don’t have to drop the tank but you got to take the back seat out then you
have to take the excess panel then you got to pull the fuel pump assembly out
because the filters built in there now Toyota generally wants to sell you the
whole fuel pump assembly for six seven hundred dollars with the filter built in
you can buy a filter but in this case hey you’re not gonna just change the
filter on the lark because it’s such a pain in the butt so we’re gonna just
check the fuel pressure it’s supposed to be between 44 and 50 pounds per square
inch just test it and if that’s what it is well then
we don’t have to worry about changing the fuel filter because the pressures
coming out fine anyway since it’s such a job to get an air change the filter
we’re just gonna check the pressure on this I’ll get my fancy fuel injection
tester chip and I do mean fancy because Toyota over the ages they’ve been kind
of a swine about checking fuel pressure they never had test valves on them most
of them don’t anyways modern anyways they all went their way it’s cheaper to
make it but you got to get a special adapter you hook it on the fuel line and
then check it with a gauge you’re gonna have to buy the special toyota adapter
which isn’t cheap so you might want to pay somebody else to do this in this
case it’s fine it’s about 50-51 pounds so in we know the fuel pressure is
good so it’s not that it’s not getting enough fuel next thing to check is the
mass sensor mass airflow sensor now in these Toyota’s a notorious are getting
dirty and giving false readings so they can make them ron lean it’s right here
some thing to get to right here there it is now you can only clean these things
with mass airflow sensor cleaner don’t try anything else gotta leave no
residue yeah this stuff costs a lot sometimes these cans are like 10 12
bucks but they last for a long time you don’t need a much cleaner cleaner you
just remove it from the vehicle just find plugs you got squeeze the heck
out of it then remove the two Phillips screws that hold it in place they just
screw out and the sensor wiggles and comes out now clean is pretty easy
there’s a little mouthpiece here right in here you want to clean it and there’s
also one inside so for that you spray it in the front then you spray it on the
other side of the hole and it cleans the stuff on the inside and here comes a
part that everyone hates patience something hardly anybody has these days
they’re very volatile cleaner you’re gonna do it outside so you’re not
breathing it you want it to completely air dry so there’s no residue of vapors on it when you start it up because if you clean it put it right in and start
it off a lot of electricity goes through here those vapors can short things out and even worse
don’t clean them on the vehicle if you take the hoses off and clean it from the
inside then you got all that vapor in there don’t
do that take it off and clean it most cars it’s not that big of a deal getting
it out and like I say if you clean it wait about half an hour because I’ve
seen people who didn’t they were in a hurry or cleaned it inside and then boom
the electricity hit the vapor burnt things out they need to buy expensive
sensor do it externally let it air dry that way you can’t hurt anything after
half an hour so just put it back in its hole the same way it came out make sure
it’s seated in because there’s an o-ring in there and you put the two screws one
and two and of course don’t forget to snap the electrical connection in wow
that was close the hood down erase the codes just push erase codes yes this
now erases the code so the codes gone and take it for a good road test
now sometimes codes take a long time to come back but take it on the highway in
town maybe half hour trip if the light doesn’t come back on then you just drive
it and after or 2-3 weeks that doesn’t come back you fixed it in this case
since this is a 2.5 litre engine when it’s idling the data the mass airflow
should be somewhere around two and a half grams per second that it’s flowing
when it’s at idle in drive so I checked it and it was our two point six
four which is perfectly fine for this if it had been really low like one point
six that would mean it’s giving it way too little gas and if the reader have
been really high like four point seven then it would give it too much gas but
then it would be running rich not lean if it’s running below the parameters
then it’s gonna run lean because it thinks there’s less air coming on so it
gives it less fuel now in this case when they get dirty they often give a false
reading we’re hoping and that’s what it is after the half hour drive it didn’t
come back on you’re really like I say give it a couple of weeks because these
things can be very slow with picking things up but if it never comes back
then you know it was just a dirty mass airflow sensor, so now you know how to
fix a car that’s running too lean in this case also took was a few squirts of
mass airflow sensor cleaner so if you never want to miss another one
of my new car repair videos, remember to ring that Bell

About the Author: Michael Flood

100 Comments

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  2. P02C2 Cylinder 11 Fuel Trim at Max Limit. This means that cylinder 11 is too lean and the computer is trying to compensate by adding more fuel? The thing is, this is a 5.7 Hemi 8 cylinder in a 2012 Jeep GC.. So why is it tripping a code on cylinder 11?

  3. how do you dry you mass air flow sensor fast?….. hand it to Scotty while he's talking…… his typically spasmodic hand waving around will have it bone dry in a jiffy

  4. Ummmm…lean codes can take a while to find….he makes it sound easy. It is not. If you have little experience and think your gonna fix a lean code….good luck.

  5. Yeah about that. My 03 Outlander had a small evap leak for a year. My mechanic was actually angry when I brought it to him to check the code. Well yes. yes there was a vac leak. My gas tank/filler neck was rusted to pieces.

  6. I'd like to see a video of your neighbor discussing what they think about their neighbor yelling in his driveway daily.

  7. It’s bad news is the fuel pump & filter are inside the gas tank. The good news is Toyota made access so the fuel tank doesn’t have to be dropped. Yay!

  8. I replaced my Nissan Maxima 2001 fuel filter @ 150k miles. It was located in the gas tank, had to take my back seat out, remove the access panel & pull the fuel pump/filter assembly out along with the fuel gauge lever. I forgot to put the rubber grommet back on the new fuel filter so the car wouldn't start. I became a real expert that day in replacing a fuel filter, and probably lost a few brain cells from the gasoline. The worst part was the previous generation had the fuel filter in the engine bay so it could be easily replaced.

  9. Thanks Scotty!
    I didn’t know you had to spray fluid inside the MAF sensor. I re cleaned it and I think it fixed my p0171 code. Also hit the fuel filter bolts with blaster just in case I gotta do that.

  10. Skotty – An engine generates highest vacuum at idle. Closed throttle plate. Anything above iddle drops towards the minimum at WOT. Makes sense?

  11. Hi Scotty I have a question for you. Someone told me that during oil changes he drains his engine oil and fills it with 3 litres of diesel and runs it for 2 or 3 three minutes to flush his engine off gunk etc. Is that a viable option for flushing your engine?

  12. I put a Kand N filter system on a car. The Kand N filter element is supposed to be sprayed with oil after cleaning. The oil crapped out my mass air meter. Car started running terribly, cleaned my mass air meter and put the stock air cleaner system back on. Problem solved!

  13. Hi Scotty first of all thanks for all the information you gave in your channel it’s great, my question is totally different than this video ha ha ha ha, I got a car that says premium fuel recommend it, do I really have to put premium fuel on it or should I put any regular fuel

  14. But to check for a clogged filter you should test the fuel pressure while driving. Or at least with the engine on and high rpm.

  15. hi Scotty, not liking how your calling a lot of your viewers STUPID, as we watch to find out your helpfull info but you are actually calling us stupid before we find the wright way , just to let you realize.

  16. "vacuum pressure" lol. The first thing you do is clear the code and see if it resets. That's called Verifying the Condition. Sometimes computers glitch.

  17. I had a Pontiac doing hard shifts and no codes. Finally threw a code for maf and all I did was clean it with that exact spray. Fixed the mag and hard shifting. Something about the computer not being able to figure out the shift points when getting wacky maf readings so it just did forced shifts with a best guess.

  18. You said let the cleaner dry for a long time. I was think, at least 24 hours. Half hour is nothing! another great idea Scotty! Thanks.

  19. Hey Scotty, I have a Tacoma 3.4L with codes that indicated transmission solenoids were bad and the speed sensor also, I replaced the trans solenoids and also replaced the speed sensor. The truck still won’t shift into 3rd or fourth, what’s my problem, by the way the Tacoma has 101 thousand and change, what could the most probable problem be? Thanks Scotty

  20. Get a basic scanner like a Foxwell N310. That can read live data. Instead of crawling all over the car looking for a problem. Check fuel correction. You can check fuel pressure with the scanner. You can view grams of air going through the maf. If fuel correction is way off at idle but cleans up goin down the road, its a vacuum leak. Check maf, at idle the reading should be roughly what the liter the engine is. 1.6 engine? reading should be around 1.6. If its way off or spikes, you know maf is going bad. Dont even have to get your hands dirt.

  21. As the adage goes,…"If you don't have the time to do it right the first time, how will you find the time to do it over?" [Wink.]

  22. My the knowledge you have in vihicle's, makes me feel like Schultz on Hogan's heroes and his"I know nothing".
    Really your a good honest machanic, a real treasure

  23. Next video. How can a 2001 BMW X5 4.4i have 200 plus thousand trouble free miles on it when I have been bad mouthing X5's for years. lol

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