Toyota 22RE AFM idle mixture screw adjustment / factory reset - how does it work & what is it doing?

Автокөліктер мен көлік құралдары

This video provides some general information on how the air flow meter (AFM) on the Toyota 22RE EFI motor functions, as well as how the idle mixture / trim screw adjustment factors into the mix.
In very simple terms, when you turn the idle mixture adjustment screw on the AFM, you are tricking the ECU into thinking more or less air is entering the motor; the computer will respond by either slightly increasing or decreasing the target air fuel ratio - as described further below:
1. Turn screw clockwise (CW) = richer
2. Turn screw counter clockwise (CCW) = leaner
But why? When the screw is turned CW, it blocks off the secondary air bypass channel of the AFM. This results in more air pressing on the door inside the AFM and the AFM sends the ECU a voltage reading which indicates "more air" (i.e. the door is being pushed open slightly more) and thus the ECU responds by thinking "more air means we need more fuel" - it then slightly increases the pulse duration of the fuel injectors to supply more fuel.
When the screw is turned CCW, some air - which otherwise would have been pushing the door inside the AFM open further - can now bypass via the channel under the idle mixture screw; this reduces the pressure on the door inside the AFM. The ECU understand this new voltage signal from the AFM to mean "there is less air coming into the motor now" and it backs off the amount of fuel being added to match the perceived lower volume of air entering the motor.
In my experience, 2.5 turns CCW seems to be a fairly decent starting point, if you have lost the original factory adjustment. Alternatively, if your AFM housing still has the original number stamped on it, you can take that number (e.g. 26 or 30, etc.) and simply add 10.0 mm to obtain the original factory depth setting of the screw. For example, if the number you see is "30", then you would add 10 mm to arrive at 13.0 mm depth. A stamp showing "26" would represent 10 mm + "2.6" or 12.6 mm factory depth and so on ("28" would mean 12.8 mm). This depth measurement must be made accurately from the top edge of the screw hole housing down to the flat face of the screw itself - ideally using a digital or vernier depth caliper.
If you wish to gain a more comprehensive understanding of some of these areas, you may want to download the PDF version of the Toyota Computer Controlled System (TCCS) training manual here:
www.autonerdz.com/yabbfiles/A...
The TCCS manual provides a lot of great information on what the ECU is doing in terms of controlling overall engine operation; much of the manual applies to the 22RE motors used in our trucks and vehicles, although the manual itself covers a wide range of Toyota EFI systems (not just the 22RE). The manual has specific information relating to the AFM and its factory idle mixture screw adjustment on pages 18 & 19.
PLEASE NOTE: While I do give some basic guidelines as to "resetting the idle mixture screw near the original factory position", final adjustments for your individual motor may vary and should be confirmed through monitoring of the VF voltage output levels via the ECU (see page 136 in the TCCS manual for more information on this).
Here is the AFM I'm running on my truck and shown in the video. I purchased it directly from Napa Auto Parts:
www.napaonline.com/en/p/NECXT...

Пікірлер: 57

  • @chrislee6691
    @chrislee66917 ай бұрын

    Thanks Ray I always appreciate your videos. I have a 92 of the same truck and the information that you provide has been very valuable. My goal is to have my engine bay as clean as yours at some point. You have def been an inspiration. Thanks

  • @ray5961

    @ray5961

    7 ай бұрын

    Thanks Chris!

  • @regularguy8592
    @regularguy85927 ай бұрын

    btw Ray ole chap your videos are really done well and much help to us all!

  • @ray5961

    @ray5961

    7 ай бұрын

    Thanks man! I really appreciate that.

  • @regularguy8592
    @regularguy85927 ай бұрын

    thanks so much for link to the pdf that is going to be sooooo helpful!

  • @ray5961

    @ray5961

    7 ай бұрын

    You're most welcome. It's a super interesting manual for understanding more about what is going on with the ECU on Toyotas.

  • @cristobalvillalpando7451
    @cristobalvillalpando745117 күн бұрын

    Great video, thank you very helpful

  • @regularguy8592
    @regularguy85927 ай бұрын

    I had a look at my AFM this morning, it appears to be capped of where the adjustment screw should be. My question is is there an adjusting screw under the cap if I pry it off or does mine just not have that adjustment screw?

  • @ray5961

    @ray5961

    7 ай бұрын

    I'm not sure if there is an adjusting screw under there or not. The only thing I know is that the TCCS manual states that those do not require any adjustment and the ECU handles it.

  • @regularguy8592

    @regularguy8592

    7 ай бұрын

    thanks . you know im proly gonna have to pry that cap of just to see lol. I'm most likely going to change my whole system over to Haltech this summer anyway. That would eliminate that whole box@@ray5961

  • @caseyhogan2142

    @caseyhogan2142

    7 ай бұрын

    I also have a capped one, 91 2wd 22re. No number casting either

  • @regularguy8592

    @regularguy8592

    7 ай бұрын

    mine is a 93 and I didn't look for numbers but I will next time I get a chance@@caseyhogan2142

  • @ray5961

    @ray5961

    7 ай бұрын

    @@caseyhogan2142 Interesting. I don't remember if my original (the one I accidentally destroyed) was capped off or not. I'll dig through older pics and see if maybe I can see something. The re-manufactured Napa one is what I have now on the truck.

  • @regularguy8592
    @regularguy85925 ай бұрын

    Ray I just did some checking and on the afm I have around 5v going out from it on pin 3 which should split off at e10 and then supply power to the tps pin1 and ecu thermostat pin 1. Problem is I'm not getting any voltage from the BR-B wire at the tps or the ecu temp sensor. I'm guessing most likely problem is a bad connection at E10 and that is located where wiring harness goes up through the middle of intake so I really cant get to it without taking top portion of the intake off. I'm going to cut BR-B and run new wire to the tps and temp sensor. What are your thoughts on the matter Ray?

  • @regularguy8592

    @regularguy8592

    5 ай бұрын

    disregard all that Ray pin 3 doesn't have voltage I was reading pin 5, was reading print backwards. I went back and ohm out the wires from tps and ecu temp sensor and they were good all the way to afm. Now all that said it does look to me like Pin 3 should have voltage. 12v comes in on pin4 goes through a resistor and I thing a potentiometer then out on pin3 to tps and ecu temp sensor. I'm no electrician am I reading the print wrong?

  • @ray5961

    @ray5961

    5 ай бұрын

    @@regularguy8592 The temp sensor is a resistor that the ECU monitors so it knows the coolant temp and can adjust the flow of the fuel injectors. TPS sends the ECU data regarding throttle plate opening. Down load the TCCS manual in PDF via google.. it will explain a lot of this for ya.

  • @regularguy8592
    @regularguy85925 ай бұрын

    well my afr reading look like what I think are pretty good now every where but at idle and I gave it some thought and think I need to revisit my tps adjustment. First I'm going to verify all the wires are on the right pins then check adjustment again

  • @ray5961

    @ray5961

    5 ай бұрын

    Yeah you definitely want to ensure the TPS is in correct adjustment, otherwise all other bets are off.

  • @regularguy8592

    @regularguy8592

    5 ай бұрын

    well every thing with tps checked out ok so I'm stumped as to why I'm running 10s and 11s afr at idle still@@ray5961

  • @regularguy8592
    @regularguy85925 ай бұрын

    Ray from what I see today my fuel pump has been straight wired and runs any time the ig switch is on, There is no voltage on Fp with switch on or engine running and the limit switch in the AFM has no effect on fuel pump also has no voltage going to said switch. Would this cause my fuel pressure to be high? I have to wonder why they wired it like that something went bad I'm sure. I'm going to try and look into it more tomorrow

  • @ray5961

    @ray5961

    5 ай бұрын

    Fp won't have voltage on it. The Fp line in the diagnostic box is basically just a wire running directly to your fuel pump. If you jump Fp to B+ and turn the ignition on/off - that should turn the fuel pump on and off as well. You can also jump the Fp directly to the 12V + lead of your car battery and that should turn the fuel pump on and off. If the fuel pump turns on and off with your ignition key (no jumpers in the diag box or anything), that usually means the contact points inside the AFM are touching for some reason (maybe the door is stuck from shutting totally?). You can reach into the AFM and make sure the door is swinging smoothly or you can approach it from the top with the spring wheel stuff and make sure it's resetting correctly also. If none of that is out of whack, it could also be that your circuit opening relay has failed in the closed position... so you might want to check that (relay is in the right kick panel area under the glove box). If you look through my videos, there's one or two that shows the wiring harness schematic that controls all this area also. Let me know if you have any other questions and/or what you find over there.

  • @regularguy8592

    @regularguy8592

    5 ай бұрын

    very helpful thanks and I will look into all that father and let you know my findings@@ray5961

  • @user-fo5du7qt6s
    @user-fo5du7qt6s7 ай бұрын

    Can you make a KZread short for you exhaust sound at idle ? Great videos as always 👌🏽👌🏽

  • @ray5961

    @ray5961

    7 ай бұрын

    For sure.. I'll do that soon. I usually only drive the truck once a week, but it's on my list of things to video. Coming soon! :-)

  • @ray5961

    @ray5961

    7 ай бұрын

    Just posted the video for ya!

  • @regularguy8592
    @regularguy85926 ай бұрын

    well I replaced that regulator and pressure is still pretty much the same about 44 psi ,it may be getting down around 40 at wot. I did however figure out I was turning the gear on afm the wrong direction ,now I have it idling around 10 or 11 and it cruises around 14 or so ,wot is in the 15s for a bit then catches up. I'm guessing that's about the best I'm going to get until I replace ecu with a Haltech. I'm going to drive it a while watch gauge and mpg then I might or might not tune on it some more

  • @ray5961

    @ray5961

    6 ай бұрын

    Okay.. yeah that AFM wheel stuff can be tricky all right. Did you happen to mark the OEM location? It's easy to get all out of whack in there with those teeth. It should idle around 14.7 +/-. Mine usually idles well right at 14.7 (1.0 lambda). Sometimes it will drop down to 13.25, but the ECU generally brings it back to 14.7 pretty quick. If the ECU and O2 sensors are doing their thing, then cruising should swing back and forth around 14.7 roughly in one second intervals. 13.8 on the rich side, then swing over to 15.2 on the lean side - back and forth, back and forth while driving. That's how mine operates. If you suddenly go WOT, usually the ECU will become confused for a moment and go 15+ until it figures out what it happening and - like you say - sort of catches up and gets the show on the road; that process can take several seconds until the ECU kicks you back down to more like 12.8-ish range (this is why I added that micro switch THW line hack in that one video - to force the ECU rich more quickly). Basically the Toyota ECU is doing the best it can.. but it isn't gonna be on the job like a HalTech or Link or MoTec ECU will be. Also, no matter what you do with the AFM wheel, the ECU (when operating in closed loop mode) will be constantly battling you for 14.7 some way, some how.

  • @regularguy8592

    @regularguy8592

    6 ай бұрын

    yes I had gear wheel marked. Someone has sniped a couple wires off at the front end of R/B No.2 and I'm wondering now maybe they possibly straight wired the fuel pump so that it runs all the time once switch is on . I'm going to check into that father in the next day or two@@ray5961

  • @regularguy8592
    @regularguy85925 ай бұрын

    Ray I tried jumping Fp to battery and it wont turn pump on. it looks like they have bypassed the efi relay, the white wire with red stripe and the black wire with green stripe have both been cut, The black wire has been tied back into an ignition-on wire and the white wire was scabed in at another placed and white wire has been replaced and run over to AFM. I checked the efi relay out and it is good ,its getting power to pin 5 from the efi fuse and power to pin1 from ign fuse and pin2 checks to ground but I think they cut the wire coming off pin 3 which is a white wire with red stripe. If I pull the efi relay out the truck will crank and run without it. I'm betting they bypassed c6 circuit opening relay too but have not confirmed that yet. The w-r wire coming off the efi relay is also supposed to go to ecu at two places, I'm wondering what they did with that. I have had a problem ever since i bought that truck with the ce light being on and will not flash a code no matter how I try to reset the ecu so maybe that could be related. I wonder maybe the fuel pump relay went bad and they didnt know where it was at could possibly be the original problem. I would ask that feller I got the truck from but I just found out he is making little rocks out of big rocks for the state now lol

  • @ray5961

    @ray5961

    5 ай бұрын

    That sounds wild... the Fp connection in the diag box should be a hard line directly to the fuel pump - so jumping that directly to +12V at the battery should always turn the pump on. Do you have the electrical schematic that I show in my other video? If not, let me know and I can email it over.. it shows all the wiring we are discussing here. When you pull the EFI relay out (which is only 4 pins) nothing should work.. that provides power to the ECU - pull that relay or 15A EFI fuse and the truck should not run (referring to model years 89-95 here).

  • @regularguy8592

    @regularguy8592

    5 ай бұрын

    @@ray5961 yes I have the electrical book for the 93 model which is what the truck is and it takes a bit of studying to figure out the drawings but I think I have it pretty much down now. If its not reining tomorrow I'm going to look into it father, I'm figuring I will have to pull R/B No.2 to figure out what exactly was done and if there is a problem with the box its self and also check that fuel pump relay out I will proly start with it

  • @ray5961

    @ray5961

    5 ай бұрын

    @@regularguy8592 Sounds like something is out of whack. The fact that the fuel pump doesn't run when directly connected via Fp is what strikes me as strange (unless Toyota changed something in the later years - which is always quite possible with Toyota). Anyway, let me know if I can help out in any way.

  • @chad_actual
    @chad_actual7 ай бұрын

    I like to watch your videos before bed because they are the most boring things on Earth. But thank you for your dedication to the Toyota community.

  • @ray5961

    @ray5961

    7 ай бұрын

    haha... I do that too actually

  • @regularguy8592
    @regularguy85925 ай бұрын

    Ray my motor has been egr and fresh air deleted I wonder is that why it wants to run a little rich at idle?

  • @ray5961

    @ray5961

    5 ай бұрын

    that should not have any major impact. The EGR is more or less inert gases, so you can kind of think of it as more or less neutral to the equation. The fresh air suction system primarily introduces air on deceleration (off throttle) in order to help burn fumes and fuel as it hits the cat.

  • @Garbosgarage
    @Garbosgarage3 ай бұрын

    Ray - where did you get the air intake tube that connects the plastic intake tube to the AFM?

  • @ray5961

    @ray5961

    3 ай бұрын

    I bought the rubber elbow from amazon. The rest is factor stuff that was already on my truck.

  • @Garbosgarage

    @Garbosgarage

    3 ай бұрын

    @@ray5961 do you have a link you can drop here in the comments? I'm ready to order and need one.

  • @ray5961

    @ray5961

    3 ай бұрын

    @@Garbosgarage Here's a link for ya. You can search that description on amazon also and find a lot of places that sell this part. I get most of my parts off ebay used or amazon or sometimes the online Toyota parts places. www.amazon.com/QKPARTS-1989-95-Throttle-22231-35030-2223135030/dp/B07217768Z

  • @regularguy8592
    @regularguy85925 ай бұрын

    Ray I see something that might possibly make a difference. The way I read wiring diagram the ecu is supposed to have power all the time, to kill power to it you have to pull ecu fuse. The way they have it wired now is it only gets powered up when ign switch is on so that would reset it every time you turn engine off and back on. I think I'm going to put an inline fuse and run it straight to battery.

  • @ray5961

    @ray5961

    5 ай бұрын

    yeah cutting power to the 15A EFI fuse clears the ECU. Probably not the best setup to have that tied into the ignition switch :)

  • @regularguy8592
    @regularguy85926 ай бұрын

    well I'm still fighting my afr running to rich, idles around 9 sometimes in the high 8s when lightly accelerating it will run around 12 or 13 but if you really push it hard it hits the 15s. I replaced the afm completely and have run that screw way out and adjusted the gear several notches with pretty much no change, I checked fuel pressure tonight and with switch on but motor off I get 44 psi and after cranking engine and running at idle it stays the same so tomorrow I'm going to replace fuel regulator and see if that helps. One thing I did notice was the other morning when temperature was about 10f when I cranked it up first thing in the morning it would idle around 11 until truck warmed up then go back to the 9s. Any one have any any thoughts?

  • @ray5961

    @ray5961

    6 ай бұрын

    At idle you should be seeing around 35 PSI on the fuel rail, so that does sound like either your fuel pressure regulator is not functioning and/or not seeing vacuum. How much vacuum is your motor pulling at idle? Should be around 17-18 in/Hg if everything is okay on the rings, manifolds, etc. Check to make sure you have a good deal around your dipstick. Make sure you are not running a breather on the valve cover to atmosphere. Check for vacuum leaks in general. Also check your coolant temp sender is functioning on the lower intake manifold runner (the one next to the cold start timer one. If that is not working correctly or sending too much resistance to the ECU, it will basically double the amount of gas being pumped through. If you want to rule the temp sensor out, you can jump the pins in the harness itself and drop the resistance on the THW lead to the ECU to zero and effectively cancel out the cold temp fuel coefficient compensation stuff (which could potentially cause your issue). I have a video here which talks about some of it, if you'd like more of an idea of what is happening in that area: kzread.info/dash/bejne/ZH1spKeogdvLnbA.htmlsi=yu5DxnRchhjfXGm- if you have an ohm meter handy, you can also pull a reading off the temp sending unit on the intake runner and see what the Ohms are cold (based on outside temp) as well as what it's at when coolant is above 140 degrees F. Basically when cold you should be reading something like 8k or 10k ohms and once coolant temp is up, you should be seeing maybe 200 ohms or so.

  • @regularguy8592

    @regularguy8592

    6 ай бұрын

    @@ray5961 Vac is running 19 at idle ,new dipstick and tube ,new ecu temp sensor from LC engineering (I may ohm it out if regulator don't fix it) I put a fuel pressure Vac and afr gauge in dash pretty much like you did. I think when I change regulator I'm going to blow that return line out to the tank make sure its not blocked somewhere. Thanks for almost instant reply, it is a nice feeling when you know at least someone is there to help!

  • @ray5961

    @ray5961

    6 ай бұрын

    @@regularguy8592 I try to hit all the comments in 24 hours or less; nothing worse than not having your 22RE running right :) Definitely check the return line. If you have a vacuum pump, try pulling a vacuum on the pressure regulator while the fuel pump is jumped on (Fp to B+ w/ ignition key on). When you hit the regulator with vacuum, you should hear it change tone if all is working correctly.

  • @regularguy8592
    @regularguy85925 ай бұрын

    well today I switched fuel regulator vacuum line to another spot and that brought fuel pressure down to about 35psi at idle but afr still the same at idle around 10 or 11

  • @ray5961

    @ray5961

    5 ай бұрын

    Are you positive your gauge is configured for gasoline? On my AEM gauge for example, I run it in Lambda mode but I also have to specify that I'm using traditional gasoline and not E85 or something.

  • @regularguy8592

    @regularguy8592

    5 ай бұрын

    nothing in the paperwork for this gauge referring to e85, its setup in afr mode and the thing is its running pretty close to 14.7 when driving its just at idel its running too rich@@ray5961

  • @regularguy8592
    @regularguy85925 ай бұрын

    Ray Toyota didn't do that someone has been rewiring things sometime in the past and from what I see they had to have pretty good knowledge to make it work although its not working as intended. It appears to me they lost power to the W-R wire and the B-G wire so they clipped them off on the topside of connector A4 (shown as A-4 inside a box on the prints) So they spliced the B-G wire back into another wire on the connector beside A4 that has 12v when switch is on and that leg of the B-G wire goes back to the ecu. Now the W-R wire they spliced in two wires to take its place, ran one over and daisy chained it to the 3 vsv valves and then over to the AFM. The second wire they spliced in in place of the W-R wire they ran to the ecu at B+ AND +B1. Now the problem may be that they didn't finish out the job because I don't have power on +B at the Data link connector box when ign switch is on. Now I just realized tonight that could also mean I do not have power to o2 sensor because the print shows the W-R wire has a splice E9 (inside an octagon) where it branches over to O2 sensor. Am I reading that right?? If so that could explain why my afr is off and could also possibly explain the check engine light being on all the time possibly. Now the reason I think they lost power to the R-W and B-G wires is the stubs are sticking out of connector A4 now and have no power on them even thought the efi fuse and relay are appear to be working, I need to get a look at bottom side of R/B No.2 but I'm not sure I can flip it over with it all wired up. Its also strange that my book give a detailed wiring diagram of J/B No.1 but only give you a drawing with basic component layout on R/B No.2 Now all that said I also had to replace a section of wire and the connector for o2 sensor a while back too. it looked like at some point wire got on hot exhaust pipe and partially melted connector and wires. Now it had been repaired before but looked pretty ratty so I re-did it, Maybe there was a short there that took the efi fuse out and stopped the fuel pump from working, Tomorrow I will check power to o2 sensor first thing see what I have ,I may even disconnect the thing and see what my afr does

  • @ray5961

    @ray5961

    5 ай бұрын

    Sounds like fun times over there. I wonder why they rewired so much?

  • @regularguy8592

    @regularguy8592

    5 ай бұрын

    I wish i knew😢😢@@ray5961

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