Toyota gas mixing

Hey all,
I am getting to the point where I am doing final assembly of my gasifier to my 1989 22re Toyota. There are a lot of better auto mechanics out in the world than I, so I bring this question. The 22re has the Air flow meter (others of course call them MAFs) in the air cleaner. The air cleaner sits on the drivers side of the truck, and there is a plastic tube over the radiator to the plenum. I have a mixing chamber built to replace this plastic tube to tie the wood gas into the system. What I need knowledge on is this; if you would say disconnect this plastic tube or if it were even cracked some the truck will not run because there is not enough vac being pulled against the AFM. So when the AFM is not being activated does anyone know what it is telling the computer not to do? I planned on replacing that plastic tube with my mixer with 2 valves in it. One from the air cleaner as to regulate the air blend, and one from the gasifier to shut that off when not in use. So if I restrict, or limit the air going through that AFM and it is not functioning and telling the computer whatever it is telling it how can I over come this? Some may suggest running the woodgas through the air cleaner and through the AFM, this I did not want to do. The air cleaner shape, size, as well as location, just don’t make it that doable. I also didn’t think it would matter to do this because when you regulate how much air your blending into the woodgas you still have the possible problem of is it enough flow to make the AFM function and not tell the computer something. Also didn’t think it smart to run woodgas through the meter. How to clean it and keep it functioning seems like it would be a real problem. I also don’t know if I will have to modify my PCV system, but this I might be able to handle, but if anyone has any input on that also I would welcome it.

I hope I phrased my question so it can be understood and I appreciate any help some of our wise mechanics can give me. Man, give me an old, old car without all the electronics or just give me the mechanical repairs, and I can fix all day long. But ask me to diagnose electronics, computers, sensors, etc ; its just not something I have taken the time to learn.
Thanks in advance. I want to get her running before Argos. It is doable if I can get this figured out. I thought about waiting to fire it until Argos. It would give us all a fun project. I am so close though I am not sure I could wait even that long ! :o)
Thanks all,
David S

Hi DavidS I cannot give you specifics and hopefully a been there Toyota PICKUP guy will pop in.
I can give to a thinking direction to work from.
The “M” in MAF was for Mass mesuement ot actual air flow. Yous is correct as an Air (volume) Flow system. Yours os Japanese NipponDenso manufatured unter licence from Robert Bosch Germany the developers. They called this a Vane air flow system. Vane is pushed into mivement sweep by the air flowinf past it. It is attaced to a 3-4 even five finger electical sweep aroung bands of resistive carbon tracks. Why all of the multiple wires coming out of it. Could be designed to do different tings as need through each electrical tract circut.
ONe is electric fuel pump shut off or allow. This was so you would not be pumping/injecting gasoline flooding a non-air sucking motor Same cirsut also acts as US Federally mandated fuel shutoff for a rolled over vehicle.
Cranks - no fuel pressure/flow on any of these the quick test was to finger bump the vane off of it’s closed stop to see if it would gthen give pump and fuel flow. NO AIR FLOW AND YOU WILL HAVE NO PUPM POWER. And depending on the vehicle maybe not even spark.
You really, really need a manual on this specific system or you will be guessing on the rest. Even an expereince pick up guy could get trapped mis-informing on a regional specified sysem on these.
Nope. You definatly do not want to run corrosive woodgas theough all of that pot metal castings.
Some systems on these will even use one circut to have the computor modify the spark timing.
Some of these AFM’s even incoreated the air density pressure (baro) and the intaked air temeperature sensor functions.
You really need that manual or a one time specific vehicle model susbscription sign up to one of the online info services like All-data.

If a simple function system set aside STILL PLUGGED IN with no air flow should give fuel pump and pressure and spark with the vane propped open. Computor will only give the fuel it “thinks” is needed for the simulated air volumn flow. Should at least get you started up and running to be able to switch over to woodgas.

Steve Unruh
Steve Unruh

Hey DavidS read here:
Cheer up. You have one of the limited function simple ones.

Hey Steve,
Thanks for the article. I had actually found that same one after I made the post. Now I just need to read it through slowly about 20 times and my brain will start to wrap around it.
David S

Well David look at it this way. Instead of trying to have to learn ALL electrinic fuel injection possibilties that have been used (quite an Elephant now!) you only have get a working undertand of one system - yours. A one meal of elephant meat. That’s doable by 90% of the people willing to learn to Internet.
Once you do get this then you will have the principals down that will apply needed to be know for all electronic fuel injection systems.
These have been on US production vehicle beginning in ~1967. 100% into US sold, with a computor, sensors since ~1985. 100% with full elecronic fuel injection since ~1990.
Cheer up. It is MUCH easier to learn a Tech once it’s had decades of simplifing shake-out. I sat aside on personal PC stuff for 2 decades myself untill 1994 and it has shaken out and simplified to something non-nerd usable. Saved thousand spent and spent more time out DOing in the real world instead until then. You havne’t wasted time. Just waited for the need to invest in yourself.

Ha! But now 2013 - time for most here to get on with the new millennia and quit pining away for the good old days of 1967 and older. My eyes water and my nose plugs up every time I get stuck behind one of those way-backs machines at a 4 way/6way interchange. I Do Not miss the hacking and coughing, seriously polluted air and water and crappy fuel economy from back in those “good 'ol days”. They sure do not miss the sickening ankles deep horse shit, flies, dead animals, maggots; the smells of it and coal smoke stench that was every City back in the Gay 90’s (1890’s) either. Au-tow-mo-biles, self-powered trucks, and electric trollies were the God’s send. Precise, clean burning electronic fuel injection has been ours. Easy to see this just going to many cities in South America, SE Asia and Africa. “Air so thick with pollution you can cut it with a knife.”

Steve Unruh

Steve and whoever is interested,
I got my gas mixing chamber done yesterday and I was amazed at what I found. The valve for blending in the air I put in line between the air cleaner and the mixer can be shut down quite far (almost off) and the truck still runs. It don’t take much air to pull the AFM open. I don’t think it was going to be a concern anyway because I think the only thing it ties to is the fuel pump, which I will want off anyway when running on wood. I already have a switch to turn off the fuel pump relay, so I think I might have it figured out. Thanks Steve for your input and encouragement. I thank Mike LaRosa also as he has been helping me with this by PM also.
A little more assembly now, and I should be ready to test fire!
On a side note, I wish I had a decal with three capital Bs’ on it. I may finally be able to use that acronym myself.
David S