mojo4x420

I seem to be running extremely rich. Bad fuel economy, carbon buildup on everything. Water temperature sensor seemed fine apon testing, but it was pretty hard to get in there.

Was testing out my afm as per: http://www.4crawler.com/4x4/CheapTricks/AFM/index.shtml

Results:

e2-Vs 67
e2-Vc 180
e2-Vb 280
e2-Tha (temperature reading) 1.77k, about 10 mins later 1.99k, hour later 2.05k
Outside temperature is little under 20deg. Just before sunset it was 2.5kohms

e2-Vs: has a nice curve as the door opens until halfway. Starts at 67, at halfway it's about 800 and then as the door opens more, resistance drops until it hits about 4-500. I was expecting the resistance to keep increasing as the door was opened past halfway.

Any comments appreciated :-)

thanks,
rob.

mojo4x420

anyone?

thook

I believe it's suppose to reflect in a wave pattern...up/down...up/down, but I'm still learning about it myself. In fact, I'm having close to the same issues with my 22RE.

Sorry, I'm not much help, but I thought I'd reply to bump.

ewong

Remember what the AFM is supposed to do.....

show the *MASS* of air entering the engine

Temp affects air density - so there is a temp probe

But the "opening" is "rectangular" in shape.

At small openings, the dx/dt of the change in plate angle yeilds larger changes than it does in larger openings.

Also - air takes on a "fluid" type property as it flows through a constriction.

The "resistance" measurement was an "analog cumputer" to relate voltage across the resistance to a mass of air value.

Thus the resistance is NON LINEAR.

In a modern digitial computer one MIGHT attempt to substitue the flapper angle to air density via actual calculations.. but the AFM is 1960's era tech.
THe calcualtions are made in the lab and translated into a non linear resistnace (but the air mass should be a liner value)..

Also recall that the flaper is L shaped - there is a damper chamber behind the other part of the L - so I dunno what actually happens at larger opeing levels.

In modern EFI - they have gone to a "hot wire" sensor - which gives a MUCH BETTER actual MASS of air value....

hosh

http://personal.utulsa.edu/~nathan-buchanan/93fsm/

this is the FSM. It shows the same as your link.

Sounds kind of like you may have a bad O2 sensor. When they go bad your fuel mailage goes downhill very fast. You run rich and get carbon buildup.

I've had both go bad on my 3vze. When the VAF went it would barely run. When the O2 sensor went it ran rich.

mojo4x420

My o2 sensor passed the tests as posted in the FSM, but I still suspect it might be bad. I get no Vf readings (for testing o2 at the diagnostic port) at startup for a minute and sometimes also at idle when stopped even when warm. I also get no readings at WOT... wasn't sure if that is correct or not.

I have a non-ceramic coated doug thorley header w/ sensor down the pipe where the cat's supposed to be. I figure it's not getting hot enough and I should probably switch to a heated o2 sensor. It passed the FSM tests though so I had figured something else might be wrong.

Should have access to a friends engine sometime this week and I"ll see if his AFM behaves the same way.

ewong

Vf is the super secret Toyota tuning tool... see Jeff Moskowirz (sp) turbo site for the faq on Vf...

o2 sensor "static" tests arent as important as if it "scrolls" through the soich voltage under normal cruise conditions...

Heated o2 has mainly to do with startup conditions/emissions...

If the header cracked (is it wrapped) or has a bad seal it will throw off the o2 readings.. (BTDT)

Your AFM readings (going up and down as the flapper opens all the way) appear to be correct...

Also bear in mind that the AFMs are differnt even for teh 22REs.. (there are variant)

mojo4x420

I tested water temp switch and water time switch and they are all correct.

o2 sensor at the OX diagnostic plug reads good. It jumps back and forth good and if I undo a vacuum hose it reads 0.1v and w/ propane feeding from a small unlit torch into the intake it reads 0.8v. So that seems like it's functional.

Fixed an air leak. Hopefully that's been my problem all along. Hmm, I quick test would be to see if the o2 sensor reads above 0.8v w/ the propane being fed now.

86toyota

Any updates? Trying to diagnose my own problems.

Bigblock

This era Toyota does not use the O2 sensor during idle or WOT.Better check for vac leaks.My 89 w/3vze had a lean/& rich mixture code as long as I had it.I worked at Toyota back then(Y2K) and the shop authority said Toyota can't even fix it.After much testing I couldn't prove him wrong.The light stayed on,it ran great,sux gas,so I said %$@# it!

Fahrenheit 451

I just like to say this a lot, because it happens A LOT on the 22re. Check the TPS first, clean the o2 sensor and clear the ecu while doing it then see if any other stuff is not working right.