afm help needed
 

This all started when my exhaust manifold was getting cherry red. I started by jerking the cat and it was say about 50 percent plugged. I took out the cat and put in a piece of exhaust tube and tested it and it still got to hot.

I said screw it and took it to the same local import mechanic my family has been going to for 20 years. We have never had even the slightest problem with them. They do some tests and tell me the afm is out. They say that the afm is causing the motor to intermediately run rich and lean in kind of a teeter-totter effect. He is always very fair and tells me that a new one is 190 bucks from Napa and recommended I just go get a used one from the wrecker.

I pay him the 60 bucks for doing all the tests and drive the truck home. I pull the afm and test the resistance as service manual says and everything checks out. But it does say that if a complete failure occurs the resistance at the polls may still be correct but the engine will run rich or lean or the fuel pump wont turn on.

So now here is the questions:

1: Can the afm be busted even when the resistance at each pair of points is correct? 4crawlers page has a note saying that the only way to test for this "complete failure" is an air fuel mixture gauge. The shop used one of these and says it is bouncing lean then rich.

2. The wrecker wants 100 bucks for a used afm. But when he looked it up on the computer he looked for 22re 4runners and pickups in the right year span and there was none in the local yards.
If I remember right isn’t the afm of 22re supras and celicas the exact same and a direct fit?

someoen must be able to give me some advice so my yota can live once again and get outa the garage.

Resistance checks aren't accurate. The best way to test it is with a graphing multimeter. You watch the voltage trace while driving.

Whats your O2 sensor reading when your truck acts up?

Go on fleabay for the AFM. I got a rebuilt one for $75. Works perfect.

Cherry red exhaust means high EGTs.
Most common cause is timing or improper air/fuel.

I'd check the output from my 02 sensor and verify my timing... It could be the AFM, that's true.. but check these things first.

That is what the mixture is supposed to do, it is an averaging system. If you look at the O2 sensor output, it should bounce between rich and lean about 8 times in 10 seconds, swinging between ~0.4volts to ~0.8 volts or so at 2500RPM.

ok well got me a used afm today and i can sure feel a difference in power i nthe motor but the exhuast still glows frigging red hot. I am beginning to wonder if it has always dont this but i have never noticed because i havent ever opened to hood at night. Anyone else with a 22re ever open the hood at ngiht after driving to see if its red? The timeing is good and the afm and o2 are new now. And the cat is gone and no exhuast is plugged.

mine never glowed red when i had my 22re

did you ever look at it at night when it is dark? mine seems normal during the day but at night the thing looks like a glowstick

yes i have never red

well i am stumped haha but i dotn want to put on my new header until i get thsi hot exhuast issue worked out

Did you check your 02 as 4crawler mentioned above? Did you check your timing?

the shop checked the timing and told me it was ok. The 02 sensor is only a month old but I have not tested it. I will check the sensor as 4crawler said and the timing tomarrow because it is late right now. I really dont think the timing is off because the thing runs like a top and has great power but i guess you never know.

Please put your cat back on, or get a new one. Cough, air, cough