Good luck. If you think you need any input, feel free to post here....or wherever.

 

hmmm, i need to get on that afm testing and test my tps...

 

thook- You are the man! Good solid tech like this is what got me hooked on YotaTech in the first place.

Now I just log in to watch you and Death Cougar hurl insults at each other!

 

You mean DeathLoser? Bahahahahaha!!! (Hope he reads this....)

 

BTW, I thought I should probably clarify my statements a little for anyone who may not understand.

The amount of voltage current through a given circuit is directly proportional to the amount of resistance. The less resistance along the circuit, the greater the amount of voltage that is able to travel through......depending on the source of voltage and the capability of the circuit, of course. And, likewise, the greater the resistance, the less voltage.

So, if the vein circuit is rising in resitance as the flapper opens, the amount voltage is accordingly lowering....until about midway of opening when resistance begins to steadily drop off again. And, of course, voltage begins to rise again telling the ECU to richen fuel. The "wave pattern" that the FSM hints to. Explains partially why you begin to get worse mileage the more you put you foot into the throttle, eh?

 

which is it... voltage or current?
less resistance means more current can flow at a given voltage...
or higher voltage can pass with less current. Vane?

 

Abe I'm hurt. Not a single post in my thread. Lol

 

Yeah...vane...lol!

Less resistance...more voltage. I"m not an electrician, Abe. So, the terminology you can stump me on, but I'm just trying to explain a little how it appears to work according to the meter and what i've read on the tech pages. In other words, I see what you're saying, but for all practical purposes nevermind my use of the word current.

 

no sweat, just trying to razz ya

 

Ya got me, then...lol! <<<dzzzt!>>

 

this thread kinda helped open my eyes to possible malfunctions that could look like 02 sensor problems, im kind of a toyota tech, kinda meaning i served with toyota for about a year, have owned an 02 tundra 4x4, 85 corolla ae86, and currently an 06 tacoma 4x4 sport, and this 87 4runner now. my light comes on while im on the freeway, cruising or when im passing up a car, and it'll go away and come back intermittently. Did anyone try to test the 02 sensor itself to see if it was malfunctioning? i didn't see you guys mention testing the o2 sensor itself, i just picked up a bucket 87 4runner with the 22re and it gives me the five flashes indicating it to be a problem in the 02 sensor unit, i have only one o2 sensor on my truck, and its also a single wire, a reference for the computer, and thats it, no multiple wires, its not a heated o2 sensor. it comes on while i'm cruising on the freeway at higher speeds, or during or after passing up cars. and when i was testing the o2 sensor, according to all data, with the engine speed at about 2500 rpm, with a lab scope hooked up to the correct diagnostic terminals, and was expecting to see the o2 sensor working, but it wasn't. i noticed the check engine light also came on during the testing. so this is what i came up with so far, the truck is a piece of . that hasn't been driven in years. hasn't been registered since 02, and it is now sept of 08. i checked at the diag link, jumped at the terminals, got like a reading of 0.06 volts. steady no fluctuation, most likely just the energy and signals waves in the atmosphere, and the shaking of the truck. i pulled the 02 sensor connector off, and even measured it there, got an even smaller reading like 0.04 volts when i tested directly at the o2 sensor. I am pretty sure now that it is the 02 sensor, pulled it out and examined it, lots of rust and stuff. im hoping the bosch will work for me, i'll repost and hope this will help someone out, if they run into code 5. because i've looked high and low for this code, and noone seems to have it, and if they do, its irrelevant. so either, my testing is wrong, or the 02 sensor is toast. i live in california, and this is a no no. i have also hooked it up to a 4 gas analyzer, and the hydro carbon reading is up high, around 120 ppm around idle. i think im allowed around 70. so its definitely running rich. new plugs, wires, will recheck, and see what it looks like. also went in, correctly timed it, and adjusted the idle speed.

 

Ok, i paid 37.99 at autozone for a bosch oem style o2 sensor, and it came with a semi thick gasket for the oxygen sensor, and it went on without a problem, and my check engine light has gone away, but what sucked is, i took it out to the levee here in sacramento, and got a trespassing/moving violation ticket testing out my four wheel drive, sucked. oh and to clear anything up, my 4runner has the 22re and automatic transmission, and i haven't tried to take it past 80 mph, but im sure it could, its not as bad as some say it to be. i drive 65 to 70 mph.

 

Back from the dead!

I also have a code 5 - 87 4runner, 22re manual, 1-wire o2 sensor.
Light only comes on after longer periods of acceleration, then coasting while in gear. (usually around 2000-2500rpm). MPG and power have steadily been decreasing. Was 22 mpg, take a hill in 5th, now 16, barely make it in 4th!!! Exhaust smell has richened, so I first suspected the Catalytic converter. removed it, and it I can still see light through it at all angles (187k on it!).

This thread helped a lot, so I ordered a new Denso sensor from amazon. (32$ http://www.amazon.com/gp/product/B00...ef=oss_product) Should arrive later this week.

I'll post back my results.

 

What finally resolved my O2 code issue was a new airflow meter.(See AFM testing thread started by thook). I'd tried a number of things, and I do recall actually testing the sensor. Not sure why I hadn't posted about that, but nevertheless.........that wasn't the problem.