School me on O2 sensors for the 87-91 tbi trucks

[Vbb199]

Ive heard of different styles of o2 sensors. I believe i have one failing on my suburban (i thinm theres only one last i looked, maybe 2). Upon starting the truck lately, after a couple minutes if idling, it will randomly turn off, and ill have to crank and crank, and fight a stumbling motor by feathering the gas until it finally runs, following a bunch of stinky, unburnt gas.

Theres also the issue ive had of idle changing out of nowhere for no reason. Hot or cold engine temps, thermostat open or closed.


This isnt a cts issue i dont think. Wiring has been verified, i recently replaced the sensor, this issue was present prior to sensor change.

For those of you without knowledge on my truck, engine doesnt have excessive mileage, tps is good (irrelevant to idle), iac is fine, and i recently also performed a relearn on the idle (issue was present prior to that as well) IAC was replaced maybe 5 months ago.

Only things not changed is MAP and O2.

Im suspect of either one, but possibly inclined to think given the miles on my clock, and discussing with the p/o of the truck, the o2 and the map are the original components from 1989.


Given the Change in temps outdoors (winter), the density of the air has changed, thus possibly leading to a faulty MAP.

I also have zero engine codes

Moving forward. Current o2 is 1 wire.

I have heard of these "heated" 3 wire o2 sensors

What is the difference, and which should i run, and why?

Thanks.


Oh, and i have no pics @Rusty Nail

 

[CSFJ]

Is the truck throwing an o2 code? If I remember correctly, the default on the system is to run rich if the sensor fails. That shouldn't cause the truck to shut off. I would suspect the map before the o2.

 

[Vbb199]

Is the truck throwing an o2 code? If I remember correctly, the default on the system is to run rich if the sensor fails. That shouldn't cause the truck to shut off. I would suspect the map before the o2.

No sir, no engines codes at all. Thats what confuses me. Its not a constant problem, but an intermittent one.


Its heavily gassy when i finally get it to fire up after dying.

The dying only occurs when the engine is bone cold, and warming up, but before the thermostat opens, rushing the CTS with cold water.

The idle changing occurs at any stage (open/close thermostat)

 

[Poppy 87]

The 3 wire heated sensor was introduced to enter closed loop operation earlier, thus lessen emissions by entering the more desired lean running condition. These early emission systems are archaic at best, if it was my truck, I would run the diagnostic for MAP sensor first then the O2 if no concern found with MAP

 

[Vbb199]

The 3 wire heated sensor was introduced to enter closed loop operation earlier, thus lessen emissions by entering the more desired lean running condition. These early emission systems are archaic at best, if it was my truck, I would run the diagnostic for MAP sensor first then the O2 if no concern found with MAP

So, run a 3 wire? Or just a simple 1 wire since it doesnt really matter (if i find the o2 is faulty)

I want maximun performance out of my engine, but i know earlier o2 sensors do not really have a big hand in overall engine performance and reliability like newer engine o2 sensors do.

 

[Poppy 87]

I'm not sure the old ecm would even recognize the O2 heater circuit. You are correct about overall effect on performance. If I found the fault to be the oxygen sensor, I would replace it with an OE type, probably ac delco these days.

 

[Vbb199]

I'm not sure the old ecm would even recognize the O2 heater circuit. You are correct about overall effect on performance. If I found the fault to be the oxygen sensor, I would replace it with an OE type, probably ac delco these days.

Got it, thanks poppy

Ill do an evaluation of my map with my mulitmeter later

 

[CSFJ]

If you can see what the temp sensor(s) are reading, that would be worth a look too.

 

[Vbb199]

If you can see what the temp sensor(s) are reading, that would be worth a look too.

Youre referring to voltage? Or temperatures?

 

[austinado16]

Also, there are different designs in the tips of the 02 sensors, based on how close to the heat of the exhaust port, the sensor is placed. A sensor that mounts closer to the ex. port will have slots in the tip that are more less open. A sensor that mounts further away, will have slots that are more open. That's what helps the non-heated sensors get hot fast, and remain hot enough to be active and keep the system in closed loop.

 

[Rusty Nail]

Hi.
It's pretty tough to get a one-wire O2 to throw a code i'm thinkin. However their service interval is 60,000 miles -right? 30?
Sure as hell aint no 100k!

Hold on. Ive got the part number.

They're CHEAP now. Used to be $100 a pop now they're not even $50...The overtly rich condition may indicate you're barking up the correct tree.
Buy a BOSCH brand, **** everything else. Check the length of the wire and run ya a dab of VASELINE in the plug.

Prolly make a night and day difference. Is this the same truck that just got the new distributor with the loosened knock sensor by chance?

Dick. Go take a pic - gah!

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[Ricko1966]

O2 sensor isn't even a factor until the engine is warmed up.The engine would even run with it disconnected it would just be in default mode O2 sensor is so easy to check, but I'd bet money it's not your problem. Disconnect if the problems still there than look for another problem. O2 sensor put a meter on it with the engine running, create a vacuum leak to make it lean watch your gauge.Spray carb cleaner down the throat, make it rich,watch your gauge.Undecided take it out put it on a bench put a meter on it and hit it with the propane torch. It's that easy.

 

[CSFJ]

Youre referring to voltage? Or temperatures?

I was thinking of a temp reading, depending on what kind of scan tool you have available.

 

[CSFJ]

Hi.
It's pretty tough to get a one-wire O2 to throw a code i'm thinkin. However their service interval is 60,000 miles -right? 30?
Sure as hell aint no 100k!

Hold on. Ive got the part number.

They're CHEAP now. Used to be $100 a pop now they're not even $50...The overtly rich condition may indicate you're barking up the correct tree.
Buy a BOSCH brand, **** everything else. Check the length of the wire and run ya a dab of VASELINE in the plug.

Prolly make a night and day difference. Is this the same truck that just got the new distributor with the loosened knock sensor by chance?

Dick. Go take a pic - gah!

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See how much better with pix? It takes 5 seconds.

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Not hard at all to throw a code. Had an '88 that would do it all the time if you spent any length of time with the cruise set.

 

[Rusty Nail]

I had to fix one before because the wire had melted on the exhaust and dude butt -connected the wires together but the CCC didn't like that connection.Had to fix dude's wire and sell him another O2 - because he had cut the plug off.
BUT! They will be in a pipe LONG PAST service interval being as lazy as the OP - that cant spend 5 seconds - - bein lazy and not setting a code for it is what I was gettin at. AND new ones make a TON of difference in my experience. Didn't all that ish start with complaints about throttle response or some ****? Don't ignore the O2 - they're cheap now.

That One Wire O2 reads and changes fuel mixture at the rate of five times per second - if i'm not mistaken.

Huge difference.