Why do you guys need oxygen sensors and we don't ? (1 Viewer)

Joined
Mar 12, 2018
Messages
571
Location
Doha Qatar
Hey guys, I am creating this thread not because I have a technical issue, just for the sake of curiosity. I hope you guys don't mind that I am bringing up a different series land cruiser in the 80 series section, its just that there is no other section with 1FZE experience.

When I say FJZ100L I mean: Middle east spec 1998-2007 100 series land cruiser which came with the GEN 2 1FZE same as the LC105 expect its IFS.

So I have been reading posts here in the 80 series section about oxygen sensors, and I cant help but wonder why many or all posts that I read claim that the 1FZE requires oxygen sensors to "run properly". While all of my experience with land cruisers equipped with the 1FZE (the GEN 2, or the 105 series/FJZ100L 1998+) run without oxygen sensors at all.

NOTE:

1. All GEN 1 1FZEs on 80 series land cruisers here in Qatar come with no oxygen sensors from the factory. I know this for sure because when I went to buy OEM exhaust manifolds for my FJZ100L last year at the Toyota spare parts store, the salesman asked me weather I wanted a manifold with a hole for the oxygen sensor or not. 1998+ FJZ100Ls come with the ports for oxygen sensors while 80 series manifolds do not come with oxygen sensor ports.

2. Out of all the people I know who own the FJZ100L run no oxygen sensors including me, the significant portion are running long tube headers however some run the factory exhaust manifold with the hole for the oxygen sensor plugged.

NOTE: I do understand the importance and the function of upstream oxygen sensor. It measures the air fuel ratio and feeds the info to the ECU to ensure "proper" or optimal operation.

So my real question is, why is it that an older, and simpler 80 series with the GEN 1 1FZE require a oxygen sensor to run properly, and the newer 1998+ FJZ100 with the *newer* GEN 2 1FZE does not ?.

I also read that the 80 series triggers a check engine light for you guys when there is a problem with the oxygen sensor. For us both the FJZ100L and the 80 series do not trigger the check engine light without the oxygen sensor. However when you install a OBD scanner, it does prompt an error that there is a fault with the oxygen sensor.

More importantly they seem to run perfectly fine ? No rough idle, no excessive fuel consumption. No signs of a excessively rich air fuel ratio (by checking spark plugs). The issue is I have not tried to buy a new O2 sensor and connect it to identify if there is a noticeable difference in how it runs. This is what I will be doing in the incoming week. I bought a new O2 sensor and will be wielding a whole in the exhaust and plugging it in to test.

My speculation to why: Middle east, Qatar especially does not have strict emissions requirements at all, which is why they are hardwired to not require the oxygen sensor. During the production of the FJZ100L (1998-2007), Qatar did not even have any emissions requirements.

Part number of the oxygen sensor that I purchased from Toyota spare parts: 89465-60260

Link: 02 Oxygen Sensor For Toyota Landcruiser FZJ100L 1998-2007 89465-60260 | eBay - https://www.ebay.com/itm/02-Oxygen-Sensor-For-Toyota-Landcruiser-FZJ100L-1998-2007-89465-60260-/164031753726

Image of the codes that appeared after scanning with an OBD scanner yesterday. Basically the same result of all the FJZ100Ls that I have scanned (in exception to the crankshaft position sensor). The MAF which is located in the intake manifold is the only component that is required(of course, otherwise the ECU would be completely blind). Unlike the 80 series which has a MAF attached to the air cleaner. The air temp sensor is an additional small sensor available in the FJZ100Ls which is never actually used here. Nobody runs it or so it seems from the hundred of cruisers I have seen.

File_000 (1).jpeg
 
Last edited:
Joined
Mar 12, 2018
Messages
571
Location
Doha Qatar
Bingo we have a winner!
True we could end it here lol, however that still does not explain why people are claiming it is needed to run properly. Maybe its just a different ECU (fuel map, ignition timing, etc) configuration.. for you guys in the states

it is still interesting though that the engine is not running overly rich. None of the spark plugs I have inspected have shown signs of a overly rich air fuel ratio. MAF must be doing a great job doing all the heavy lifting.
 
Last edited:
Joined
Mar 12, 2018
Messages
571
Location
Doha Qatar
More a spectator in this thread, but I would guess the ecus are setup differently such that one's with an 02 sensor depend on its input for emissions reasons.

I had no idea there were 100s out there with 1fz and ifs
Yes that makes sense Toyota must have hardcoded the ECU to require the O2s to be functioning to ensure the emissions are kept at a min.
 
Joined
Feb 2, 2004
Messages
11,025
Location
Washington
Correct, there are different ECU’s for countries that don’t require the OBDII emissions controls. For 1FZ’s in those areas the O2 sensors help the truck adjust fueling so that it isn’t too lean or too rich.

For countries without OBDII, the 1FZ just runs off of the fuel and load tables, in the ECU. I am sure it runs fairly rich since that is safe. Oddly though the O2 sensors can catch problems like a failing injector, intake air leak, etc. I am kind of surprised Toyota just didn’t use them on all the 1FZ’s. I guess they save some money not using them.

For a truck like yours, I would definitely add an aftermarket wideband O2 sensor in the exhaust.
 
Joined
Mar 12, 2018
Messages
571
Location
Doha Qatar
Correct, there are different ECU’s for countries that don’t require the OBDII emissions controls. For 1FZ’s in those areas the O2 sensors help the truck adjust fueling so that it isn’t too lean or too rich.

For countries without OBDII, the 1FZ just runs off of the fuel and load tables, in the ECU. I am sure it runs fairly rich since that is safe. Oddly though the O2 sensors can catch problems like a failing injector, intake air leak, etc. I am kind of surprised Toyota just didn’t use them on all the 1FZ’s. I guess they save some money not using them.

For a truck like yours, I would definitely add an aftermarket wideband O2 sensor in the exhaust.
Great answer.

I did not know O2s had the capability to catch errors.

Before I attempt running a aftermarket wideband O2. I am curious to see if my vehicle runs differently with or without the factory O2 sensor. I imagine without getting technical it would be difficult to observe a difference.

So I will be taking it to a dyno jet before an after to see if having an O2 + air temp sensors running will in any way shape or form change the engines performance. It should be interesting. (BTW, bone stock GEN 2 1FZE with a full exhaust no cats).

Three runs without the sensors and three runs with.
 

Howard705

TLCA 5505
SILVER Star
Joined
Feb 1, 2013
Messages
1,448
Location
Central Illinois
Open loop/ vs closed loop. It will adjust as needed. reason heaters were added to O2s is for staying in open loop and going in sooner. Im sure better fuel mileage also.
 
Joined
Feb 2, 2004
Messages
11,025
Location
Washington
Great answer.

I did not know O2s had the capability to catch errors.

Before I attempt running a aftermarket wideband O2. I am curious to see if my vehicle runs differently with or without the factory O2 sensor. I imagine without getting technical it would be difficult to observe a difference.

So I will be taking it to a dyno jet before an after to see if having an O2 + air temp sensors running will in any way shape or form change the engines performance. It should be interesting. (BTW, bone stock GEN 2 1FZE with a full exhaust no cats).

Three runs without the sensors and three runs with.

This is going to be interesting, because I am not sure your ECU will know what to do with the O2 sensor? I would imagine if it was engineered to run without one adding one would be superfluous. But it is curious to me that you guys don't have an intake temp sensor. The MAF has to have a temp sensor to work. The additional temp sensor you are talking about might be for some other feature. Kind of like how there are 2 coolant temp sensors, 1 for the ECU and 1 for the dash.
 
Joined
Mar 12, 2018
Messages
571
Location
Doha Qatar
This is going to be interesting, because I am not sure your ECU will know what to do with the O2 sensor? I would imagine if it was engineered to run without one adding one would be superfluous. But it is curious to me that you guys don't have an intake temp sensor. The MAF has to have a temp sensor to work. The additional temp sensor you are talking about might be for some other feature. Kind of like how there are 2 coolant temp sensors, 1 for the ECU and 1 for the dash.
I am positive that the O2 sensor will be recognized by the ECU. while the 80 series cruisers don't come with O2 sensors here, I failed to mention that all 1998+ FJZ100Ls do come with a catalytic converter and an O2 sensor from the factory. It's just that its rare to find a FJZ100L here with the O2 still installed.

The FJZ100Ls also come with air temp sensors on the factory airbox standard from the factory. Although same as the O2 sensor, it is rare to spot one that still has it installed.

So I am sure both would function to some degree.

We will know for sure by the end of next week.

A picture of what most oxygen sensors look like on FJZ100s here, disconnected with the sensor acting as a plug.

IMG_0541.PNG


A picture of what most air temp sensors look like, also disconnected lol.

IMG_0543.PNG


MAF Sensor (on intake manifold)

IMG_0540.jpg


A picture of the air temp sensor that fits on the airbox.

IMG_0542.PNG
 
Joined
Dec 10, 2007
Messages
7,626
Is there an unused factory O2 sensor connector (or two) available on your vehicle's engine harness?
 
Joined
Mar 22, 2017
Messages
127
Location
SoCal
Okay, I'll take a shot at this.

Technically all you really need for EFI to work is engine speed and throttle position, commonly called Alpha-N strategy. Motorcycles used, and in some case still do, this until fairly recently. Above that would be speed density which incorporates a MAP sensor to further add fueling/timing accuracy(mostly for the sake of lower emissions and added fuel economy) and beyond that Mass Air Flow which has the advantage of automatically compensating for altitude and humidity changes. Adding more inputs such a IAT(intake air temp) increase the accuracy and allow them engine to run closer to ideal air/fuel for fuel economy and to a lesser extent power production. Adding a oxygen sensor allows the computer to verify fueling is correct in real time, called closed loop monitoring.

Essentially, what you want is to run as lean as you can for each operating conditions to keep emissions low and power as close to max while keeping things safe for the engine. The more inputs you have the easier it is for the computer to accomplish but that comes at the cost of added complication and failure potential(think of high end German cars, they have a lot of very complicated systems but also suffer from very low reliability because of it, the more parts you have the more potential for things to go wrong).

If I had to guess, I'd say that vehicles spec'd for middle eastern countries there was more of a emphasis on reliability than emissions/fuel economy due to potential operation in very remote areas, the relatively low cost of fuel and the relatively low air pollution problems(or the lack of concern over it). It would also allow for less complicated computers and that would keep costs low by allowing for simpler circuitry and software(no code needed for the the additional sensors or the failure effects management if those sensors fail) as well as simpler wiring and the obvious cost saving from not having the sensors themselves.
 

Users who are viewing this thread

Top Bottom