Is it possible to disable an 02 sensor on an OBD1 (1988 fsuper duty)? If so , how is it done? I know on a custom exhaust system it is done . Thanks!

 

Um, what? Why would you want to disable 02 sensor function? You like getting 6 mpg? The Heated Exhaust Gas Oxygen sensor, or HEGO, samples the exhaust for air/fuel ratio and makes corrections to the fuel trim. But you knew that, right?

 

The O2 sensor manages the engine. I don't think you can run without it.

 

You can definitely run your truck with the o2 sensor disconnected from the harness. You will see a slight drop in mpg (nowhere near 6mpg, don't let people scare you). Basically the computer will run itself on a predetermined set of values, rather than taking constant input from each of the sensors. Essentially like driving a truck with a carb.

You may be able to throw a resistor in there to trick the computer into thinking its hooked up. Or a ecu tune is always an option. In the meantime, you will be fine with it unplugged. I've done it in the past for short periods of time with no real noticeable loss.

 

Without the o2 sensor the truck will not run very good, it will hardly idle and it will get close to 6 mpg. After I installed my longtube headers i ran it for a bit with no pipes or o2 sensor and i actualy had unburnt gas dripping from my headers. If the o2 sensor is not hooked up the computer runs the truck full rich

 

Leave it be, it's there for a reason, so the truck runs correctly. People usually want to eliminate or trick downstream (post cat) O2 sensors on OBDII vehicles because without a cat you will get a CEL with a 420 code for catalyst efficiency below threshold.

While you're at it unplug or wire in a resistor to the IAT sensor so it thinks it's -40* so the ECM commands more fuel for maximum power!! [sarcasm]

 

I had the o2 unplugged from the harness on my 5.0 for just over a week, waiting for my new o2, and I noticed a small drop in mpg. Nothing major... but your engine will run more efficiently in the long run with it hooked up.

 

If it does there is way more wrong with the setup than disconnected O2 sensors!!!!!

 

Rear/Downstream O2 Sensors are only for the monitoring of the effectiveness and health of the catalytic converters and have no impact on the performance of the engine.

 

14 years later...these OBD-1 trucks do not have an O2 sensor after the converter. Most have only one BEFORE the converter to sense the air/fuel ratio. Disabling or removing it typically causes a pig rich condition.

 

I would reply but I would be wrong.

t
uses an oxygen sensor, since it's not evil.

 

1) Crankcase oil dilution

2) Excess carbon buildup in the cylinders

3) Spark Plug Fouling

4) Increased Fuel Usage

5) And ... well ... No One Here Seems To Worry About Pollution, So ...

 

Even the aftermarket retrofit EFI SYSTEMS have to have an upstream O2 SENSOR.

Same on a highly calibrated CARB SYSTEM.

 

To add to this zombie thread is the fact the O2 sensor only trims the fuel mixture slightly. I don't think there is ever a time where the manufacturer tunes the engine 'pig rich' only to rely on the O2 sensor to trim it back to normal. The factory tune is usually pretty darn good and therefore the O2 sensor should not work really hard. There are times when the EVAP system is causing the mixture to be too lean/rich, but that is about the only time the EEC-IV would be really far off of perfect. I don't know why Ford would program the engine to run too rich/lean if the O2 sensor is not online. I do know, O2 sensors tend to short out and when they do, the EEC-IV thinks the engine is running lean and therefore will keep adding fuel until it runs 'pig rich'.

As far as I am concerned, O2 sensors are a maintenance item. Swapped before they fail.

The O2 sensor is not monitored when the engine is cold, over 3,800 rpm, or at full throttle. The emissions testing was not monitored back then. I suspect today's guidelines are much more strict.

 

Quote:

I don't know why Ford would program the engine to run too rich/lean if the O2 sensor is not online.

The ECM/PCM has to see many parameters (sensors) to ensure correct (designed) fuel/ignition curves.

One would be initial cold enrichment.

The system has to have a sniffer(s) that is fully functional.

An overly rich mixture will cause O2 and CONVERTER fouling ($$$)