Is there anything wrong with running an impreza turbo with the O2 sensor unplugged? Can this cause damage? will it affect fuel economy? etc

Reason I ask is that I've just taken my car for a drive with the sensor unplugged and it feels much smoother from the off with no sign of the hesitation/surging problems that my and some other 802 ecu'd cars suffer from.

TIA
FC

 

Anybody know?

 

With the O2 sensor unplugged at cruise it will use more juice, but make no difference when giving it some as the car will be using the MAF for fuelling duties.


Jim

 

OK, I can handle the extra fuel useage and would plug it back in for any long journeys, just like to know if any damage can be caused.

 

Over time, yes. It will do bad things to your oil & the oil's efficiency will be affected.
Most likely that the lambda sensor was just faulty? They don't last very long! Well, 30,000 miles, but there's no point in the service schedule that they are swapped, so you may have a very old one...

 

The sensor is quite new actualy, only been on the car a few weeks. I guess if there is the slightest chance of damage it'll be getting plugged back in.
Shame realy as because I only travel about 5 miles to work the car is only just warming up and going well by the time I arrive, thats why I was going to leave it unplugged just for the day to day traveling to work, it makes it so much smoother from cold.
Cheers
FC

 

FC,

Have you tried cleaning it at all? - I had a few issues with mine earlier in the year, turns out the covering had come off and it was caked in old oil/dirt etc. After some WD40 and some very difficult cleaning I patched it all up again and sealed it.

Fingers crossed but up to now, no problems at all.

 

What MY car is this ?

If you consider the afr that is run under boost then the slightly richer afr on cruise that unplugging the lambda sensor is going to give is pretty insignificant. The car feels smoother purely becuase its not running closed loop and so is marginally richer.
When carrying out a remap of the factory ecu on MY99-00 cars then I always unplug and remove the lambda sensor so as to replace with a wideband, the cruise fueling is normally no worse that 0.93 lambda and quite often virtually stoich on most cars.

 

Bob the car is a MY00, I figured this had something to do with the open/closed loop thing as I've read similar posts on this subject, I don't understand it though.
Any excess fuel consumption I can handle, it was damage that I was concerned about. Are you aware of any possible damage occurring with running the car with the O2 sensor unplugged?
Regards.

 

No "damage" for as long as the fueling is in or around the range mentioned, you may end up with a CEL though depending on the residual voltage that is on the ecu pin with the sensor removed. (usually 0.38 volts)

 

OK thanks for that Bob, I'll only leave it unplugged for short journeys, to and from work etc, and will plug it back in for any long trips.
Cheers

 

Crazy idea #1024

How about a switch in the cabin to disable the Lambda when cold? Could be a bit like operating a choke, like in the good old days, you could then switch it back in when the engine is warm. I'd guess that the wiring and switch would have to be VERY low resistance so as not to affect the voltages involved.

F

 

Good idea Floyd.

Although you may not have to worry too much about switch resistance.

Although the voltage levels are low, given that the sensor is going straight to the ECU the currents are probably in the low microamps/nanoamps region. Hence a few ohms in a switch is not going to signicantly drop the voltage (ohms law )

Put an milliameter in the line to check before fitting switch.

Rich