Hi, what damage could be done if you run your car with the Lambda senor un-plugged. Reason being is that there is hesitation between 2000-3000 rpm and ive done a search and its pointing to the sensor.

Ive stripped and cleaned all the other sensors and checked for air leaks and nothing was suspect.

If it is the sensor where is the best place to buy one from?

My car is an MY98 STi version 4.

Cheers

Paul.

 

No real side effects, but it won't pass an MOT!

You may need to do an ECU reset as its likely to have learnt bad Lambda adaption values.

Simon

 

Running your car without the Lambda plugged in will make idle, low speed and cruise running very rough indeed. Your ECU relies on the lambda sensor for trimming AFR's in closed loop mode. It could potentially have the effect of running your engine too lean or too rich and even at low loads and rpm's that could still cause detting.

The only way around that is to map your ECU for open loop running right the way through so it relies solely on Primary fuel maps for all running. Baring in mind it's a 98 there's no way to map it so you would have to buy an aftermarket ECU to do that. Very expensive workaround for a simple issue of sensor replacement.

Easy option is leave the lambda sensor plugged in and put up with the hesitation until you replace the sensor. It will run better that way than unpluggin it baring in mind most of the time you're pootling about the ECU is running in closed loop mode. If you haven't had a check engine light come up on the dash indicating a knackered sensor then it could be something else causing the hesitation like coil packs, spark plugs, boost pipes leaking somewhere etc...

Get a scooby specialist to plug their laptop in and run some diagnostics to check the running of the car either on a rolling road or on the road before you go splashing out for uneccessary component replacement. Might save you some big bucks and a large headache in the end.

 

And your basis for these assumptions?

The open loop mapping as stock on Classics is just fine, the O2 sensor is only used for fine trimming for emissions, lots of people have run them with no O2 sensor without problems at all....

Simon

 

Second the rookie. wrx555 is clearly over cautious. The worst that will happen is that it will read lean and therefore add fuel - this will likely help the hesitation you're having.

Lots of people have run without and it works fine. You may however get a check engine light eventually.

 

Running without a Lambda sensor has no benefits. It makes the car run rough off boost and consume more fuel.

I just changed one on my Rover. Fuel consumption went from 250miles per tank to over 400!

We keep lambda sensors in stock. PM for price.

 

If you have a faulty sensor the unplugging it is actually the right thing to do, the ecu recognises a faulty sensor even though it doesn't throw a CEL, it disables its closed loop function if it does see that. As long as you DO NOT reset the ecu the car will actually probably run more smoothly. Ultimately it may notice, especially if driving at constant speed (motorway) but the CEL is only a warning and its not detrimental.

The only time an ecu will throw a cel for a faulty sensor is if it has seen enough engine drive cycles with the sensor fault present to recognise it, since most of us drive and move the throttle aroud in doing so the most likely time to see a cel is when steady state cruising.

cheers

Bob

 

Looks like Bob has provided the answer

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Shaun