Hi Guys,

Looking for some help. Got a MY00 Uk Classic. Had it for 5 years now.

Noticed lately that my fuel is disapearing very fast .

Car is used everyday and driven the same way Monday - Friday But Gets a blast now and again .

Could this be the Lambda Sensor ?????

The only symptom i have noticed is the fuel consumption. Idle is fine and no hesitation.

Any help or info would be great.

Cheers

 

Lambda sensor probably the likeliest explanation going on info provided, but there are others. From this point it seems you can speculatively buy a new one, fit it, reset your ECU and see if things improve, or get your car plugged into something with some flashing lights.

Did it have any difficulty passing its last MOT emissions test btw?

 

A drop in fuel consumption is typical of a Lambda sensor failing/failed. It will overfuel, but can otherwise appear fine.

You could try disconnecting it to see if it makes things any worse, if it stays the same it will be the Lambda sensor.

They are available to buy: AZTEC PERFORMANCE ONLINE STORE - WHOLESALE PRICES DIRECT TO THE PUBLIC - Lambda/Oxygen Sensors :: Lambda/Oxygen Sensor - Subaru Impreza Turbo (Inc WRX, STi)

Next day delivery if ordered before 4pm.

 

Got my full exhaust swaped for last MOT so it passed ok.

Car got mapped a while back so resetting the ECU isnt a road i want to go down. Does it have to be reset when a new lambda sensor is fitted ?

Left my car ticking over at work a few months back as i went inside for a minute, guy at work who knows a bit about basic cars mentioned that he thought my car was running a bit rich by the look of the exhaust fumes but didnt think much of it at the time.

Would the car throw up a fault code if the lambda sensor is gubbed ???

 

ECU reset won't effect the remap.

No need for reset after fitting a new lambda.

I've never had it throw up a code when it's failed. Just pick up on the symptoms, such as running rich and higher fuel consumption.

 

Do you still have the emissions test result sheet? Sometimes you can see clues to early O2 sensor degredation in the numbers.

Why not? Can't see the underlying logic of your caution there. It's not like resetting the ECU will undo the remap or anything like that, the changes your mapper has made are stored in non-volatile memory, not RAM.

The only thing you lose over a reset are the learned ignition/fuelling/etc corrections - which will be relearned as you begin driving the car again.

It's good practice to reset the ECU after changing any faulty sensor - as above you will get rid of any learned corrections, which is a good thing if there's a chance that any of the learning is based on erroneous inputs. Much better to reset the thing and make it relearn from scratch.

In practice usually not. They normally degrade and under-read (to a greater and greater extent) rather than outright "fail". The ECU has no way to know the sensor is degrading so it responds by putting in more and more fuel under closed loop running.

You can get an idea how fecked (or otherwise) the sensor is by monitoring its output voltage under boost, either directly with a voltmeter or with an AFR gauge. If you don't want to go that far, just replace the sensor, reset and see what happens to your fuel consumption.

 

Cheers Splitpin & Bob'5.

Will try to find my emissions results but at the moment i dont have it to hand.

Thought if i reset the ECU then i would loose things done in the remap

How do i go about resetting the ECU then

 

Either leave the battery disconnected overnight/few hours or have a search on here for the plug method

 

got a lambda for your motor for sale if you need it baz.