lambda dead?

lambda dead?

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smighall

Original Poster:

105 posts

169 months

Wednesday 10th September 2014
quotequote all
I've finally managed to get my tuscan talking to the laptop so quickly checked things out and lambda 456 is showing a constant 0 volts. It also shows as ok. With the car running the adaptive are well into the 30.

123 flicks between 0 and 1 volts generally around 0.8 and the adaptive around -2 to -4. Only had it running briefly so was cold but does that indicate lambda 456 is dead?

Cockey

1,384 posts

227 months

Wednesday 10th September 2014
quotequote all
This is taken from the diagnostics manual:

LAMBDA 1 & LAMBDA 2

Lambda 1&2 show the signals from the lambda sensors on each set of three cylinders.

Lambda1 is the front three cylinders (ie. cylinders 1,2&3) and lambda 2 is the rear three

cylinders (ie. 4,5&6 ). After starting the sensors will take at least 30 seconds to warm up,

before they will read correctly . Once warmed up, the lambda signals should switch between

approx. 0 & 1-1.5 volts. 0 volts shows that the fuel mixture is lean, 1 volt shows that the

mixture is rich. The rate of switching will alter with engine speed, and the percentage of time

spent rich relative to lean will alter with engine load. If reading is a CONSTANT 0 V, check

sensor for proper connection, and sensor heater wires for continuity (6 ohms between white

red wires)

NOTE: Lambda sensors are supplied with 12V on the red wires ONLY WHEN THE FUEL

PUMP IS RUNNING, the WHITE wire is earth and BLACK the signal.

Can download it from here:

https://docs.google.com/file/d/0B4pzeL_TBDYeOGFmNG...

stevieeg

269 posts

129 months

Wednesday 10th September 2014
quotequote all
It does sound like a knackered sensor.

A sign of health in a digital lambda sensor is the number of cross counts (i.e. the flicks between detecting lean and rich) a good sensor should do this at least once a second.

It sounds like your sensor has gone and is constantly sensing (lying) lean, pushing the adaptive map to it's highest level of positive adaption.

Have you reset the adaptives yet to see if you run smoother as a result?




stevieeg

269 posts

129 months

Wednesday 10th September 2014
quotequote all
http://www.nobleforums.com/showthread.php?10587-Ad...

Quite a good general discussion on MBE adaptive mapping.

twinreal

300 posts

154 months

Wednesday 10th September 2014
quotequote all
Diagnostic software will also show adaptives at around 30 and an AFR fault when the lambda sensor is disconnected. So i would check the connections before changing the sensor itself.

smighall

Original Poster:

105 posts

169 months

Wednesday 10th September 2014
quotequote all
Checked the connections again earlier and all seems ok there. Will pick a new one up from Racing Green tomorrow. Looks like it's a bit of a PITA to get to it without removing the battery etc.

Will find out later in the week when i go to change it over.

smighall

Original Poster:

105 posts

169 months

Monday 15th September 2014
quotequote all
Changed the lambda at the weekend.....now running MUCH better, smoother idle and better across the rev range, as expected really.

Does now show up the shunting on light throttle so probably put the throttle body bearing mod on the list for winter.