4.6 won't go closed loop.

Mogwyth · Jan 15, 2011

Right we can't get the old girl to go closed loop, this means we are getting about 10mpg, reduced power and occasionally poor running.

Lambdas were fixed at .5 so we have swapped them out for new ones and they now flip between .4 and .8 but no difference to the running. No other errors are showing, we have swapped out the MAF for a known working one no difference.

Any thoughts, bear in mind it's a 4.6 on stock ECU.

eightinavee · Jan 16, 2011

What are you reading the ecu with ? The switching threshold for the Oxy sensors is 0.420V so it looks like your sensors are seeing the rich mixture thats causing the poor consumption.Will the sensors go down to 0v on overrun or do they stay still ? Where did the sensors come from - I've seen some from Euro car parts that did a similar thing,fitted exactly,correct plugs etc - but just gave wierd readings.

Mogwyth · Jan 16, 2011

Garage std diagnostic kit. Garage are telling me they go from .4 to .8 as far as I am aware they don't got to 0. Sensors are genuine parts from Rimmers in LR boxes.

Cheers.

eightinavee · Jan 16, 2011

Good that they are proper sensors,cheap ones just confuse the issue.What worries me is the 0.4 bit - if the ecu is not seeing a signal less than 0.4 it will keep trimming richer - giving your poor consumption.
I think the best way forward is to scope the sensor output wire - the black one on the sensor if poss.Failing that a multimeter,just to see whats going on.
I'm a bit suspicous of standard garage scanners,I've lost count of the number of times they have led a tech up the garden path with wrong readings....

Mogwyth · Jan 16, 2011

eightinavee said:
Good that they are proper sensors,cheap ones just confuse the issue.What worries me is the 0.4 bit - if the ecu is not seeing a signal less than 0.4 it will keep trimming richer - giving your poor consumption.
I think the best way forward is to scope the sensor output wire - the black one on the sensor if poss.Failing that a multimeter,just to see whats going on.
I'm a bit suspicous of standard garage scanners,I've lost count of the number of times they have led a tech up the garden path with wrong readings....

Thanks, what I am probably going to do is get it up to the local (27 miles away) independent LR specialist and get them to do a diagnostic, I beleive they have Autologic LR diagnostics.

Mogwyth · Jan 22, 2011

Right we have had the old girl on Testbook and all clear

Would the open loop running, and no fault codes point to a faulty ECU?

4.6 won't go closed loop.

Mogwyth

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eightinavee

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Mogwyth

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eightinavee

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Mogwyth

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Mogwyth

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