Lamdas - P38

storm · Nov 10, 2008

Hi,
Can anyone please help. Engine runs fine but co2 is too high for MOT & dash show 9.2 mpg when doing 60mph, drops to 5.4 when in traffic.
Replaced air flow meter, no improvement. Took it to speciallist who hooked it upto his book thing, cleared Lamda fault, road test, rechecked- no faults found, but readout for both lamdas is 0 even when engine is reved. Both lamdas were replaced 14 months ago, but did not improve mpg then.
Any suggestions please.

bill_gj · Nov 10, 2008

Not familiar with your exact oxygen sensor - is it a single wire, three wire or four wire connection?

eightinavee · Nov 10, 2008

If both Oxygen sensors are outputing 0v all the time this is a rich reading.Will they putput 5v with the ign on but with the engine not running ? The bloke that did your diagnostics - did he try an adaptive reset ? Does your car have LPG ?

storm · Nov 10, 2008

eightinavee said:
If both Oxygen sensors are outputing 0v all the time this is a rich reading.Will they putput 5v with the ign on but with the engine not running ? The bloke that did your diagnostics - did he try an adaptive reset ? Does your car have LPG ?

Only checked it with engine running, at idle & revving it to approx 3300rpm. Don't thing he did an adaptive reset, but did clear some faults before road test, they didn't show after test, but then he found the output was 0v. It does not have LPG.

storm · Nov 10, 2008

bill_gj said:
Not familiar with your exact oxygen sensor - is it a single wire, three wire or four wire connection?

There are either 3 or 4 wires, I think their are 3 wire. Its a 4.0SE auto P38 '95, If that helps.

SORRY, ITS 4 WIRES.

rewmer · Nov 10, 2008

If you have 10 mins a bit of wire and a multimeter you can check what the sensors are doing. Find the black wire from each sensor and attach a length of wire long enough to reach the cabin. Then using the multimeter between each wire and a suitable earth ( I use the ciggarette lighter socket ) you can monitor the outputs individually. Under normal driving they should cycle between 0v and .8 every second or so - it helps to see this if your meter has a bar graph on it - under heavy acceleration they should go to .8v (rich) and stay there whilest you are giving it some and on the overrun go down to 0v (lean). You say they are only two years old - where they genuine parts or patterns ?

eightinavee · Nov 10, 2008

rewmer said:
If you have 10 mins a bit of wire and a multimeter you can check what the sensors are doing. Find the black wire from each sensor and attach a length of wire long enough to reach the cabin. Then using the multimeter between each wire and a suitable earth ( I use the ciggarette lighter socket ) you can monitor the outputs individually. Under normal driving they should cycle between 0v and .8 every second or so - it helps to see this if your meter has a bar graph on it - under heavy acceleration they should go to .8v (rich) and stay there whilest you are giving it some and on the overrun go down to 0v (lean). You say they are only two years old - where they genuine parts or patterns ?

Which is fine except that his sensors are 5-0v Titanias,so 0V is rich - 5v is lean.This is why I asked if they output 5v with the ign on but the engine stopped,if they dont then there is a problem,either with the sensors or the car,OR with the diagnostic kit.

rewmer · Nov 10, 2008

My bad ! appologies, thought for some reason we where dealing with a latter one. Storm please ignore any advice I have tendered.

storm · Nov 11, 2008

rewmer said:
My bad ! appologies, thought for some reason we where dealing with a latter one. Storm please ignore any advice I have tendered.

Thanx for trying, just to confirm its a 1995 P38 4.0SE Auto

John L · Nov 11, 2008

right im new but need to start somewhere

not long got a 4.4 HSE (lpg converted)

the engine management light has come on the dash, took it to a garage to plug the comp in to diagnose...

Misfire fault...?
emissions fault...? imagine this is the lambda sensor?

any ideas what i should...? dont fancy a heavy bill right now

p.s. vehicle runs perfect, doesnt feel like its misfiring, no sluggishness etc

puzzled.com/for_sure!!!

Lamdas - P38

storm

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bill_gj

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eightinavee

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storm

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storm

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rewmer

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eightinavee

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rewmer

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storm

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John L

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