AFR meter/Lambda sensor strange readings
22 June 2002, 09:23 AM
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I'm having a bit of trouble getting my Dawes AFM working correctly. At present i'm getting no LED's lit. All connections have been double checked, with different ground sources checked for pd, and none found.
When i disconnect the lambda sensor and measure the signal wire potential to ground, I get a pd of +0.3V above ground. This seems a tad odd, especially with no sensor connected. When the ignition is switched on to start lambda sensor heating, this voltage decreases slowly until around -0.4V below ground (with sensor connected). With the engine on and up to running temperature, idle seesm to hold around +0.3V. When the throttle is pressed, this voltage fluctuates quite wildely to around -0.6V. Under WOT no LED's are lit, due to these strange voltages.
It is assumed that the voltage on the signal wire should stay positive wrt ground, and climb as the a/f ratio richens.
Can anybody shed any light on the subject (MY97 UK)?
Thanks in advance,
Leeroy
When i disconnect the lambda sensor and measure the signal wire potential to ground, I get a pd of +0.3V above ground. This seems a tad odd, especially with no sensor connected. When the ignition is switched on to start lambda sensor heating, this voltage decreases slowly until around -0.4V below ground (with sensor connected). With the engine on and up to running temperature, idle seesm to hold around +0.3V. When the throttle is pressed, this voltage fluctuates quite wildely to around -0.6V. Under WOT no LED's are lit, due to these strange voltages.
It is assumed that the voltage on the signal wire should stay positive wrt ground, and climb as the a/f ratio richens.
Can anybody shed any light on the subject (MY97 UK)?
Thanks in advance,
Leeroy
22 June 2002, 09:38 AM
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Just been out for another test run, without the AFR connected. Still found the maximum signal voltage under WOT to be around +0.3V, with fluctuations down to -0.7V when the throttle is lifted slightly. At idle, each blip of the throttle results in the voltage dropping to -0.7V momentarily before returning to around +0.2-3V. Does this mean my ECU is being fed duff information from the lambda, and hence my mixture could be excessively lean/rich?
I suppose the sensor may well be on its last legs, i seem to remember Halfords stocking them, is this correct?
Cheers
I suppose the sensor may well be on its last legs, i seem to remember Halfords stocking them, is this correct?
Cheers
23 June 2002, 01:02 AM
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leeroy,
that does sound a bit odd. My vltage readings on wot is > 0.9v. I have heard dodgy things about the halfords type lamda sensors, in so much as not lasting. You may be better off getting an oem one.
Cheers
Paul
also read http://www.scoobynet.co.uk/bbs/threa...threadid=73947 for extra info
that does sound a bit odd. My vltage readings on wot is > 0.9v. I have heard dodgy things about the halfords type lamda sensors, in so much as not lasting. You may be better off getting an oem one.
Cheers
Paul
also read http://www.scoobynet.co.uk/bbs/threa...threadid=73947 for extra info
23 June 2002, 09:20 AM
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Paul, they're the sort of readings I was expecting. I would doubt the sensor if it wasn't for the +0.3V present on the signal wire to ground without the sensor connected.
I'm still puzzled!
I'm still puzzled!
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