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

 

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

 

Can anyone help me out?

 

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

 

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!

 

ttt

 

Leeroy just read on an old post of AFM, halfords sensor £50. Don't know if this is right but thought it might help.

Marc

 

Oh yeah, I'm about to fit mine tonight, next hour or so same MY so will post later. All going well.

Marc

 

Just put BTTT on drivetrain on lamda (spelling) might be of use.
Marc