AFR guage...funny readings
Discussion
I bought a second hand gauge and sensor and plumbed it in yesterday.
Now one of the wires near the plug was a bit tatty so I replaced the worn section.
When I fired the car up, the gauge reads off the end of the scale. When driving it reads all over the place....10's, 15's , off the scale, and even on downrun it's off the scale.
I have no idea how the sensor picks up readings etc, but could my replacing the short section of wire effect this? Maybe it works on resistance or something????
It's an AEM gauge if it matters.
Cheers
Now one of the wires near the plug was a bit tatty so I replaced the worn section.
When I fired the car up, the gauge reads off the end of the scale. When driving it reads all over the place....10's, 15's , off the scale, and even on downrun it's off the scale.
I have no idea how the sensor picks up readings etc, but could my replacing the short section of wire effect this? Maybe it works on resistance or something????
It's an AEM gauge if it matters.
Cheers
Well that's something at least. However you didn't say whether the car is stock or modified, closed loop or open loop so we're a bit in the dark as to what the readings ought to be. Closed loop should be 14.7 most of the time except on full throttle. On the overrun with injector fuel cut off (assuming this happens) it should default to free air or 20.8/20.9.
Open loop with variable fueling could be any reading under the sun depending on how the car's been set up.
Open loop with variable fueling could be any reading under the sun depending on how the car's been set up.
It's closed loop.
With the probe in open air, it reads 14.7 for a few seconds, then flickers between 13 and 15, drops back to 14.7 ish then leaps off the scale (the max is 17 on my gauge)
With the probe back in, it almost mirrors this with the car not running.
On fire up when cold, it'll sit at 14.7 for a few seconds, then drop off the lower scale for a few seconds then shoot off the upper scale.
Sound normal?
With the probe in open air, it reads 14.7 for a few seconds, then flickers between 13 and 15, drops back to 14.7 ish then leaps off the scale (the max is 17 on my gauge)
With the probe back in, it almost mirrors this with the car not running.
On fire up when cold, it'll sit at 14.7 for a few seconds, then drop off the lower scale for a few seconds then shoot off the upper scale.
Sound normal?
Edited by Lawbags on Sunday 8th September 10:24
Edited by Lawbags on Sunday 8th September 10:26
Lawbags said:
It's closed loop.
With the probe in open air, it reads 14.7 for a few seconds, then flickers between 13 and 15, drops back to 14.7 ish then leaps off the scale (the max is 17 on my gauge)
With the probe back in, it almost mirrors this with the car not running.
On fire up when cold, it'll sit at 14.7 for a few seconds, then drop off the lower scale for a few seconds then shoot off the upper scale.
Sound normal?
Not normal in the slightestWith the probe in open air, it reads 14.7 for a few seconds, then flickers between 13 and 15, drops back to 14.7 ish then leaps off the scale (the max is 17 on my gauge)
With the probe back in, it almost mirrors this with the car not running.
On fire up when cold, it'll sit at 14.7 for a few seconds, then drop off the lower scale for a few seconds then shoot off the upper scale.
Sound normal?
Edited by Lawbags on Sunday 8th September 10:24
Edited by Lawbags on Sunday 8th September 10:26
Lawbags said:
Potentially the gauge/sensor that's faulty?
In free air it should sit rock steady at 20.9. If not then the devise or the sensor are FUBAR.The sensor is not very robust so I would suspect that first. Also be aware you should not mount it where it can get condensation on it as the sensor 'ceramic' can crack.
Steve
fatjon said:
is it an innovate LC1?
No it's an AEM and I too would suspect the sensor rather than the controller 1st 
and yes oxygen sensor's don't like being man handled/shocked I have seen these things during fitting into the bung and rattled around the surrounding area like a shaking pensioner wielding a spanner 
not saying that's what's happened here just saying treat your NB/WB sensors with kid gloves 
Lawbags said:
Is there any way to test it properly? It's £70 odd for a new sensor so I'd rather be sure!
And you don't think the bit of new wire could be the issue? I don't know how the probe works, but if it's resistance, it might alter the readings surely?
I don't believe your wire repair is the issue. If you had introduced a resitance then your AFR readings could perhaps be wrong but would stay steady. Best bet is to see if you can borrow a sensor to test with. Where in the UK are you?And you don't think the bit of new wire could be the issue? I don't know how the probe works, but if it's resistance, it might alter the readings surely?
Steve
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