AFR guage...funny readings

[Lawbags]

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

[Lawbags]

Ah. Marvelous! I'll try that today

[Lawbags]

???
I'd have thought the title and 'I bought a second hand gauge and sensor' would have indicated such, but clearly not.

But to clarify, yes, it's a wideband gauge AND sensor

[Lawbags]

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?

Edited by Lawbags on Sunday 8th September 10:24

Edited by Lawbags on Sunday 8th September 10:26

[Lawbags]

Potentially the gauge/sensor that's faulty?

[Lawbags]

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?

[Lawbags]

Ah yeah....good call.

I'm just North of Gatwick.

[Lawbags]

Ah bugger. Cheers anyway.

Mind you, I took it out today and gave it a good clean. Re-fitted and it seems to be working ok now.
It's still quite jumpy on idle- between 12.9 and 15.3. It has a race spec cam fitted so I'm guessing that could be because of that?

[Lawbags]

It just goes off the top of the scale which only goes up to 17.