I just installed my SM-AFR this weekend and can't seem to get an accurate reading out of it. It does seem quite close, but jumps around varying about 1 point when the sensor warms up. I didn't put any capacitor in when I installed it because from what I can find the V2 doesn't need it, but if it clears up any "noise" it just might fix this problem. The other issue that I am guessing could be the culprit is when I pulled out my old 02 sensor it was stripped out, so I bought a tap and fixed the threads. I figure it could be possible that there is a bit of an exhaust leak around the new sensor since the threads were screwed up. Any ideas?

Here is the video.

PLX wideband jumping around. - YouTube

 

I don't have any experience with the plx, but if its anything like the LC1 proper grounding is crucial to accurate readings. So before anything I would check your grounds. Some people go as far as running a good size ground wire (10-12gauge) to an engine ground or straight to the battery ground.

 

With the PLX only one ground is needed and it is grounded to the chassis ground by my battery. I can ground it to the battery with very little effort, just to see if that helps.

 

looks normal to be? its not going to read a straight flat number. the computer is going to be adding fuel, timing, and air and also subtracting it when needed so its a constant mix match. it will be more solid at wot i know mine jumps about like yours tho maybe i need to look into the grounding part? but from what ive understood it will jump alittle?

 

Looks normal to me.

 

Just moved the ground and its the same. Honestly I'm not sure if something is wrong with my gauge or if my tune could be a little whacky. I sat and watched it for a bit and it seems to jump between 14.3-14.8 constantly, then once every 20-30 seconds it will lean up to 15.3 or so for a second. This is at idle, haven't gotten my hp tuners in yet so I can data log everything.

 

Okay, thanks guys. I didn't realize that this is normal, seems like every video I can find is of people having problems, nobody posts/videos when things work right!

 

honestly that is what mine does? i took a log and sent it off to nelsons and he was able to use it? maybe mines wack too but its the same?

 

it's fine.

 

Isn't the fluctuation around 14.7 the O2 sensors switching and the ECM responding by making the AFR rich then lean? Mine does it too. The O2 sensors are sort-of a discrete input to the ECM where it is either rich or lean and the ECM adjusts the afr to compensate. Too bad they don't use a wideband and let the wideband provide precise AFR feedback.