I installed my PLX wideband tonight and did a few pulls and my gauge doesn't seem right. I have an STS kit and mounted the sensor about six inches after the turbo. I did have to extend the wires about six feet to reach the back but I used the same gauge wire and made sure that the connections were soldered good. The gauge reads 14.6-14.9 while at idle and cruising but it reads 12.5-13.1 at WOT. My truck was tuned at a very reputable shop about four months ago and my a/f was a steady 11.5 on their dyno. Any ideas?

 

go back to your tuner and have them plug in and check it.
if they read the same, then your gauge is right.

since they will already be hooked up, get them to look the tune over.

 

My PLX is right on with the dyno. They were withen .01 of each other. You better get it checked to be safe. Weather along with other things can mess with your AFR.

 

Do you still have cats? If so maybe thats why your getting a differnt reading. Move the wb sensor pre cats.

 

The weather last night was almost identicle to when I had my tune done. The only thing that I have changed since my tune was putting in efans. Could that have messed up my af that bad?

 

I do still have cats but I was told to put the sensor after the turbo with the STS kit. The dyno uses a probe in the exhaust tip so wouldn't that be about the sam as where I have the sensor?

 

If thats where the sensor was at when it was dynotuned then I would assume the readings would be the same. I think it needs to be installed before the cats to get an accurate afr.

 

Here are some new details. I checked my tune and my PE was set to .88 which is 12.9afr. This is where it was set on the dyno when the dyno showed 11.8afr. My plx gauge was showing around 12.9 so I changed my PE to .81 which is 11.9afr and did some more logging. With my PE changed my commanded AFR was 11.9 and my gauge started at 11.5 and went 11.9 on the top end of the pull. This leads me to believe that the dyno's A/F gauge may have been wrong. I was not seeing any knock with either setting but I am going to leave it at the richer setting until I can get it back on a dyno to have it checked. If the PLX is correct than my tuner must have nailed my VE settings since I am almost always running the commanded AF according to the gauge.