Hey guys, new to the forums (joined to figure out this issue actually):

My 'Sol came with an XTune A/F guage that worked fine when I got the car; meaning the guage bounced depending on throttle position using one, maybe two lights. Not too long ago I started noticing that multiple lights on the guage would light up at once. For example, My guage will light up all of lean and half of optimal at idle. This worries me for 2 reasons:

1. It now spends a lot of time at lean when I'm giving it 1/4 throttle or less.

2. Despite the guage reading lean, I have noticed a drop in gas mileage, roughly 6-10 mpg. (This could be nothing but a combined factor of it being 20-40 degrees colder, new tires (skinnier, so it shouldn't hurt MPG at least), having car raised .5'', and the fact that the timing may be advanced/retarded more than it was before (From fixing a no start issue). All of this being different from last I drove it regularly).

So my question is this, from those who may have had a similar problem, does it sound more like a failing guage, or a fuel / spark / sensor problem?

P.S. It seems to run fine otherwise, haven't had a chance to check the plugs for a lean condition yet, but I will when my unit get's out of the field.

Thanks for the input,
Greg

 

Narrow band sensors respond in a 0 to 1 volt range, and this is a very small signal to work with. How is the sensor wired? Are your connections solid and free from corrosion?

At part throttle the sensor should be at its most active, bouncing from around 0 to 1 volt and cycling back. If this is the case, either the O2 has failed biased lean, or there is too much air passing over the sensor head.

This can mean:

Air leak
Exhaust leak
Defective O2 sensor
Fuel delivery problem
Coolant sensor problem
TPS mis-adjusted
A bit of a stretch, but ignition timing and cam/crank timing

What was the last thing done to the car before this started happening?

 

There was nothing done. It was sort of a spontaneous thing. I'll check the connections when I'm home and see, besides a possible loose connection I don't see that being an issue.