I installed a wideband the other day (in my cat-delete pipe) and I think it might be acting strange.

At idle I get a good 14.7, it bounces just a little bit (somewhere around 14.3 to 15.1)

It however goes right to 10.0 when I go wide open (with boost), now I know the car is supposed to run like 9.5:1 stock, but I was tuned by Chris at AMS and its supposed to be at 11.5.

It also seems to be really jumpy. Like sometimes just under minor acceleration with no boost I hit values in the 11 range.

When I installed the latest round of gauges I had the battery disconnected for a period of about 10 hours (overnight) - you can't "lose your tune" by disconnecting the battery for long periods of time can you?

It is a bosch lsu 4.2 sensor, and I think this one cannot read any lower than 10, or any higher than 20 (according to the instructions) so even if I was richer than 10, it would still show 10 I'm assuming.

 

here is a pic of my install....

 

let me also add that I was tuned on 6/19 at ams, and i didnt have this wideband in there yet, they used the "sniffer up the tail pipe" method. They said I was 11.5

 

This morning it was really finicky.. I can't believe no-one has seen something like this.

 

I would log your wideband with EvoScan to see what it is actually reading.

 

it might be a grounding problem with your wideband

 

I don't have any capability to log anything (yet)

I can however keep my eyeballs on the gauge and clearly read what I am telling you guys.

 

Well I read my wideband when doing a WOT throttle run and what I see in an EvoScan log is ALOT more accurate.

 

The wierdest thing is that I think it is reading much richer than it should be. I don't think the car is running this rich.

If you go wide-open throttle you should see it bounce around the target of 11.5 that AMS tuned me for (I would assume)

I get a solid 10.0, which is the lowest amount that my wideband can even measure, which makes me think the sensor might be actually reading lower than 10 but it wont show any lower because 10.0 is the "floor" (20.0) is the "cieling".

Then after I get off the highway today it jumps around to 11 then to 17 then back to 10 when I'm just barely on the throttle.

I don't think the car is actually running these AFR's. Wouldnt I be able to feel something wrong if it was doing this?

 

That sounds like either a grounding problem or the sensor is starting to die. It shouldn't be that inconsistent.

 

I'd do a boost leak test, just to be sure. a small leak anywhere after the turbo will result in rich readings under boost. if the offending hose only comes loose under some conditions...

 

I didn't think of that, but that is a good point. I would think for it to read as rich as it's doing at WOT, that the leak would have to be quite significant and noticeable.

 

Adding a wideband gauge is the first step toward automotive hypochondria

I'm not a fan of tailpipe sniffers. Every exhaust leak, not to mention the cat if you have one, will contribute to lean readings -- which will result in a rich tune. Last time I was on a dyno with a tailpipe sniffer, the AFRs read 0.5 leaner than they do when using a wideband bung up at the downpipe.

 

It was sniffed without a cat - the only mods I have since my tune are:

Oil temp gauge
voltage gauge
wideband (this is how I am seeing this "problem")

 

It is a brand new gauge and sensor, just installed 1 week ago...