loweredfourpointsix

its a wideband but it goes in the tail pipe not the o2 bung.. you think the numbers are off on the wideband?

1999 GT

yea then that might be why...is it possible that the change in exhaust temp could affect the a/f reading? someone correct me if im wrong

PaintballFreak

Yes that is definitely the problem. I would not adjust the fuel using the predator without a wideband monitor that goes in the O2 sensor bung. The tailpipe monitors are much less reliable.

loweredfourpointsix

some other guys A/F ratios were on point tho.. could it be that i have cats so its throwing the A/F off cuz the wideband is at the tail pipe?

loweredfourpointsix

oh and when i was stock the A/F was on point

PaintballFreak

Cats vs. no cats won't necessarily "throw it off" but it could be affected. Mainly if your car thinks you have cats and you don't but anyway, I don't think that is the problem. I think one reason the tailpipe probes don't work as well is due to changes in the pipe diameter cause the reading to be inaccurate. Putting the probe in a bung, closer to the exhaust flange will be more accurate always.


Assuming you know what it is supposed to be around on a stock car, if it's close to that and now you're seeing WAY lean values compared to what it should be, I agree with you that something weird is going on. I really would try to get a bung probe so you know you have the correct AFR before you start messing with fuel on your tuner.

PM cliffyk about it and see what he thinks.

EDIT: I just saw in your other thread that you have the stock catback. I REALLY think the tailpipe probe is the problem regardless of what it told you from your baseline and other pulls.

loweredfourpointsix

between 13.5:1- and 14.5:1 should be around right from what i hear. lets say the tail pipe reading is right, i would be much safer running it rich then leaving it where its at. the worst that will happen if i richen it too much is that it will be slow and my mpg will go in the toilet. I was told the Diablo Predator is a POS.. they told me to sell it and buy the SCT.. i was told the predator will ony richen it up so much.

lilcrate

I don't think it is anything amazing, and the SCT is probably much better, but my tuner uses both and I have not maxed out mine...

PaintballFreak

You want to be way more rich than 14.x at wide open throttle or else your engine is toast. Personally I would shoot for 13.0-13.2 and nothing more.

The stoichiometric afr of gasoline (when all the air and fuel are burned) is 14.7 which is why your car is tuned for that when you are cruising. Max efficiency.

You're right about it being safer to add fuel than remove it, but personally I wouldn't do either unless I knew 100% what my AFR was.

loweredfourpointsix

thanks for the input guys