aintno6

I just got a lt1 scanmaster for my car, and I have been playing around with it, and I'm getting basic info on the way this puppy runs.

Here is my question. How accurate is a healthy gm heated o2 sensor compared to a wideband o2. Basicly, the reading I get from my scanmaster at WOT, how accurate would you say those are? Are they most likely lower or higher?

Just wondering. Because before my tune and delteq install I pulled around 12.5:1 a/f at the dyno day. And now doing a few small wot runs on with the tune and delteq, it looks like im running healthy at a 14:1 a/f. I know I need to go back to the dyno to be sure. But I wanted to get some input on how accurate these stock o2 sensors are.

Thanks,
Mike

OBE1 95Z28

Stock O2 are narrow band, meaning that they are only accurate in a very narrow range centered around 14.7 afr. You should not use these to tune your car!

aintno6

I realize that, but I wondering how accurate they are.

Mike

Injuneer

The problem is that the OEM narrow band sensors have a very flat curve of mV vs A/F ratio. As a result, it takes a very large change in A/F ratio to make a very small change in mV's, when you are up around 12.5 - 13.5:1. And, the mV output at these A/F ratio levels is very sensitive to operating temperature. Hence a small change in operating temperature can produce a large change in mV's, masking the change produced by the true A/F ratio change.

I'm a little surprised that you are finding the car runs at peak performance at 14:1.... most people find the best results in the range of 12.8-13.2:1, with maybe a few people running up to 13.4:1. How did you use the ScanMaster readings to determine you are "running healthy at a 14:1 a/f."?

aintno6

Looks like I'm going to have to get her on the dyno soon. I figured I should to see how much I have gained with the tune and delteq.

Fred the reason why I say its running healthy is because before the tune the best I could turn was 13.8@101 with all the bolt-on's I had. Plus the car had poor gas milage, and was running pretty rich. I was told several local lt1 folks, that with the a/f I was pulling, it was pretty simple to see that the car was in need of tune, and was running rich. Since the tune and delteq I have dropped m y et by .4ths and gained 3mph in the 1/4. The runs much better. And looking at the scanmaster readings on some short WOT runs, I'm not getting any knock, and evry thing seems normal.

I was basing the a/f readings to MV readings of sites info like on here http://www.speedshop.org/store/scrip...p?idproduct=15

Thanks,
Mike