How much does a "dead" O2 sensor hurt when racing?

[ez at nova]

I'm curious how much, and how, a toasted 02 sensor affects the car when racing. I'm asking for 2 reasons. First, last time I raced my second pass fried my sensor (scanmaster readings bouncing from 008 to 900 at full throttle), however, I still did get my best run (and last) of 12.2 @112. I'm wondering, if the bad sensor did hurt me, what time I might have achieved. Second, I have no desire to fry my new sensor next time I go, so I was thinking of putting the old toasted sensor back in when I put in race gas (I guess 110 or 114 octane). How detrimental is this?

Thanks,
Jeff

 

[buickboy]

My experience is it will kill your launch 60 ft and ET and we all know how important that is with these cars. My car has laid down as much as .4 with a bad o2.
Mitch

 

[BLACK6PACK]

It shouldn't affect your WOT since I think the chip ignores the 02 at wot. As buick boy said though, it may hurt your launch. How are you going to tune? Just keep turning the boost up and watch for knock? You can get 02s at ramchargers 3 for $66. Or you can buy an open loop chip and forget all about the 02 sensor.

 

[ez at nova]

Well, I'm happy with my JC chips, so I'd rather not get a whole new one for open loop. As far as tuning...yeah you're right it would kind of be hard, but I have only ever tuned for knock anyway. Ever since my car was set up after all my parts went on, I've never touched my FP regulator. It's around 42lbs at idle, and my O2s are around 800-815 on the street, and (when the )2 was working) around 780-790 at 21 lbs of boost at the track. So, I guess I was assuming I still wouldn't touch that and just give it more boost until I'm at my limit. Who knows what that is though. That 12.2 run was made at 21 lbs of boost on 104 octane (I thought I would not fry my O2 using that, HA!) and I ran out of time for the night. I'm sure I can get a bunch more lbs of boost if I'm using the highest octane and have more time to fool with it. I'm thinking probably around 25...

 

[TurboDave]

Yes it can hurt/help. Even at WOT, even though it's ignored. Reason:

It depends on what the dieing O2 sensor did to your BLM cells. During P/E or WOT runs the BLM cells are used in conjunction with the MAF to control fueling (for the most part).
So, cell 15 could be whacked way too high or way too low. Depends, and it will push your fueling too high or too low, depending.

 

[azgn]

your car runs in open loop at WOT so the 02 is not referenced...if you launch at WOT, no problem......the car could run badly until WOT tho.....you can "learn in" a chip with a good 02 and replace it with a bad one at the track and do just fine....just don't reset the ecm