O2 sensor and leaded fuel?


Jul 7, 2001
Has anyone had the Speed-Pro O2 sensor go bad from running race gas? The guy I bought the car from says he never ran anything higher than 100 unleaded for fear of ruining the O2. A friend of mine uses some of my Monte Carlo's 114 in his car while at the track and has a heated O2 with the factory ECM and is constantly going through O2 sensors. I just wondered what you guys have found as I don't really personally know anyone else running the Speed-Pro system. Thanks Jason
We have had O2 sensors come back that are fouled out and no longer work, but never from lead. It's almost always oil or just blackened from being way too rich. Lance and I have never run anything other than leaded race fuel in our cars and haven't had a single problem. If your tuneup is good and you aren't blowing oil through the exhaust, I wouldn't worry about leaded fuel.

Thanks Craig this friday I'm going to run the car for the first time since I bought it 3 weeks ago and I think she will be drinking the good stuff after a few practice runs. HERE COMES THE TIMING AND BOOST! Probably should steal the drag radials off the monte carlo.
I don't trust it. My results arent very reliable. I monitor
4 cylinders with EGT's and they read 1250 ish while the
Wide band reads 9.5 to 10.1. The plug readings are jiving with
the EGT readings. I don't believe that my car would run clean
if the A/F was as rich as it is showing.

I run VP C16 gas exclusively, and run my car in open loop and
just use the wide band in datalogging. My car also noticed
a significant improvement at idle when switching to open loop.
I'm thinking using open headers with the 02 sensor about 4" from
the end is affecting the calibration. Not sure if the lead is the problem.

I use 4 different calibrations that have the VE tables modified
for Different Density altitudes.
If you are running the O2 in a big open collector and have ANY cam in it at all, idling in closed loop will cause problems. Reversion in the collector generally makes the O2 sensor read an a/f ratio of 15.94, which is the leanest reading the system will display. In closed loop the O2 will add fuel in an attempt to correct this reading and it results in a very rich idle.

If the Wideband O2 goes bad. Is this something I can get at my local parts place or do I have to order it from FAST?
Each wideband sensor has a unique calibration. You will need to contact a FAST dealer for a replacement which will come with an upgrade disk containg a new calibration curve to be loaded into your ECU.