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Our Mazda has a total of four oxygen sensors, which Sparkplugs.com carries direct replacements for, providing the sensors with the proper length wiring and harnesses.
Here’s a well used sensor (left) compared to a new sensor from Sparkplugs.com (right).
O2 sensors can be easy to install, like this one here that sits after the cat. However, some sensors can be far up behind the firewall, which requires a contortionist and special-reach wrenches to get to. Each vehicle varies, but transverse engines don’t seem to be the friendliest in this department.
With our MPV's drivetrain quenched with fresh Royal Purple fluids, we were immediately back on MKC’s dyno.
Firing the car up for the first time, it was clearly evident the engine was running smoother. It also seemed like the idle picked up a 100 RPM or so. Blipping the throttle made it even more apparent that this hiccup-eliminating treatment was just what the car needed. We were excited to see the dyno results!
This graph shows the before-and-after horsepower, the red line being with the new fluids and plugs. From start to around 5200 RPM there is a visually apparent “cleaning up” of the graph, that nets between 4-8whp. Up top, however, things remained erratic and we could not get the car to smooth out the power line.
Just by quickly looking at the basline run (blue), one could guess there is either a fuel octane or ignition problem. Sometimes even a wheel imbalance can cause dips, but they’re usually pretty uniform and the spikes are smaller. The fact that we were testing with 93 octane, however, should eliminate the octane variable.
If you look at the peak numbers, we lost 1.7 horsepower. But the average power throughout the runs appears to be up, thanks to a smoother dyno curve in red. On the dyno, the 35-95 MPH pull in third gear also improved by nearly two-tenths of a second (check out our detailed test summary, including average power numbers, on Page 7)!
If it wasn’t for whatever is happening at 6100 RPM, we could have seen a bigger gain. At that point the red graph looks like it wants to give us more, but something is causing it to dip suddenly.
The torque curve on the next page will help explain the gains and losses further..
