Going the wrong way

[jere]

Originally Posted by Old Mechanic

On the other hand while riding a Cab in Baltimore when Pop was having some surgery done at Johns Hopkins, I noticed that every single Cab had a CEL and ABS warning lights on and the drivers just seemed to ignore them.

regards
Mech

I know with my cab company the drivers pull the fuses most of the time so as not to run up the mileage. When the odometer fuse gets pulled it trips the cel light.

To SentraSE-R did you change the brand of tires or could they be another gen of the same tire with more weight different compound? If your O2 was bad in a Sentra your MPG would be a lot worse I would think.

[SentraSE-R]

The car is a 2006 Scion xB. I did a major seasonal tire swap from P195-65/R15s (OEM are P185-60/R15) to P205-50/R17. I've run the same size 17" tires before, but the old ones were Goodyear NCT-5 (V)s, run-flats that weighed 26 lbs each. The new ones are Cooper Zeon RS3-A all seasons weighing ~22 lbs each.

[jere]

Wow those run flats are some heifers, I bet it helped getting rid of those.

Have you compensated for the difference in tire height? The different height will throw the speedo off a good amount. Taller wheels will make the miles read less, shorter wheel will show more miles.

[SentraSE-R]

Yes, I calibrated my UG against my GPS. When the odometer shows 100 miles traveled, I've actually traveled 109.9 miles - a significant difference.

The OEM tires/wheels weighed 36 lbs each: 17 for the steelies, and 19 for the tires. The run-flats weighed 48 lbs: 22 for the wheels, and 26 for the tires. I haven't put the new wheels/tires on the scale, but they should weigh in @ 44 lbs for the combo.

[jere]

The wheel and tire package seems good from what I know, but if that is the only thing you have changed recently I would still be leery of some unknown effect going on. Maybe from tire patterns or rubber compounds, or maybe side wall stiffness.

Otherwise if you haven't already check your brakes for dragging, and wheels bearings (with heavy wheel/tire packages wheel bearings don't seem to last as long), tire rods, ball joints for any play. They are all pretty easy to check for if you have a jack. Did the old tires have any strange wear that would be an indicator also.

[AndrzejM]

Brake drag, intake manifold leak, clogged EGR - those are the points I would suggest to check.

[SentraSE-R]

Alignment was way off, so I had that done when I replaced the tires.

I'll check the EGR tomorrow. Thanks for the suggestions.

[rmay635703]

Since every vehicle I own now has brake drag, I opt for that.

My cobalt of all the weird things drags less if I high pressure power wash and wax the brake area thoroughly, no idea why this works, I am wondering if I am getting crud and rust off.

My insight I managed to reduce brake drag by installing brake friction reduction springs from napa, they don't fit quite right but have improved though not eliminated my irritating brake drag problems. (at least I don't need to drive to the floor to go 55mph in 3rd gear any time it rains and gets cold)

Cheers
Ryan

[jere]

For brake drag generally all you have to do is just pick up some brake caliper grease, and wire brush and lube the two slide pins. You can usually go for a drive and when you stop put your hand on the calipers and feel if one is hotter than the next. The hot one is the culprit. It is still a good idea to lube the slide pins frequently anyways as general maintenance, and it's pretty easy to do for the novice DIYer

Unless they are rusted stuck or the no one has changed the brake fluid in ages, and rusted the caliper pistons. That takes years of neglect so don't worry about that too much with the xb

[SentraSE-R]

Originally Posted by toc

The voltage is 'at the time of the read'- ODBII is 10400bps.
I'm not sure you'll see the voltage cycle like it should over ODBII.

It continuously goes up to 0.8, and down to 0.2, repeatedly whilst you maintain cruise (i.e. 1800RPM or more, steady throttle, closed loop operation).
At idle, my sensor stays at 0.8 and slows back to 0.2, and cycles slowly (due to volume - idle RPM is low volume).

That'll tell you the O2 sensor is working OK!
The other thing to think of is you'll get a code again if the O2 sensor is useless.
Vacuum style leaks produce O2 sensor codes (air after the AF sensor).

My O2 sensor Bank 1 1 readings went from .078 to .66 and did cycle repeatedly between those values.