GM Tech Milage ???'s
10-12-2010, 02:01 PM
#11
Registered
Never a pretty job.
10-12-2010, 07:44 PM
#12
Registered
I broke 3 of the bolts on a friends 5.4 super duty last time I did one ended up welding nuts on the broken off studs to get them out . How long have they been running ethenol fuel where you live the e10 will make a big difference in your mileage my 496 went down 2 miles to the gallon and it wasn't good to begin with
10-12-2010, 08:47 PM
#13
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Thread Starter
iTrader: (4)
Sorry had to. One of my best friends had an HD 496, while pulling a trailer it was more cost effective to drive my truck and throw $1 out the window every 5 miles than drive his truck.
10-13-2010, 08:56 AM
#14
Charter Member
Wally, normal operating voltage of a standard O2 sensor is .2 (lean) to .9 (rich) volts dc with a mean average of .45 being the result of a 14.7 to 1 air / fuel ratio.
.45Vdc is actually the target the PCM shoots for in its fueling calculations. The reason the voltage varies is because the PCM just isn't that good of a guesser so it over fules, sees the reaction from the sensor and then under fuels and watches and then over fuels ad infinitum.
O2 sensors rarely degrade at the same rate. Using a digital scope with two channels, its easy to see exactly how two sensors compare to each other. Yes, they will get "lazy" over time BUT, in my experience of fixing this stuff for near 30 yrs now, I can tell you the number one fail is actually the internal heater in the sensor that quits long before the actual sensor fails.
Arbitrarily replacing them in pairs without scoping them in full operation first is a lazy way of doing diagnostic work. Usually found happening in the dealership because the techs get paid squat to do diag work and make better coin just swapping out both sensors quickly.
Most newer vehicles use lean air/fuel sensors and at several hundy a pop, just tossing in a few gets mighty spendy real quick.
Old saying, TEST, then replace as needed.
.45Vdc is actually the target the PCM shoots for in its fueling calculations. The reason the voltage varies is because the PCM just isn't that good of a guesser so it over fules, sees the reaction from the sensor and then under fuels and watches and then over fuels ad infinitum.
O2 sensors rarely degrade at the same rate. Using a digital scope with two channels, its easy to see exactly how two sensors compare to each other. Yes, they will get "lazy" over time BUT, in my experience of fixing this stuff for near 30 yrs now, I can tell you the number one fail is actually the internal heater in the sensor that quits long before the actual sensor fails.
Arbitrarily replacing them in pairs without scoping them in full operation first is a lazy way of doing diagnostic work. Usually found happening in the dealership because the techs get paid squat to do diag work and make better coin just swapping out both sensors quickly.
Most newer vehicles use lean air/fuel sensors and at several hundy a pop, just tossing in a few gets mighty spendy real quick.
Old saying, TEST, then replace as needed.
From owning a truck with high mileage (200k+) when i have something fail on my truck thats electrical and theres two of them i do both cause most times the other is close behind due to age and use...
__________________
-Wally
Money can't buy happiness, but it can buy horsepower. And I've never seen a sad person hauling a$$!
-Wally
Money can't buy happiness, but it can buy horsepower. And I've never seen a sad person hauling a$$!
