warm up procedure
#32
02-24-2014 | 08:07 PM
Professional
Joined: Jun 2007
Posts: 235
Likes: 0
From: Fond Du Lac, WI
Yes and no. Truck has to meet conditions to be in closed loop mode. Conditions include run time, coolant temperature and tps % less than 85.
Derived from the service manual-
When engine has reached operating temperature,
the PCM will begin monitoring O2S sensor
input. The system will then leave the warm-up mode
and go into closed loop operation.
My observations- When the engine is started from "cold" or whatever the PCM considers cold it will NOT go into closed loop for at least 200 seconds or 120 degrees whichever comes last. It will use more than twice the fuel it normally does in closed loop mode during this time if you drive it, do the math on that...
A tune could eliminate cat warm up mode (thats what it really is and thats what GM calls it) but if you drive it your going to use way more fuel than you would if you just waited for it to enter closed loop mode. By driving it immediately IF you have a cat you will load it up with hydrocarbons and shorten it's life too...a 200+ dollar expense.
As an example...my daily drive is 39 miles one way. In December I got in and took off every day...figure out the average temp if you like for where I live. I averaged 209 miles per 20 gallons (10.45mpg) the entire month with zero warm up, get in, start it, put my seat belt on, flip the lights on, and go...even scraped the windshield before starting.
By January I had remote start with a temp readout on the fob (I got it for xmas) and I started testing just how much fuel I used if I let it warm up at various temperatures. A few times I let it get all the way to 170 but most of the time I left when it hit 120, you could hear it idle down when it hit 120 and since I have no cat, the fuel smell was gone by then too. So since then I wait til the readout says about 115 before I put my boots on and go outside to scrap the truck off and go to work. My average since then has been 221 miles to 20 gallons or roughly 11mpg. Something to chew on guys.
My testing is with the scangauge II and the old pen and paper method together. My daily trip is like this- Leave house, truck avgs 50-55mph until 4 miles away I get to the freeway then I do 70 until I get to work, where for the last 3/4 mile I avg 35mph right into my parking lot. When it's time to go home the truck is remote started the minute I start taking off my coveralls. Like clockwork it's about 120 degrees again when I step outside. I do not use it for lunch ever so it sits for ten or 11 hours every day. My drive is 39x2 6 days a week. I get gas from the same place every 3 days, never changes. That's about as accurate as I can get, use the data how you will.
Derived from the service manual-
When engine has reached operating temperature,
the PCM will begin monitoring O2S sensor
input. The system will then leave the warm-up mode
and go into closed loop operation.
My observations- When the engine is started from "cold" or whatever the PCM considers cold it will NOT go into closed loop for at least 200 seconds or 120 degrees whichever comes last. It will use more than twice the fuel it normally does in closed loop mode during this time if you drive it, do the math on that...
A tune could eliminate cat warm up mode (thats what it really is and thats what GM calls it) but if you drive it your going to use way more fuel than you would if you just waited for it to enter closed loop mode. By driving it immediately IF you have a cat you will load it up with hydrocarbons and shorten it's life too...a 200+ dollar expense.
As an example...my daily drive is 39 miles one way. In December I got in and took off every day...figure out the average temp if you like for where I live. I averaged 209 miles per 20 gallons (10.45mpg) the entire month with zero warm up, get in, start it, put my seat belt on, flip the lights on, and go...even scraped the windshield before starting.
By January I had remote start with a temp readout on the fob (I got it for xmas) and I started testing just how much fuel I used if I let it warm up at various temperatures. A few times I let it get all the way to 170 but most of the time I left when it hit 120, you could hear it idle down when it hit 120 and since I have no cat, the fuel smell was gone by then too. So since then I wait til the readout says about 115 before I put my boots on and go outside to scrap the truck off and go to work. My average since then has been 221 miles to 20 gallons or roughly 11mpg. Something to chew on guys.
My testing is with the scangauge II and the old pen and paper method together. My daily trip is like this- Leave house, truck avgs 50-55mph until 4 miles away I get to the freeway then I do 70 until I get to work, where for the last 3/4 mile I avg 35mph right into my parking lot. When it's time to go home the truck is remote started the minute I start taking off my coveralls. Like clockwork it's about 120 degrees again when I step outside. I do not use it for lunch ever so it sits for ten or 11 hours every day. My drive is 39x2 6 days a week. I get gas from the same place every 3 days, never changes. That's about as accurate as I can get, use the data how you will.
