5 mpg now...... wtf!
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Joined: Feb 2004
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From: Northeast PA
Is it coming up to full spec operating temp?
On the scanner make sure its reaching full operating temp (and the the CTS is operating full range accurately) reading ambient before starting and then proper operating temp when warmed up.
If its not coming up to spec temp via either overcooling or the CTS being off and reading too cool it will run fat.
HTH
jimmy p
On the scanner make sure its reaching full operating temp (and the the CTS is operating full range accurately) reading ambient before starting and then proper operating temp when warmed up.
If its not coming up to spec temp via either overcooling or the CTS being off and reading too cool it will run fat.
HTH
jimmy p
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Yeah, the CTS runs about 180-190, and I asked mike at 5 star about this, he said that the computer will go into closed loop at anything over 150, so they are not a stupid as the older map based systems. I guess for emissions reasons, the epa wants the cat and the rest of the system into closed loop as soon as possible.
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Joined: Jun 2008
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From: Wayyy NoCal, USA
O2 sensors are funny critters. Simple in concept, but different brands do seem to perform differently in different vehicles.
My current ROT is to use whatever is coming out unless there was a problem. I've rarely improved performance by changing brands, but I've sure hurt it!
And they can go bad at any time. In general, they last a long time, but sometimes they don't. If you can afford it, try swapping the pre-cat ones (no need to change post cat sensor). If it fixes it, great. If not, you have spares to install. I like to change every 100K as PM and to provide optimal mpg.
My current ROT is to use whatever is coming out unless there was a problem. I've rarely improved performance by changing brands, but I've sure hurt it!
And they can go bad at any time. In general, they last a long time, but sometimes they don't. If you can afford it, try swapping the pre-cat ones (no need to change post cat sensor). If it fixes it, great. If not, you have spares to install. I like to change every 100K as PM and to provide optimal mpg.
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the Banks housing is too small to allow the use of a stock filter, already tried that. Being recently unemployed, I don't want to throw parts at the truck. Anyone know what the numbers should be for fuel trims? I can log hem with the SCT or with the Matco scanner, but don't realy know what numbers to look for
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From: Long Island USA
The trims should be near 0, if everything is exactly like stock. If they are far far off (+ or -), then the PCM is adjusting for some reason.
Over time, if they go back and forth all over the place, something is DEFINITELY awry, and not just low fuel pressure, low MAF function, etc.
Read them and report back, and I'm sure we can get a pro to look at them.
Over time, if they go back and forth all over the place, something is DEFINITELY awry, and not just low fuel pressure, low MAF function, etc.
Read them and report back, and I'm sure we can get a pro to look at them.
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cool, I will log them today. Off the top of my head, I know that they were around 0, none were 0, some were + and some were-, and they were switching back and forth a little. Does the number change any with the tuning from 5 star? I guess I should talk to Mike. Thanks for the help guys, realy appreciate it.
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Joined: Jul 2002
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From: Long Island USA
Long-term fuel trims should be somewhat stable, short term ones jump a bit back and forth. I'd be slightly more interested in the long term ones.
Not sure WHAT happens with the 5-star tunes, but at idle, that's stoich or should be, so that's a good place to start.
Not sure WHAT happens with the 5-star tunes, but at idle, that's stoich or should be, so that's a good place to start.
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At idle, the short term trims are even with each other varying from.95-1.03, switching several times a second up and down. Seem normal to me. The long terms vary, depending on what event is going on. Here is where it gets interesting. When holding the rpm to 1500 in park, the STB2 does the same as iidle, but the range is narrower, STB1 switches just as wide as at idle. LTB2 holds pretty steady around 1.0, while LTB1 drops to .95. There is also a slight miss, and a pop through the exhaust at this rpm. If rpm is increased to 2000, all ST stabilizes closer to 1.0, and all LT stabilizes at 1.0, and missing/popping goes away. When letting engine drop back to idle, ST begins the high range switching, and LTB2 stays at 1.0, but LTB1 drops to .95. Occaisionally there is a miss at idle in gear, but not very often, and there is no detectable miss while driving steady at 1500rpm. I will have to record the logs to drive around and see what happens then, just thought I would throw this cursory info out there to see if someone had an idea of where to go. Obviously something is off.
Thanks guys
Thanks guys
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Joined: Feb 2011
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This Problem sounds almost Exactly like mine. replaced cops and o2 sensor slight stumble and all. Truck runs great. turns out my back tire was low. im running 37's and the rear pressure was 20 psi. went through a whole tank of gas in under 100 miles. Not saying this is your problem but it might help. 
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Good thought, I checked pressure, and they are holding steady at 42/38 f/r respectively. A whole tank in under 100 miles, sound like where I was heading. What sort of mileage do you normally get with the 37's? Also, what gears do you have?
UPDATE, cleaning the maf helped, mpg back up into the 7's!!! Still pathetic, but that is all city driving, and some extended idle time to warm it up, I don't want to put my 9 month old daughter in a 40 degrees truck, so maybe it is not all that bad.......
UPDATE, cleaning the maf helped, mpg back up into the 7's!!! Still pathetic, but that is all city driving, and some extended idle time to warm it up, I don't want to put my 9 month old daughter in a 40 degrees truck, so maybe it is not all that bad.......
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Stock gearing but usually average 13, 14 mpg depending on the additive i use. Right now i'm using lucas and fill up at cheveron, but the best bang for fuel additive is startron. fixes the ethanol problems. comes in a little blue bottle kind of hard to find. With it i got over 300 before the gas light came on but i think the moons were aligned and i had a good tail wind. Also i have no cat. the po thought it was a good idea to take out.
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Joined: Jul 2002
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From: Long Island USA
At idle, the short term trims are even with each other varying from.95-1.03, switching several times a second up and down. Seem normal to me. The long terms vary, depending on what event is going on. Here is where it gets interesting. When holding the rpm to 1500 in park, the STB2 does the same as iidle, but the range is narrower, STB1 switches just as wide as at idle. LTB2 holds pretty steady around 1.0, while LTB1 drops to .95. There is also a slight miss, and a pop through the exhaust at this rpm. If rpm is increased to 2000, all ST stabilizes closer to 1.0, and all LT stabilizes at 1.0, and missing/popping goes away. When letting engine drop back to idle, ST begins the high range switching, and LTB2 stays at 1.0, but LTB1 drops to .95. Occaisionally there is a miss at idle in gear, but not very often, and there is no detectable miss while driving steady at 1500rpm. I will have to record the logs to drive around and see what happens then, just thought I would throw this cursory info out there to see if someone had an idea of where to go. Obviously something is off.
Thanks guys
Thanks guys