One thing I always do is to disconnect the battery for at least 30 minutes, but prefer to leave it disconnected for an hour. This has always worked wonders for me. I do it anytime I do any work on the vehicle that involves the computer (sensor replacements, etc.), or whenever I notice the mpg's start to drop. Works for some, doesn't for others . . .
Quest for Better MPG
- Thread starter Winston
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I go round and round with myself as to whether I should get a car that gets better mpg. However, a couple of repairs to gas saver would quickly offset any gas savings. This truck has been unbelievably reliable, so I am afraid to try anything else. Plus it is worth nearly nothing (maybe $3k). A good used Prius would be $20.
I am surprised TS suggested a K&N! I will try 5W20 oil in this truck, but could never bring myself to install a K&N.
I never thought about the higher pressure in the tires increasing the diameter, but it makes perfect sense.
As far as the plugs, I know now that the Iridiums would last a bit longer than the Platinums (100k vs 60k), but I do not think it would make much difference in performance.
And yes, the air conditioner still works like new. It has never needed any maintenance.
I am surprised TS suggested a K&N! I will try 5W20 oil in this truck, but could never bring myself to install a K&N.
I never thought about the higher pressure in the tires increasing the diameter, but it makes perfect sense.
As far as the plugs, I know now that the Iridiums would last a bit longer than the Platinums (100k vs 60k), but I do not think it would make much difference in performance.
And yes, the air conditioner still works like new. It has never needed any maintenance.
I was too quick to judge the benefits of the O2 sensor replacement. I think it made about a 1-2mpg difference. when I started this thread I only had done one tank with the new sensor. Now I have done a few more tanks and I am definately getting better mpg. I also seem to have better throttle response when the engine is cold. I just used a universal O2 sensor made by Denso. It was about $40 vs the $90 for the OEM type. It was very easy to connect and the wire colors on the sensor matched the wires on my truck. I would definately recommend this piece of preventative maintenance for older vehicles.
The better cold throttle response is probably from the new spark plugs. The engine is in open loop mode when cold and ignores all the data from most of the sensors including the 02 sensor. The 02 sensor has to heat up to about 600 degrees and the coolant temperature be 120-160 degree F. (varies between different cars and car makes) to get into closed loop mode. Once in closed loop mode, the O2 input is only used during idle and cruise conditions, not acceleration or WOT (wide open throttle).
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O2's do get lazy. I imagine that this can alter your long term fuel trims. I don't think it would show much in a straight highway cruise ..but with lots of open loop operation, I believe that it would make a measurable differnence.
The O2 readings in open loop don't alter anything directly ..but they aren't ignored. Too many rich or lean conditions in reaction to the premapped fuel curve (based on MAP) will cause the PCM to alter that fuel curve in corrective action. Either broadening or narrowing the injector pulse width ...or so my FSM states.
The O2 readings in open loop don't alter anything directly ..but they aren't ignored. Too many rich or lean conditions in reaction to the premapped fuel curve (based on MAP) will cause the PCM to alter that fuel curve in corrective action. Either broadening or narrowing the injector pulse width ...or so my FSM states.
Replacing a bad 02 sensor would make a "measurable" difference in open loop mode? How? Quote from seriesoneperformance.com
"2. Open loop - During engine warm-up the fuel mixture control is based on inputs from all sensors except the O2 sensor. The length of time open loop lasts depends on coolant temp., O2 sensor temp. and the open loop timer. Open loop occurs at every start-up.
3. Closed loop - After the timer has expired and the engine and O2 sensor have warmed up, the ECM uses O2 sensor input to fine tune fuel control. The system remains in closed loop until a change in load occurs or the O2 sensor cools off. If a change in load occurs the ECM adjusts fuel delivery accordingly, ignoring the O2 input. The O2 input is only used during idle and cruise conditions.
CLOSED LOOP – during closed loop operation the A/F ratio is constantly swinging from slightly rich to slightly lean and back. The A/F ratio is maintained at an average of 14.7 : 1. This ratio allows for the best catalytic converter operation and the least amount of tailpipe emissions during the following conditions:
A. Idle
B. Steady cruise "
http://www.seriesoneperformance.com/sop/tech/engineperformance.html
This again is going to vary according to make/model. Some vehicles can enter "semi-closed loop"
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I explained that.
How does your engine compensate for fuel system degradation over 100k miles? Clogging injectors and weakening fuel pump?
Now in closed loop ..everything is taken care of ..but what about open loop? Will a premapped fuel curve be correct for 100k with all the aforementioned degradations? Same injector pulse width at the same MAP level ...forever?
Nope. The O2 readings are recorded and that alters the premapped fuel curve. This is in speed/density systems anyway.
Open loop ..unless you're a highway king, can make the 02 sensor the ONLY thing that can make your fuel economy peak.
From that same link:
FUEL INJECTION CONTROL PROGRAMS
The PCM uses two programs to control fuel delivery through the injector.
Both programs' commands are represented by numbers on a scan tool.
0% is the mid-point or normal command. A (-X%) means fuel is being subtracted, a (+X%) means fuel is being added as compared to the normal fuel need.
A. Short-term fuel trim - a short term or "right now" fuel correction based on O2 sensor input. ( GM: Integrator or INT 128)
B. Long-term fuel trim - a long term or learned correction based on the short term command. It has 16 or more different cells for different engine load and speed combinations. Long-term fuel trim is the basic fuel program that can adapt to changes in operating conditions.
First of - who saids there is going to be "fuel system degradation over 100K miles?" I have a 1995 vehicle with close to 200K on it, never had any of the fuel injectors replaced or cleaned. Haven't replaced the fuel pump either. I've always used what is now considered "Top Tier" fuel, and change the fuel filter every 2 years. So I should have major degradation? I bought this vehicle with 15K on it - 1 year old, and it still gets EXACTLY the same mileage it did when it was new(er). The power is also the same. I have drove the same 400 mile trip numerous times over the years (San Diego to Phoenix) The gas mileage has never varied by more than about .5 MPG If there was indeed "degradation" of the fuel system, the MPG would have dropped.
I can agree there may be some fine tuning due to 02 input, but very minor ones, not ones that are going to make most people see major improvements in MPG.
I've replaced several o2 sensors on various vehicles I've owned and never seen any significant change one way or another. There are many other sensors that will have a much greater impact on MPG
Besides,we are going away from the whole point of my post - which was, it's probably not the replaced 02 sensor giving him "better throttle response when the engine is cold" it's most likely the spark plugs. 60K on any plug is a lot. Also an 02 sensor does not even start "working" or I guess the proper term is "switching" until it hits at least 600 degree F. That is somewhere between "warm" engine and "hot", definitely not "COLD" My 2005 Trailblazer has more power in the first 3-4 minutes before the engine hits normal operating temperature as well. On many vehicles you can hear when the o2 sensor starts "switching" by the idle speed and the quality of the idle.
Well I changed the spark plugs over six months ago. So I had time to determine if that helped my throttle response or mpg. I noticed absolutely no improvement. 60k is a long time for spark plugs, but it is the recommended change interval.
The four wire O2 sensors have a heater to bring them up to temp quicker. My guess is that the heater got weak or failed. I think the heater brings the sensor up to temp in a minute or two. I bet the computer uses that reading as soon as the O2 sensor is up to temp. Although I do not know for sure.
The four wire O2 sensors have a heater to bring them up to temp quicker. My guess is that the heater got weak or failed. I think the heater brings the sensor up to temp in a minute or two. I bet the computer uses that reading as soon as the O2 sensor is up to temp. Although I do not know for sure.
You didn't mention when you changed them in your original post.
Yes the heater does bring it up to temp sooner, though I think a minute or two is a little optimistic. Still the temp from the ECT has to be at least 120-160 degrees F - I know that's a wide range, it depends on the car.
Just curious, what oil did you use before changing to the 5W-20?
FWIW, there is a cool chart at this web site, about 3/4 of the way down on the page.
http://fordfuelinjection.com/?p=2
http://fordfuelinjection.com/?p=2
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..and the entire rolling fleet has the exact same results as you? Do they all have your house, wage earnings? Same vehicle? The world is an uncertain place. Detroit, well ..certainly DC, doesn't agree with your assesment of potential problems with certifying an engine/emissions package for 80k ..so they put some added safeguards int he mix ..just in case your mojo isn't present in the general population in enough concentration.
..and the entire rolling fleet has the exact same results as you? Do they all have your house, wage earnings? Same vehicle? The world is an uncertain place. Detroit, well ..certainly DC, doesn't agree with your assesment of potential problems with certifying an engine/emissions package for 80k ..so they put some added safeguards int he mix ..just in case your mojo isn't present in the general population in enough concentration.
You are really funny guy. I guess you fit the old saying, "Don't confuse me with facts my mind is made up"
You are really funny guy. I guess you fit the old saying, "Don't confuse me with facts my mind is made up"
..and the entire rolling fleet has the exact same results as you? Do they all have your house, wage earnings? Same vehicle? The world is an uncertain place. Detroit, well ..certainly DC, doesn't agree with your assesment of potential problems with certifying an engine/emissions package for 80k ..so they put some added safeguards int he mix ..just in case your mojo isn't present in the general population in enough concentration.
BTW, as much fun as it would be to point out ALL the holes in your above statements - I'll refrain. This was supposed to be about helping out a fellow motorist, instead you made it into a rant over semantics. Those of us who have worked in the automotive industry for more than 40 years are always amused by you "know - it -alls" Thanks for giving me a lot to share! LOL
BTW, as much fun as it would be to point out ALL the holes in your above statements - I'll refrain. This was supposed to be about helping out a fellow motorist, instead you made it into a rant over semantics. Those of us who have worked in the automotive industry for more than 40 years are always amused by you "know - it -alls" Thanks for giving me a lot to share! LOL
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I see. Well, don't hold back ..you seem to have a grip here. ..so let it fly. I'll dig into my FSM to quote the section of corrective actions so you can send an edit/error note to DC. They need your input.
Hey oldmaninsc, come back and tell us what long term fuel trim is, how much it can be altered, and what it is altered in response to. Also whether or not it is used in open loop.
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I started using FP60 from www.lubecontrol.com in my wife's Sienna. She went from 19.6 mpg to 20.7 mpg. She's a sales rep and drives 30k miles per year.
I removed the 50 pound spare tire from my Land Cruiser. Main reason was to improve its weak acceleration and help however slightly in braking.
For improved mpg (in non-hybrid vehicles), I think of the brakes in this way:
The more I use the brakes, the more fuel I use.
I removed the 50 pound spare tire from my Land Cruiser. Main reason was to improve its weak acceleration and help however slightly in braking.
For improved mpg (in non-hybrid vehicles), I think of the brakes in this way:
The more I use the brakes, the more fuel I use.
Winston:
Here's a fresh idea that might be worth experimenting with. It's known by some as "Pulse & Glide". I picked this one up while plowing through the mass of Prius info that's all over the internet. It's especially effective in squeezing a few more mpg out of a Prius. It would be interesting to see if it helps with your vehicle.
P&G can't be used everywhere all the time - traffic and safety concerns are paramount, of course. Here's how it works: pick a range of speeds that will work for the road ahead where you will P&G. The range should be 10-15 mph, so for example you could use a window of 30-40 mph, 30-45, etc. If you start from the low number, gently get on the gas and accel to the higher number and a moderate rate. Once you get to the high number, ease off the gas until you hit reach the transition point right between acceleration and deceleration. This is easy in a Prius, since you have an energy flow display, and the arrows on it go neutral as you establish a good glide. Modulate the gas pedal to keep the car at that "neutral point" between accel and decel and let the car gradually glide down to the lower end of your speed range. Our display makes it easy, but you can feel the neutral point easily with a little practice. Repeat the cycle until conditions call for a change. Of course, don't try this in traffic, unless you've got a lane to yourself (or unless you really don't mind irritating the daylights out of the drivers around you...).
If you use P&G when it's appropriate, you'll probably squeeze out a few extra mpg, unless you can't do it often enough (or perhaps if the "barn door" aerodynamics of your Montero sufficiently reduce your proportion of glide time).
Try it, you may be surprised at the result (then again, you might not be...).
Here's a fresh idea that might be worth experimenting with. It's known by some as "Pulse & Glide". I picked this one up while plowing through the mass of Prius info that's all over the internet. It's especially effective in squeezing a few more mpg out of a Prius. It would be interesting to see if it helps with your vehicle.
P&G can't be used everywhere all the time - traffic and safety concerns are paramount, of course. Here's how it works: pick a range of speeds that will work for the road ahead where you will P&G. The range should be 10-15 mph, so for example you could use a window of 30-40 mph, 30-45, etc. If you start from the low number, gently get on the gas and accel to the higher number and a moderate rate. Once you get to the high number, ease off the gas until you hit reach the transition point right between acceleration and deceleration. This is easy in a Prius, since you have an energy flow display, and the arrows on it go neutral as you establish a good glide. Modulate the gas pedal to keep the car at that "neutral point" between accel and decel and let the car gradually glide down to the lower end of your speed range. Our display makes it easy, but you can feel the neutral point easily with a little practice. Repeat the cycle until conditions call for a change. Of course, don't try this in traffic, unless you've got a lane to yourself (or unless you really don't mind irritating the daylights out of the drivers around you...).
If you use P&G when it's appropriate, you'll probably squeeze out a few extra mpg, unless you can't do it often enough (or perhaps if the "barn door" aerodynamics of your Montero sufficiently reduce your proportion of glide time).
Try it, you may be surprised at the result (then again, you might not be...).
On the Prius, is that "neutral point" when the throttle is closed but the regenerative braking has not turned on?
In a regular car, that point would be..with your foot off the gas pedal. (In top gear). The difference is that in a regular car the engine will slow down the car..but the fuel injectors are completely turned off. In a Prius I would expect the engine to be disengaged from the wheels and shut off. You can't do that legally in a regular car...
If the road you're on has traffic lights, consider not doing this--they might be coordinated for traffic operating at the speed limit.
In a regular car, that point would be..with your foot off the gas pedal. (In top gear). The difference is that in a regular car the engine will slow down the car..but the fuel injectors are completely turned off. In a Prius I would expect the engine to be disengaged from the wheels and shut off. You can't do that legally in a regular car...
If the road you're on has traffic lights, consider not doing this--they might be coordinated for traffic operating at the speed limit.
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