Big Diesel, MPG increase ideas?

[ps2fixer]

How does cylinder deactivation get effected by oil change intervals? Does the oil somehow directly get used to control the ignition, like on a power stroke oil pressure is used to inject fuel (HEUI sytem). I figured it's all electronic, but I haven't owned one, only what people say online about them and what friends and family experienced as well as my dad as he was a mechanic.

I've seen some engine's setup on youtube where the exhaust went into another cylinder so the engine was half normal engine and the other half was used to use more of the energy from the initial fuel. I think they might have been adding water or something, it was a long time ago when I saw the video, pretty sure it was on a boxer engine.

My comment about the vibration is just from the idea of a 4 cylinder 3.65L engine would vibrate a lot more than a 1.8L 4cyl. Really the engine vibration would be the same as the v8, just spaced apart per fire, so it would be a lower frequency and in my mind would be felt more. Kind of like the punch of a sub woofer vs a normal woofer speaker,say 20hz vs 120hz. Actually that's kind of an interesting thing to do the math on, 1500rpm *4 (2 rev per fire per cylinder) is 6000 fires per min/ 60 is 100 fires per sec. That should translate the vibration from the engine would be around 100hz for my diesel at fairly typical speeds (55mph).

No engine is vibration free, but some are balanced much better than others. The fact there's effectively a controlled explosion going on inside is kind of impossible to smooth out to silk smooth. Good engine mounts, transmission mounts, rubber isolated drive shaft (like my LS400 has) can help loads of course but the engine itself still has a vibration while running.

It's not the greatest experiment, but back when I drove my corolla, I disconnected 2 of my injectors to turn the 4cyl into a 2 cyl to see what kind of mpg effect it had. Before I got even a mile down the road I thought of a big issue with that, the ECU is expecting all cylinders to be firing, and the disabled cylinders would be pumping normal air into the exhaust which would trigger the computer to dump more fuel to keep the ratios right. It ran rougher and lacked a lot of power but it did drive like that. If I was able to disable the intake valves as well then it would have worked fine I would think.

It's interesting about the deactivated cylinders having less wear, of my understanding a piston isn't the correct shape until it's heated up, and the majority of the wear is caused when the engine is cold, so if the cylinder is only used to pump air, I figured there would be more wear since it would be cold for longer.

Turning a v6 into a 3cyl or a v8 into a 4cyl is a neat concept in my mind. I might have to toy around with that idea some day with a junker yard vehicle some day. I have a ford ranger in the yard that's just a junker. Would be neat to disable half the engine, put a turbo on the other half, and try to get about the same hp out of it as stock, but using less cylinders. I'd assume it would get better mpg overall but kind of hard to say. The cylinder pressures and pistons, rods, and, valves would see more stress, but the crank and beyond should be fine.

Actually, that corolla of mine could be a prime candidate for the half engine size test. It has a valve cover that's really easy to remove and I have a spare engine that's blown up so I have an extra head and such. Could grind off the intake valve lobes for two of the cylinders (DOHC engine), and see how it does MPG wise. It's a high torque 4cyl, peak around 2800rpm so it shouldn't do too bad as a 2 cyl. The smaller version of the engine is peak torque at 5200rpm and I've drove one of them and it seems to be horrible for mpg but it also has a different transmission (3 speed no lock up vs 4 speed + lockup).

Btw, the corolla has nothing special about the oil system, so I changed it every 15k miles with quality synthetic oil. Not sure if 80k miles would be enough to see issues from it, but I haven't noticed anything yet besides the slight power drop. It had a sweet spot where the timing would pull back and mpg was great, a tiny bit more throttle and it would hit 39 advancement and mpg would tank 10% or so. The last 6 months or so I had a very hard time getting it into the sweet spot, that's the only way I knew it had less power (more throttle to go the same speed).

Also it's worth noting that rpm isn't everything when talking about MPG, generally speaking highest gear and going as slow as possible in said gear gives the best MPG, but different vehicles respond differently. My dad's Mazda 1989 (pre ford era) 2.6L 4x4 truck with 4.30 gearing would at best get 20mpg. He always shifted early and drove the truck easy. He hauled a ton of stuff with it and the mpg would drop a little but normally not bad if he wasn't trying to go fast (like over 50mph). When he bought his T100, he car dollyed it through Ohio and half of Michigan in 4th gear doing 3000 rpm and was getting 20mpg with the load. The T100 is physically bigger than his truck and sat much higher plus the dolly pushed it higher, so the frontal area was massive compared to empty. About the only thing we can think of is that engine likes higher rpm and we were driving it wrong for it's engine's wants. It was a DOHC engine and peak torque high up like the 1.6L corolla engine so it seems to relate to peak torque rpms a bit. I've seen other people mention it's related to piston speed (flame travel speed or something like that).

[Tahoe_Hybrid]

Originally Posted by ps2fixer

How does cylinder deactivation get effected by oil change intervals? Does the oil somehow directly get used to control the ignition, like on a power stroke oil pressure is used to inject fuel (HEUI sytem). I figured it's all electronic, but I haven't owned one, only what people say online about them and what friends and family experienced as well as my dad as he was a mechanic.

I've seen some engine's setup on youtube where the exhaust went into another cylinder so the engine was half normal engine and the other half was used to use more of the energy from the initial fuel. I think they might have been adding water or something, it was a long time ago when I saw the video, pretty sure it was on a boxer engine.

My comment about the vibration is just from the idea of a 4 cylinder 3.65L engine would vibrate a lot more than a 1.8L 4cyl. Really the engine vibration would be the same as the v8, just spaced apart per fire, so it would be a lower frequency and in my mind would be felt more. Kind of like the punch of a sub woofer vs a normal woofer speaker,say 20hz vs 120hz. Actually that's kind of an interesting thing to do the math on, 1500rpm *4 (2 rev per fire per cylinder) is 6000 fires per min/ 60 is 100 fires per sec. That should translate the vibration from the engine would be around 100hz for my diesel at fairly typical speeds (55mph).

No engine is vibration free, but some are balanced much better than others. The fact there's effectively a controlled explosion going on inside is kind of impossible to smooth out to silk smooth. Good engine mounts, transmission mounts, rubber isolated drive shaft (like my LS400 has) can help loads of course but the engine itself still has a vibration while running.

It's not the greatest experiment, but back when I drove my corolla, I disconnected 2 of my injectors to turn the 4cyl into a 2 cyl to see what kind of mpg effect it had. Before I got even a mile down the road I thought of a big issue with that, the ECU is expecting all cylinders to be firing, and the disabled cylinders would be pumping normal air into the exhaust which would trigger the computer to dump more fuel to keep the ratios right. It ran rougher and lacked a lot of power but it did drive like that. If I was able to disable the intake valves as well then it would have worked fine I would think.

It's interesting about the deactivated cylinders having less wear, of my understanding a piston isn't the correct shape until it's heated up, and the majority of the wear is caused when the engine is cold, so if the cylinder is only used to pump air, I figured there would be more wear since it would be cold for longer.

Turning a v6 into a 3cyl or a v8 into a 4cyl is a neat concept in my mind. I might have to toy around with that idea some day with a junker yard vehicle some day. I have a ford ranger in the yard that's just a junker. Would be neat to disable half the engine, put a turbo on the other half, and try to get about the same hp out of it as stock, but using less cylinders. I'd assume it would get better mpg overall but kind of hard to say. The cylinder pressures and pistons, rods, and, valves would see more stress, but the crank and beyond should be fine.

Actually, that corolla of mine could be a prime candidate for the half engine size test. It has a valve cover that's really easy to remove and I have a spare engine that's blown up so I have an extra head and such. Could grind off the intake valve lobes for two of the cylinders (DOHC engine), and see how it does MPG wise. It's a high torque 4cyl, peak around 2800rpm so it shouldn't do too bad as a 2 cyl. The smaller version of the engine is peak torque at 5200rpm and I've drove one of them and it seems to be horrible for mpg but it also has a different transmission (3 speed no lock up vs 4 speed + lockup).

Btw, the corolla has nothing special about the oil system, so I changed it every 15k miles with quality synthetic oil. Not sure if 80k miles would be enough to see issues from it, but I haven't noticed anything yet besides the slight power drop. It had a sweet spot where the timing would pull back and mpg was great, a tiny bit more throttle and it would hit 39 advancement and mpg would tank 10% or so. The last 6 months or so I had a very hard time getting it into the sweet spot, that's the only way I knew it had less power (more throttle to go the same speed).

Also it's worth noting that rpm isn't everything when talking about MPG, generally speaking highest gear and going as slow as possible in said gear gives the best MPG, but different vehicles respond differently. My dad's Mazda 1989 (pre ford era) 2.6L 4x4 truck with 4.30 gearing would at best get 20mpg. He always shifted early and drove the truck easy. He hauled a ton of stuff with it and the mpg would drop a little but normally not bad if he wasn't trying to go fast (like over 50mph). When he bought his T100, he car dollyed it through Ohio and half of Michigan in 4th gear doing 3000 rpm and was getting 20mpg with the load. The T100 is physically bigger than his truck and sat much higher plus the dolly pushed it higher, so the frontal area was massive compared to empty. About the only thing we can think of is that engine likes higher rpm and we were driving it wrong for it's engine's wants. It was a DOHC engine and peak torque high up like the 1.6L corolla engine so it seems to relate to peak torque rpms a bit. I've seen other people mention it's related to piston speed (flame travel speed or something like that).

GM has a complicated system that uses oil pressure and "dirty oil" is a problem in this "system"

dirty oil clogs up passages and hydraulic lifter orifices, disallowing lifter function. then when it train wreaks you get a misfire and zero compression on a AFM cylinder
if a lifter gets stuck the engine needs to be replaced... or repaired BIG $$$$$

this is why i keep a 4,000 OCI using 0w30... oil is 100% clean still when i change it I don't let it get dirty... yeah i t could be recycled into another engine but a non complicated engine would be fine..

also i use 91 octane other wise the AFM system hyper cycles on and off with 87 oct... when it hyper cycles i get 18.5/18.5mpg which is the same as using 4speed mode with no Sun OverDrive gear 100% v8.. yeah this hybrid has a 4 speed automatic launch gearing ... funny how toyota 2021 thinks they're so special with the single speed launch CVT

me i have a 4 speed launch gearing 20.5 and 25 on the highway is what i get with 91 octane as it stays in V4 for longer periods (at lest tell it needs to recharge the vacuum system) I have been letting it warm up first in v8 mode...


City
87 octane 3.299= 0.178 per mile driven
91octane 3.599= 0.175 per mile driven

highway
91 octane 3.599= 0.175 per mile driven (20.5mpg)
91octane 3.599= 0.144 per mile driven (25MPG)


I really do want to do aero mods my target is the underbelly as should the target be on the F250 also an airdam




with the hybrid I should be able to easily get 40-50mpg with a few aero mod (it has very aggressive DCFO) the under belly is low hang fruit... as it's 100% Aero messy under there.



my trouble is keeping it in the Sun overdrive gear it's an Aero engine load issue.... if the wind is calm i can keep it in that Sun overdrive gear ... and get decent city mpg boosted upto 25 around town.. the highway is even better with a HIGH wind tail (20-25mph)wind i got 35mpg.... which is as good as a prius in the winter

[Piotrsko]

Aircooled bugs aren't happy in 110 degree heat pulling 5 mile long +3% hills. The palmdale to home pull crispied typically #1 cylinder sometimes #3. God help me if the wife had to hit second gear on the way home on the 6% hill out of Bakersfield. I did my own remans using only German parts because the wife was very fussy. Cold it was two kicks of the gas pedal and a key flick and it had better be running. One day the fanbelt had the audacity to break, so she immediately demanded and got a brand new car.

I believe the firing order of the 7.3 isnt left side right side, so that makes a crappy compressor

Which engine in the ranger? If you have a 90 degree six block, then it might work, I know a 60 degree will shake like a wet dog.

[ps2fixer]

Interesting you say a prius in the winter only gets 35mpg, any direct experience with that or just a joke? My corolla got around 38-40mpg in the winter, summer it was around 40-44mpg depending how efficient I was for the tank. Single trips I could get over 45mpg but never seen it as a tank average. I re calibrated the scan gauge every fill up.

My underbelly plan is to fix rust holes first, undercoat the body/frame etc, then work out an underbelly pan that's easily removable, and isn't too weak to be used off road. In front of the axle will probably be effectively a skid plate, center I'm thinking sheet metal with a frame so it can be removed with 4-6 bolts, and the rear section behind the rear axle doesn't matter much and should effectively never be needed to be removed, so probably sheet metal with a light frame. The rear bumper is OEM and a nice parachute too. It catches slush like crazy in winter lol.

Normally when I replace tires, I go oversized for the higher gearing effect, but for this truck, it seems to be about the perfect gearing for my needs and a mix of mpg. Of course I run max psi side wall pressure (or a little higher). I think the current tires were load range D so 65psi max. I don't really do city driving hardly at all, so the extra spinning mass is offset by the lower rolling resistance and the effect compounds when loaded (less tire sag).

So are you converting you truck to be hybrid, what's your plans on that?

Also ouch on your fuel costs, gas here is about $2.30/gal for 87 octane. Prem 93 (or higher) is $2.72, so mid grade should be about the middle at $2.51. Fuely doesn't have reported mid grade numbers (89 octane).

My LS400 calls for 90+ octane, but it pulls the ignition timing and runs on 87 just fine. The MPG does go down, but the difference in fuel cost, it's cheaper to burn more fuel at the cheaper price.

I wonder if you could somehow smooth out the cylinder deactivation system so it works well with 87 octane. If it worked right, then you might see better cost per mile with the cheaper fuel.



The launch control thing is kind of weird, you have gears, a CVT is variable gearing, it's effectively 1000's of gears, it's not an apples to apples comparison. Personally not a fan of CVT's, but there's pros and cons about them. In a race setup, CVT's can do really well, but for daily driving, I'd rather have real gears.

Anyway, didn't know how the cylinder deactivation system worked exactly, I guess the valves/cam system must use the oil to get the deactivated valves so the O2 sensor will be happy. I suspect the system probably works pretty good when it works, but like you said, when it fails it's not good. Powerstrokes are kind of in the same boat, when there's an injector problem, they are expensive to replace, but the whole engine doesn't need replaced or anything quite that extreme.

I did the math on an overdrive unit for my truck, assuming it got perfect results and the gearing increase gave that much in fuel savings, it would take something like 100k miles to recover from the initial cost of the unit. The propane route for me looks much more attractive since roughly 30% savings at $815 is something like 28k miles. A DIY system that's less optimized would be probably 1/4 the cost. Biggest thing is finding a proper tank for it. I suspect the ones on motor homes mounted to their frame would be acceptable but I'd have to research it a bit more. 20% propane vs 80% diesel would translate to about a 7-8gal propane tank, or ~30lb of propane capacity if I wanted to fill up diesel + propane at the same time.

Also interesting concept, I wonder if a gas engine would see any benefit from having propane added to it. I suspect gas burns more completely, so if there's any gains, I'm guessing there isn't much there. Maybe the octane benefit of propane could be of value though. Of course the computer controlled engines won't like it since the O2 sensor wouldn't be accurate (more fuel dumped in than it knows about).

Based on this page I guess the 6.0L is already a hybrid model? I don't really follow newer vehicles much. Pretty interesting the mpg range though, looks to be typically 17-24mpg.

If I jump over to my truck's year and engine, it's not looking so good, but I'm always at the upper end of the scale vs the average person. Typical looks to be around 15mpg, high end 20mpg.

https://www.fuelly.com/car/chevrolet...=&submodel_id=

https://www.fuelly.com/car/ford/f-25...=&submodel_id=

I wish there was a further break down for gear ratios and such. I don't know how common the 3.55 gearing was for my truck. In the city with normal drivers, I can see 15mpg being the norm with my truck though. With my style of driving, I'm too laid back and slow to get that bad of mpg even when I'm in a rush lol.

My Lexus on the other hand, it's behind on maintenance, same story bought it needing a ton of work. I have to replace the O2 sensors in it from a power steering line valve that went bad (the vacuum idle kick up valve), it ate power steering and killed the sensors. Seeing around 18mpg winter, and roughly 20mpg summer. I do have oversized tires and those are numbers before correcting for the tire size difference (about 5% bigger if I remember right). Looks like I'm getting about the typical mpg out of the car. I wonder if that's because people buying this brand have a different mind set, or my car is just running that bad to consume so much more fuel. It's extremely smooth running, just maybe it's dumping way too much gas.

https://www.fuelly.com/car/lexus/ls400/1990

[ps2fixer]

Originally Posted by Piotrsko

Aircooled bugs aren't happy in 110 degree heat pulling 5 mile long +3% hills. The palmdale to home pull crispied typically #1 cylinder sometimes #3. God help me if the wife had to hit second gear on the way home on the 6% hill out of Bakersfield. I did my own remans using only German parts because the wife was very fussy. Cold it was two kicks of the gas pedal and a key flick and it had better be running. One day the fanbelt had the audacity to break, so she immediately demanded and got a brand new car.

I believe the firing order of the 7.3 isnt left side right side, so that makes a crappy compressor

Which engine in the ranger? If you have a 90 degree six block, then it might work, I know a 60 degree will shake like a wet dog.

It's a 92 with the 3.0L v6, know next to nothing about them, not really a gas ford engine fan lol.

The 85 GMC 15 I have I'm pretty sure the 2.8L is the 60 degree or similar engine, that thing is so gutless even with all 6 cylinders firing though lol, floored top speed is about 60-65mph depending on the wind. It's an 87 fuel injected engine with the intake swapped over to carb and inline fuel pump added. Either the carb is wildly out of tune, or the fuel injection heads are very restrictive for the carb to work right. Either case, it 4x4's well for low range and low speed, just has no power to be road worthy so it's a yard beater (more like a yard sitter lol). I kind of have a personal junk yard.

I have a 1999 Camry out back that has a rod through the block, already one cylinder deactivated xD, it ran on the other 5 fairly well, it drove the 1200ft out back under it's own power, just doesn't sound too well, and it doesn't keep oil in the engine so well. The last owner said it blew on the expressway going 70 and he let it run very low or out of oil.

Anyway, I suspect it depends how each cylinder is clocked on the crank, or the firing order. I guess my lexus would be ideal for the firing order, it's a 90 degree engine with firing order 12345678.

Google says the powerstroke is 1-2-7-3-4-5-6-8, so yea it wouldn't be too balanced side to side, it would take some solid planning to do it right and both heads would have to be installed.

Too bad there isn't a bit more research on mpg besides the more extreme cases. Like having the peak torque lower in the rpm range I'd think would give mpg increases, but that would have to be paired up with correct gearing and such. I know my corolla vs the 1.6L version of the car, the 1.8L did much better, but it has lower rpm peak torque, and more gears and higher over drive etc. My cousin was getting about 33mpg out of the 1.6L with over 100k less miles on the car while I was pretty easily getting 40mpg.

[Tahoe_Hybrid]

Originally Posted by ps2fixer

Interesting you say a prius in the winter only gets 35mpg, any direct experience with that or just a joke? My corolla got around 38-40mpg in the winter, summer it was around 40-44mpg depending how efficient I was for the tank. Single trips I could get over 45mpg but never seen it as a tank average. I re calibrated the scan gauge every fill up.

My underbelly plan is to fix rust holes first, undercoat the body/frame etc, then work out an underbelly pan that's easily removable, and isn't too weak to be used off road. In front of the axle will probably be effectively a skid plate, center I'm thinking sheet metal with a frame so it can be removed with 4-6 bolts, and the rear section behind the rear axle doesn't matter much and should effectively never be needed to be removed, so probably sheet metal with a light frame. The rear bumper is OEM and a nice parachute too. It catches slush like crazy in winter lol.

Normally when I replace tires, I go oversized for the higher gearing effect, but for this truck, it seems to be about the perfect gearing for my needs and a mix of mpg. Of course I run max psi side wall pressure (or a little higher). I think the current tires were load range D so 65psi max. I don't really do city driving hardly at all, so the extra spinning mass is offset by the lower rolling resistance and the effect compounds when loaded (less tire sag).

So are you converting you truck to be hybrid, what's your plans on that?

Also ouch on your fuel costs, gas here is about $2.30/gal for 87 octane. Prem 93 (or higher) is $2.72, so mid grade should be about the middle at $2.51. Fuely doesn't have reported mid grade numbers (89 octane).

My LS400 calls for 90+ octane, but it pulls the ignition timing and runs on 87 just fine. The MPG does go down, but the difference in fuel cost, it's cheaper to burn more fuel at the cheaper price.

I wonder if you could somehow smooth out the cylinder deactivation system so it works well with 87 octane. If it worked right, then you might see better cost per mile with the cheaper fuel.



The launch control thing is kind of weird, you have gears, a CVT is variable gearing, it's effectively 1000's of gears, it's not an apples to apples comparison. Personally not a fan of CVT's, but there's pros and cons about them. In a race setup, CVT's can do really well, but for daily driving, I'd rather have real gears.

Anyway, didn't know how the cylinder deactivation system worked exactly, I guess the valves/cam system must use the oil to get the deactivated valves so the O2 sensor will be happy. I suspect the system probably works pretty good when it works, but like you said, when it fails it's not good. Powerstrokes are kind of in the same boat, when there's an injector problem, they are expensive to replace, but the whole engine doesn't need replaced or anything quite that extreme.

I did the math on an overdrive unit for my truck, assuming it got perfect results and the gearing increase gave that much in fuel savings, it would take something like 100k miles to recover from the initial cost of the unit. The propane route for me looks much more attractive since roughly 30% savings at $815 is something like 28k miles. A DIY system that's less optimized would be probably 1/4 the cost. Biggest thing is finding a proper tank for it. I suspect the ones on motor homes mounted to their frame would be acceptable but I'd have to research it a bit more. 20% propane vs 80% diesel would translate to about a 7-8gal propane tank, or ~30lb of propane capacity if I wanted to fill up diesel + propane at the same time.

Also interesting concept, I wonder if a gas engine would see any benefit from having propane added to it. I suspect gas burns more completely, so if there's any gains, I'm guessing there isn't much there. Maybe the octane benefit of propane could be of value though. Of course the computer controlled engines won't like it since the O2 sensor wouldn't be accurate (more fuel dumped in than it knows about).

Based on this page I guess the 6.0L is already a hybrid model? I don't really follow newer vehicles much. Pretty interesting the mpg range though, looks to be typically 17-24mpg.

If I jump over to my truck's year and engine, it's not looking so good, but I'm always at the upper end of the scale vs the average person. Typical looks to be around 15mpg, high end 20mpg.

https://www.fuelly.com/car/chevrolet...=&submodel_id=

https://www.fuelly.com/car/ford/f-25...=&submodel_id=

I wish there was a further break down for gear ratios and such. I don't know how common the 3.55 gearing was for my truck. In the city with normal drivers, I can see 15mpg being the norm with my truck though. With my style of driving, I'm too laid back and slow to get that bad of mpg even when I'm in a rush lol.

My Lexus on the other hand, it's behind on maintenance, same story bought it needing a ton of work. I have to replace the O2 sensors in it from a power steering line valve that went bad (the vacuum idle kick up valve), it ate power steering and killed the sensors. Seeing around 18mpg winter, and roughly 20mpg summer. I do have oversized tires and those are numbers before correcting for the tire size difference (about 5% bigger if I remember right). Looks like I'm getting about the typical mpg out of the car. I wonder if that's because people buying this brand have a different mind set, or my car is just running that bad to consume so much more fuel. It's extremely smooth running, just maybe it's dumping way too much gas.

https://www.fuelly.com/car/lexus/ls400/1990

you lose 20-25% in the winter because frozen batteries don't work well


Yes 6.0L it's just a gearing issue I lose a lot when i'm not in EVT mode (Sun overdrive gear this gets the RPM to 1,050RPM at 45mph the computer reads 45-49mpg inst .... at higher speeds the computer will stay in the 50-60mpg inst range when in the transmission is in EVT mode steady speed flat grade. ) which should net a minimum of 40MPG


but I see good numbers with it those numbers you see in my profile are combined or just city.. as i was too lazy to do individual "entries" so i combined a 300-400 miles worth of entries...



it's engine load dependent so i need to lower wind resistance or Aero drag..... I have to go after low hanging fruit as i don't want my SUV to look like a crab

Corrugated plastic = Polypropylene 158°-168° ignition temp 570°... i hope it will survive our hot summers

i.e underbelly seems to be the cheapest option it's 100$ to use plastic cardboard from front to back

don't forget about "oil changes and "moving" parts i.e drive shaft"


this is my fuelly https://www.fuelly.com/car/chevrolet...brent88/905265





I thought about using 100 octane unleaded but it's 10.90 a gallon.... i might go to the store and get motorkote octane booster ...

they "claim" it increases the octane by 10-30 points. so i will need 3 bottles to increase it by 10 points this will give me 101 octane unleaded.

also i gotta clean out the air filter it's plugged as i'm getting a hiccup on start up(it could be the weather causing it though as the traction battery is old and batteries are weak when they're ice cold I only have this issue on cold starts sometimes


i don't drive the rig much anymore since I have a corolla i able to use now that baby nets me 40-44 mpg... 100% stock...

[ps2fixer]

I think by points in octane is like 0.1. It would be simpler to state what the octane is of the actual fluid in the bottle and work out what it dilutes to when in the fuel. Either case, it will raise octane more for low octane fuel, and less for higher octane fuel. I doubt you can use bulk 91 octane and use octane boost to get into the racing fuel area (100+ octane).

Batteries physically how less energy when cold, so makes sense. Their amp rating and capacity decreases, but they still work just fine if designed for the weather, unless you're in Alaska or Canada or something like that.

What year corolla do you have, which engine? Mine was a 97 DX so it came with the larger 1.8L. 98+ had a completely redesigned engine that I wasn't too fond of. Not sure what was after that.

Ironically, I did look at your fuelly profile when looking at the figures.

My corolla doesn't have much of anything special about it, passenenger mirror delete, grill block, and I did a half engine bay belly pan. The under side was already fairly smooth, I don't think it did much for areo, the grill block might have helped slightly, and the passenger mirror helps maybe a tiny bit. I suspect my mods might be good for 2-4% gains. The biggest effect was driving slower everywhere and getting it in that sweet zone where the timing pulled back. I don't know what trips in that mode or why the max advanced timing is so bad for mpg in that engine, but I wish I knew more about what exactly was going on. Generally advancing the timing gives mpg increases unless it advances too far. Maybe it has a bad knock sensor or something and doesn't know it's going too far.

[Big Dave]

A few ideas that worked for me:

Electrically disconnect the EBPV. These things stick and you wind up running with a virtual exhaust brake in cooler weather.

Install a EGT gauge and drive the truck to keep EGT below 600 degrees F. Can be done but you need a very light foot. This falls under the heading of adjusting the nut behind the wheel.

Learn to coast. Easy with a stick. My ex used to call me Sir Coastalot. These trucks can easily coast a mile or more in the right situation.

Keep an eye on your rear brakes. For some reason these big Ford have a way of hanging up one or the other rear brakes.

[cRiPpLe_rOoStEr]

Originally Posted by Isaac Zachary

An "underpowered" engine on truck chassis would seem like an opportunity to add a hybrid system... If you're alright with the upfront costs of course.

That makes sense.

I've driven vehicles with over 30,000lbs over steep passes with less than 200hp. I wonder if there's a clear definition of what "underpowered" is or is it purely a personal point of view?

Believe me when I say something is underpowered, as from my Brazilian perspective I grew up around cars that would be deemed underpowered even in Europe or Japan. And you might have to agree with me that a 3-cyl 2.9L Diesel engine with only 67hp and nearly 145lb.ft. of torque, plus not being rev-happy at all, is somewhat underpowered for something like a C-20 or F-250.

[ps2fixer]

Originally Posted by Big Dave

A few ideas that worked for me:

Electrically disconnect the EBPV. These things stick and you wind up running with a virtual exhaust brake in cooler weather.

Install a EGT gauge and drive the truck to keep EGT below 600 degrees F. Can be done but you need a very light foot. This falls under the heading of adjusting the nut behind the wheel.

Learn to coast. Easy with a stick. My ex used to call me Sir Coastalot. These trucks can easily coast a mile or more in the right situation.

Keep an eye on your rear brakes. For some reason these big Ford have a way of hanging up one or the other rear brakes.

Nice to see you're still on the site. Your truck and mpg are some of the things I've checked into. On your truck's page it lists these mods:

Single-shot injectors & five position chip
203 degree thermostat

What kind of experience did you get with the chip, do you run it on a hotter setting, or just for the high idle for winter, or what worked best for you?

Did you see any benefits to the 203 degree thermostat over stock?

I haven't had my truck long enough to get super solid mpg figures, but right now it's looking to be about 20-26mpg depending on conditions (slow and steady long trips vs short trips, both numbers michigan winter based).

The exhaust brake is already disabled (it was cycling on and off even while driving). It also leaks a little oil I think from the valve or something in that area, so I'll probably have to buy the disable kit for it.

Earlier in the thread, it was suggested to run the truck effectively floored but shift early to keep rpm down. I tried that with my last tank and got about 16mpg, but there was a lot of cold starts and idle time. It was also the coldest time of the year (down to below 0f at night). My block heater didn't work either so it was 100% true cold starts with bad glow plugs in the system lol.

Do you still have your truck, I saw the last log is in 2010. I'm planning to experiment with propane injection (low to mild amounts, not for power, but for the mpg effect). Most people claim 25-30% gains in mpg, cleaner burn, oil lasts longer, lower EGT's at low loads, but higher at higher loads.

I do plan to get an EGT gauge, thanks for the number to target. Based on a video I watched, it looks to be real easy to keep it under 600 empty. I guess that would probably be a pretty solid "instant mpg" style gauge for my truck.

My truck does coast pretty well, I've still been getting used to it. My corolla could coast close to a mile on flat ground from 55mph, but I normally drove it 45mph back then and targeted about 1/2 mile coasts unless someone was behind me. I've probably been doing 1/4 to 3/8 mile coasts with the truck, spoiled by driving not for max mpg for a while.

I figured you didn't read the whole thread, so that should catch you up on pretty much everything about the truck.