ok. idk if this was said or not, because im too impatient to read the whole thread. run one tank dry, fill it with an exact amount, and run it dry again. then you will have your fuel mileage to a tee. i do this all the time on my 460. honestly dont know if its kosher to do that to a diesel, but its and idea.

 

The power is OK, but nothing out of this world. My 0-60 is 15-16 seconds shifting at around 3400. I haven't checked that since I fixed all my air leaks- that could've cut a lil.

The oil pressure is fairly low, or the gage isn't reading right (it sits halfway between red line and the "n", about 1/8 to 1/4" into the while line)
Truck has 204K, and some blow-by, but it's not too bad. The IP and injectors have less than 20K on them (PO is a honest guy, I believe him)

 

460/5

I have run out of fuel a couple times on the highway and while its not the end of the world, its not really good for the fuel injection system either (fuel provides lube). I prefer to simply average tanks instead, although your idea would be one way to eliminate fuel up error for a one time test senario. However, I haven't been seeing much in the way of errors from the fillup pump.

Chevy 6.2D

1988 doesn't have a real oil pressure gauge. Instead it simply has an on/off pressure switch that turns on at the 7 psi mark. Your low oil readings are probably due to a weak connection at the sensor. You can change the sensor and mod the cluster to read dynamically like trucks older than 1987, but most just go with an aftermarket gauge instead.

Power seems to be on par for a non turbo diesel. Economy is lower than what it could be though. Without knowing more its hard to speculate on what could be wrong. Timing is the only thing I can think of.

 

With the way the tanks are in these trucks, the only real way to figure fuel mileage is averaging several tanks.

The slightest difference in how the truck is sitting can cause the front tank to take a lot more or less fuel since it is so long.

Rear tank is not as bad, but front end up or down hill does make a difference.

When I fuel, I use the same pump, drive in the same way every time and fill the spouts completly full.

The MPG changes every time.

 

Front and rear tanks seem to be pretty consistent for me. Station lot is completely level so thats not an issue either. I've been running the same route, fuel fillup pump, and conditions for the last 3 years now. Lately I know how much fuel I burned before I put the nozzle in the filler flute. I got pretty good with my F150's fuel up numbers too back when I was still driving it. Some gas station attendants were surprised but I don't see what the big deal is in when you stay with one vehicle for so long.

MPGs do vary, but I found that has more to do with traffic, my driving style and weather conditions than the shutoff of the pump. Cool damp (but not raining) days like that last one consistently give me 20 MPG, while rainy days consistently keep me below 18 MPG. Rain and wind cap me at 16 if I insist on holding the speed limit.

I had railings in the bed on the way home so the tailgate was down and some parts were hanging out the back by a few feet. Doesn't sound like much but it adds up. Thats why I wasn't able to quite hit 20 this time. If I limited myself to 70 top speed I probably could have made it. The one time I hit 22.5 MPG in this thread was with a "load" so small that I had the gate up for both ways and box was practically empty. That almost never happens.

The results are accurate enough for me to consistently average better MPGs heading north than south no matter what tank is used in either direction. Reason being the prevailing winds near the highway route.

Using larger fillups also helps reduce errors. Filling up with 3 gallons won't be as accurate as 15. Thats another reason I stopped switching tanks at the halfway point. I'm only interested in the average, not how a slight tailwind can skew the results. Now that I know the reason behind the north/south direction discrepancy, there is no point measuring it everytime.

Wonder what a bumper to bumper bellypan would do for a truck like this, but I don't have time to build something like that. Maybe some day.

 

That's what I thought, I have a mech OP gage lying in the garage somewhere, have to find the line for it or get a new one.

My MPG could be somewhat due to the front brakes dragging. I hope to get those fixed in a few weeks.

I need to get my hard cold starts figured out. I either need batts, and alterntor, or both.
While the glows are on the volts are down in the red, after it is running, the volts stay around 10 for a while. When the glows cycle (engine running) the gage barely goes up when they turn off. I have seen other trucks where the gage quickly jumps up.

After glows are off it takes a few minutes but the volts eventually come up to 13 or so. I'm thinking replace the alt first. A 90 AMP lifetime warranty is $90 from o'reillys

 

.....................double post.

 

David,
check this out sometime would ya?
SuperMID - Fuel Economy Display - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com

here it is with pics:
crxMPG – Gas mileage never looked so good » SuperMID: Fuel Economy Display

hopefully i get my timing meter working soon (having a OBN member test my crank sensor for me etc.)

easily incorporated for use with our trucks?

would be pretty dang sweet to monitor mpg's in real time,while i tweaked timing and different speeds to see how much the big bed hates me,also help tweak some home made air deflectors for it.or possibly just redesign the whole front section into a strange ugly looking air streamed mess haha.i don't care.when ya drive 15k miles per year,every mpg adds up.

also i wanted to ask you,
how much do you feel a better built aftermarket torque converter plays a role in fuel economy? and do you have a suggestion for any in particular?

i did not know this.that would totally suck not to have OD most of the time.


update after about a years worth of ownership now:
nope.it's not another story.
she'll still toss me back in the seat a bit and take off faster than i normally ever would when empty,even while loaded up.i do it every once in a great while lol.but it's a waste of fuel of course,and hard on things.
so if your idi feels like a dog,it's likely well overdue for a tune up.

full time tree service truck(seasonal.winter while plowing,i don't bother reporting.thats measured in hours really,not miles.)
'93 f-250 dually conversion.e40d auto trans.4wd.8x9 enclosed stake body dump.3.55 axle gears with shorter tires = to 3.84 gearing with stock tires.65k original miles.
15.87 AVG MPG @ AVG of 50 MPH.As SRW.(yeah i had the big dump bed on then too.)
currently @ 14.73 AVG MPG as SRW and DRW combined @ 41 tanks.
loads of 1 to 3 ton along with towing little 1 ton chipper often.


current mod in progress:
electric engine fans.

eventual goal:
16 AVG MPG.
(likely a turbo is required to reach this.along with more aerodynamics of the dump bed.)

im thinking of 215/85/16's - stock dually tires as opposed to my 225/75/16's
i went lower for ease of loading bed.but it's only a half inch difference,would give me a 3.70 gear ratio (so id never notice this really) but most importantly,would give about 2 and half inch less tire width combined.thus im thinking,may be good for another .5 mpg.
i think i'll try this size next time.

 

You been doin some thread digging XLT

 

yeah.this site has so much to offer its incredible.
the search function has been my friend for so many things it's not funny.
no idi owner should be without this site.

 

I agree, but this search engine turns up blank for a lot of questions I have. And then when I ask the question, someone posts a past thread on exactly what I wanted to know and I always wonder where they found it. Oh, well...

 

That meter seems to be designed to wire into an EFI system so I'm not sure how well it will work on a mechanical engine. EFI engines use the computer to fire the injectors (no news there) and its those signals that the OBD can be used to monitor with devices like this. Since there are no sensors anywhere in an IDI diesel like ours to monitor fuel flow rates, I don't think this will work. What you would need for an IDI is something to monitor both the inlet fuel flow and return line flow and display the difference in the cabin. There might be something like that out there but I never looked into it since I calculate my MPGs at every fillup. Having the direct feedback from in the cab would be nice though.

As for torque converters, I don't think fuel economy will be much different unless you are spending a lot of time below the lockup speed. The main thing I was concerned with was durability which is why mine is a tripple clutch billet converter (there are some other things in it but I can't remember them all).

EcoModder is a pretty good forum but I haven't really felt the need to register there yet. Most of what I read pertains to electric cars since there is some rather clever members there on the topic of motor controllers. One guy was able to build some pretty darn good controllers. I wonder if his 3 phase controller is finshed. Hope to get mine running again pretty soon!

Over on OBN some one posted a link of some on in SanFransisco that hypermiled his 6.9 up to 27 MPG. Base model, 2wd, regular cab, 4 speed stick, and side wheel covers on the bed made of plywood, but it worked! To my knowlege that was the second highest MPGs ever posted by an IDI. The highest being an F150 that was converted to diesel and could get roughly 30 MPG with a used 7.3 non turbo.

Turbocharging will have almost no improvement at the lower end of performance in terms of MPGs, however when you start loading the truck down or if you drive around with a sail like that dump bed, you could see more benefit. For heavy loads and big trailers, the most likely result is more speed fro the same amount of fuel. Usually most of us are having too much fun to really notice a lot of MPGs added on.

 

i forgot to thank you for your reply.
thanks David.

here's a hypermilers tip id like help with,and or some more understanding.
trucks with A/C i noticed the compressor power becomes hot with the selector on MIX and DEFROST and not just the two A/C settings.
my fuel economy drops big time when i use the A/C (if i left it on for a full tank lets say,i would easily be down 2mpgs if not 3!yeah,ok so maybe something is wrong here and should be addressed before next summer.)
anyway, i noticed this when i wired up my newly installed electric fans (of which i'll report my findings here shortly once off this winter blended crap,and no longer pushing snow around.)
so simple trick for winter would be to simply unplug that dang a/c compressor so it wont turn on.
this is fine for most,and will do the trick to save fuel for many,however i can't have my engine fans come on every time i want to use MIX or DEFROST either(yes i could unhook the trigger to relay too,but read on.)
(little off topic.but once i unplugged the a/c compressor i found i had to jump the low pressure switch so i can control my e-fans now if i want via turning on the a/c.i wont leave that jumped when i do hook the compressor back up in the summer though,don't worry.)

long story short,
i would like to still have MIX and DEFROST of course,but id like to bypass the signal given to the A/C compressor for good,so that in no condition,at any time will these settings ever turn on my compressor or fans.however i still want the A/C settings to remain as stock of course.
anyone able to tell me how to do this?
yes i know i could do other things,but really want it as described.why? just so i can always turn the fans on manually,without running a devoted switch.and in the summer i don't want either setting to turn the A/C compressor on,let alone engine fans when i do plug it in either.

 

You could do one of two things, depending on how automatic you want it to be.

One, you could install a cutoff switch that can be turned off when you set your control to Mix or Defrost. You would have to run some wires either from your heater control wiring or the AC pump itself that interrupt the circuit. Keep in mind that the AC clutch draws a fair amount of power, so you may need to use a relay.

The other option; if your heater control has separate wires coming out of it to control your AC pump (e.g., one wire for AC/Max AC and one for Mix/Defrost), you could cut the wire that powers the AC clutch when the heater control is set to the Mix/Defrost positions. However, I suspect that your heater control might have only one wire that powers the AC pump in all four positions. In that case, you would have to dig in to the control itself, which may not be easy for you.

You may want to consider option 1. The reason the AC pump comes on in the mix/defrost positions is because conditioned air is also dehumidified air. There will be times that your defroster is unable to clear your windshield without the AC pump. If you have a cutoff switch, you can use the AC pump when it's needed and keep it cut off when the defroster is able to clear the windshield without the AC pump.

 

The reason the A/C runs while in the defrost mode is moisture control. I think you will find if you unplug the A/C you will be constantly wiping the fog off the windows on the inside while you are plowing and running the the heater on defrost. It might not be a problem with just you in the truck, but it gets worse the more people inside the vehicle. Also getting in and out of the truck often with wet snowy boots, gloves and coats makes it worse too.