FJ60 4BD1T MPG

[muttsinapig]

Hi all, I have searched the forums and please redirect me if there is an answer out there already! I have an FJ60 with an Isuzu diesel swap (4BD1-T). After several years and maybe 20K miles, I would guess I have averaged 17 mpg. I have seen other posters here, as well as the PO, say that they get 20 mpg or more. I did not change anything from the PO's set up--I still have the 35's, didn't mess with the pump, same exhaust, etc., and the PO and I both drive basically like middle-aged men not out to race anyone.

So, I'm wondering whether there is anything I can look at in order to achieve the previously-reported mileage claims. I don't see puddles of fuel as if it is leaking which would explain poor mileage, tires are the correct pressure, brakes not dragging, I don't have the truck loaded down, didn't add a rack to it...basically the same vehicle. Thanks much!

 

[Dougal]

US gallons or real gallons? There's ~20% difference.

What's your driveline, gear-ratios and what speed do you drive? Highway or stop/start? Tyre size? Tyre type? Lift? Roofracks?

 

[muttsinapig]

Thanks...US gallons.

1989 4BD1-T (no intercooler).

A440 trans., stock Toyota FJ60 transfer case.

I believe stock 3.73 axle ratios.

325/70/17 (35") tires on FJ Cruiser rims with spacers--Mastercraft Courser Radials (look like BFG A/Ts sort of).

SOA on stock FJ60 springs.

No roof rack. Heavy-ish front and rear bumpers. No winch.

Mostly city driving 7 or 10 miles up to 25 miles each way to office or field site five or six times per week. I drive pretty much the speed limit and the bits of highway I am at 1800-1900 rpms at the max, which is about 70-74 mph indicated. I have driven some exclusively highway trips, and I did get a bit better mpg on those trips (18 or 19 mpg).

I appreciate the response! Mike

 

[handcannon]

I may be wrong as I don't have any direct experience with a 60 series. But, didn't the later 62 series with the auto transmission go back to the 4.11 gears? Early years with the manual transmission got the 3.73 gears.

Don

 

[Dougal]

Thanks...US gallons.

1989 4BD1-T (no intercooler).

A440 trans., stock Toyota FJ60 transfer case.

I believe stock 3.73 axle ratios.

325/70/17 (35") tires on FJ Cruiser rims with spacers--Mastercraft Courser Radials (look like BFG A/Ts sort of).

SOA on stock FJ60 springs.

No roof rack. Heavy-ish front and rear bumpers. No winch.

Mostly city driving 7 or 10 miles up to 25 miles each way to office or field site five or six times per week. I drive pretty much the speed limit and the bits of highway I am at 1800-1900 rpms at the max, which is about 70-74 mph indicated. I have driven some exclusively highway trips, and I did get a bit better mpg on those trips (18 or 19 mpg).

I appreciate the response! Mike

So in metric (because I work in metric and litres/km don't change) 18 USMPG = 13 litres/100km.

If you were to swap your 35's for 31's, put the springs back under the axles and drive at 65mph I think you'd get down to ~10 litres/100km (23-24 USMPG).

I don't think anything is wrong, I think your usage, travel speed and vehicle height are the main reasons you're burning more.

My 4BD1T does 10 litres/100km on normal road trips, 12 litres/100km with more offroad travel and gets under 10 litres/100km if I'm stuck in slow holiday traffic on long trips.

 

[muttsinapig]

@handcannon. I believe you are right, but this was a custom swap, originally 4BD1T to NV4500 which was switched out for an A440 with came from an FJ62, yet the Fj60 axles were retained.

 

[muttsinapig]

@Dougal. I don't disagree, but the PO said he was getting 20+, even 25 with this exact setup. Maybe he does math a little differently or found a way to always drive with a tailwind, I don't know. But it seems that for some reason, 20 mpg (US) is a mark that folks selling cars/trucks always seem to claim, and I have no reason to disbelieve him save for the fact that I cannot reproduce those numbers! And, I got a good deal on the truck so I'm not mad at him, just trying to understand if something is amiss with the vehicle.

I saw an ad recently, and there are multiple ads on the same vendor's website, for vehicles such as Unimogs (curb weight say 3350kg or 7300#) and it says with a 5.9l 6-cyl diesel they get 20-25 mpg (8.5 to 10.5l/km). So...either again this guy is using funny math, or my 5800# (2600kg) vehicle with a 3.9l 4-cyl. ought to acheive 20 mpg. For example: FJ40, FJ45 & FJ55 Toyota Land Cruisers Call 24/7 (313) 414-3540

I'm not trying to beat this to death, and if I should be happy at 13-14l/100km for mostly putting around town, then I'm happy. Still might not understand the others' claims, but I can let that lie (no pun intended).

 

[Dougal]

@Dougal. I don't disagree, but the PO said he was getting 20+, even 25 with this exact setup. Maybe he does math a little differently or found a way to always drive with a tailwind, I don't know. But it seems that for some reason, 20 mpg (US) is a mark that folks selling cars/trucks always seem to claim, and I have no reason to disbelieve him save for the fact that I cannot reproduce those numbers! And, I got a good deal on the truck so I'm not mad at him, just trying to understand if something is amiss with the vehicle.

I saw an ad recently, and there are multiple ads on the same vendor's website, for vehicles such as Unimogs (curb weight say 3350kg or 7300#) and it says with a 5.9l 6-cyl diesel they get 20-25 mpg (8.5 to 10.5l/km). So...either again this guy is using funny math, or my 5800# (2600kg) vehicle with a 3.9l 4-cyl. ought to acheive 20 mpg. For example: FJ40, FJ45 & FJ55 Toyota Land Cruisers Call 24/7 (313) 414-3540

I'm not trying to beat this to death, and if I should be happy at 13-14l/100km for mostly putting around town, then I'm happy. Still might not understand the others' claims, but I can let that lie (no pun intended).

Yeah internet MPG claims usually fail to deliver! But you should get your 20mpg on a good run at lower speed.

A stock diesel 100 series burns about 12 litres/100km.

 

[muttsinapig]

Yeah internet MPG claims usually fail to deliver! But you should get your 20mpg on a good run at lower speed.

A stock diesel 100 series burns about 12 litres/100km.

OK...I'll go away happy! Thanks for the advice. I do still love the truck...

 

[doug720]

I have a similar swap - 1985 60 with 4BD2+H55+3:70's+10.50X33's+ roof rack w wind deflector+ ARB/Winch front bumper- stock rear bumper+ AC. It has a stock NPR intercooler+NPR wastegated turbo+IP fuel turned up about 10%.

I drive 65-70 mph and over 50k miles it has averaged right at 20 mpg - US gals. I can drop down to 17 at times, and maybe a little better than 20 at times, but 20 is average.

Have you checked you ODO with 35" tires? With 33's on mine, the stock odo is about 12-13% slow - odo reads less miles than actually traveled! Without correction, 35's would be 20% or more off.

20% off would get you to 20 mpg easily!

If you corrected for tires, the auto is likely reducing your mileage also. I read an article comparing the same vehicle with a manual and an auto trans. It showed 1.5 mpg reduction for the auto trans.

 

[muttsinapig]

The speedo/odo has been corrected professionally, I guess you could say, at a speedo shop here with a custom ratio adapter box. Seems to be fairly consistent with my phone’s GPS reading.

As far as manual vs auto—thank you, I’m not a huge slush box fan already, even one that is built to the hilt, so more reason for me to go back to a manual!

 

[bugsnbikes]

how many miles on the 4bd1t??

slushbox kills a few mpg’s easily......and if your turbo is on its way out and the 4bd1t compression is low or its just an old engine.....you can easily add another 1-2mpg hit minimum. add another 1-2mpg hit if you in fact have 4:11’s and you are looking at 4-6mpgs already below where a newish engine/properlygeared/manual tranny will get.

Not to mention thst the i.p. likely isnt functioning 100% if it needs a rebuild if the engine has 300k miles vs 30k miles.

with the amount of unknowns- id say your mpg is reflecting some or all of the above.

a compression test and checking of rpm/speed in gears will determine 2 of the above potential mpg losses.

Longbowdon was netting 25-26mpg with a light 40series on 35s/3.73/h55 prior to his swap to a440 which dropped it a few mpg.

so a heavier 60series and brand new engine with a440 and 3.73 “might” get 22ish with a brand new engine..........and work your way down for things like bad gearing,tired i.p., tired motor,tired turbo, etc.

 

[muttsinapig]

I love my engine and I am working on engine #2 to put in my 40 right now. 23-25 MPGs in my 60, can't wait to see whatkind of mileage I am going to get in the 40! 6/10/2012.

That is a quote from longbowdon, and he built and previously owned the truck I now drive. I believe the motor had 36k on it and might have 55k on it now. As I may have said before, I don’t doubt Don‘s numbers, my quest here is to figure out whether something happened to the truck under my care that I need to remedy in order to get the numbers that he said he was getting. That laid out there, my very first tank hit about 16 mpg so I’ve been scratching my head for about 2-3 years. He and I live in the same town, and likely share similar driving habits, as well as similar traffic patterns, as the whole town is pretty much stop light to stop light every mile. I still have all the same equipment on the truck save for changing out two tires about a year ago to a different tread pattern but with no change in fuel consumption.

Thanks to all here for the suggestions so far! Mike

 

[gerg]

If your getting that kind of milage and it's mostly city I wouldn't be too upset.

 

[mattressking]

Stupid question but what tire pressure do you run?

 

[muttsinapig]

Good thought for sure, and just a small correction: the tires are 315/70r17, not 325. But you all probably knew that...

I’d say I run them at 42-45 (at the very most) lbs. They are on FJ Cruiser 7.5” diameter rims which is a touch narrow (8-11” recommended) and might pinch the tires a little more than desired, so I don’t like to go to max. inflation in order to avoid more rounding than necessary.