Engine/Transmission (1994 - 1998) injectors vs mileage

[LVJUNIOR]

How has aftermarket injectors effected your fuel mileage? I keep trying to pull some mileage out of this thing to no avail. Has anyone changed back to stock injectors and seen a significant gain in MPG.



Please specify the make and stage of the injectors if there was a change.

 

[fest3er]

I didn't notice any change in mileage when I swapped in the 215HP injectors in place of the OEM 160s. The thicker the black smoke, the more unburnt (wasted) fuel is going out the tail pipe. If the exhaust is clear or is a slightly grey haze, the engine is running efficiently.



There are three ways to increase fuel economy:

1. Keep yer foot out of it.
   
2. Install a freer-flowing air intake.
   
3. Advance the injection timing; 3-4 degrees should show a difference.
   
4. Install synthetic lubes all 'round.
   
5. Ensure the front end is properly aligned.
   
6. Ensure that there are no worn-out components in the steering, suspension and drivetrain.
   
7. Use tires with less rolling resistance.
   
8. Trade it for a Yugo. (Well, maybe not. )
   

 

[MAleshire]

The mileage will increase with the Yugo, because you'll be towing it instead of driving it.

 

[LVJUNIOR]

I didn't notice any change in mileage when I swapped in the 215HP injectors in place of the OEM 160s. The thicker the black smoke, the more unburnt (wasted) fuel is going out the tail pipe. If the exhaust is clear or is a slightly grey haze, the engine is running efficiently.



There are three ways to increase fuel economy:

1. Keep yer foot out of it.
   
   H
2. Install a freer-flowing air intake.
   
3. Advance the injection timing; 3-4 degrees should show a difference.
   
4. Install synthetic lubes all 'round.
   
5. Ensure the front end is properly aligned.
   
6. Ensure that there are no worn-out components in the steering, suspension and drivetrain.
   
7. Use tires with less rolling resistance.
   
8. Trade it for a Yugo. (Well, maybe not. )
   

I have done everything on your list except the Yugo and the tires. I need the mud terrains. I still can't get more than 400mi out of a tank

 

[CCiatteo]

So what kinda mileage are you getting with your truck, 13-14mpg? Looking at the mod list I'm guessing that isn't horrible all things considered. What kinda mileage are you hoping for? Sorry I don't have any of my own experience to offer, but I am curious.

Chris

 

[46mech]

Put the same injectors into my 160hp motor that fest3er did; no change in my mpg's. When I advanced my timing to 16. 5 deg, I got about 1. 5 more mpg out of it. The truck does 15-16 mpg's in combined city/hwy driving and about 21 unloaded on the hwy. It is 2wd though.

 

[LVJUNIOR]

I am getting about 13mpg. I have added timing a cam a ported head and my mileage hasn't improved a bit. I was hoping to get 16-17 empty on the highway.

 

[fest3er]

I have done everything on your list except the Yugo and the tires. I need the mud terrains. I still can't get more than 400mi out of a tank

At stock settings, my '98 12V 160 engine has given me 18. 5-19. 5 MPG on the highway for 250K+ miles. 215 injectors made no noticeable difference. Sliding the stock plate forward and adjusting the AFC for little smoke made no noticeable difference. The 3K GSK made no noticeable difference. The extra 50# of 19. 5" tires made no noticeable difference. Maybe I just got lucky. The mudflaps and bug deflectors made no noticeable difference.

What weight and combined weight are you running? Are the rear brakes hung up?

How much fuel do you call a 'tank'? For me, a tankful is 32-36 ga. I rarely refuel before the needle is just below the E mark.

Is your speedometer/odometer accurate? Drive 100 miles up the highway; note your odometer at the first mile marker you see. Then note your odometer one hundred mile markers later. Then subtract your first odo reading from your second reading, and divide by 100 (miles). This will tell you fairly accurately how far off your odo/speedo are.

So if your odo shows you travelled 80 miles, then divide your mileage by . 8 (80/100). 400 miles out of 30 ga. of fuel will turn into 16. 6 MPG, which isn't too bad. An unladen non-CA 12V truck ought to get 500-650 miles out of 32 ga. of fuel.

As a last idea, do you smell #2 oil near your truck when there are no other sources of #2 nearby? If so, fix the fuel leak.

[EDIT: with 35" tires, and uncorrected speedo/odo, your elapsed mileage should be off by about 18%; correcting this puts you at about 16 MPG. ]

 

[LVJUNIOR]

No hung brakes no fuel leaks odometer is dead on both by mile marker and GPS methods truck is about #9000 going down the highway. I know I won't ever see 22mpg with my set up but 12-13 seems ridiculous.

 

[Extreme1]

I was getting 18 on the interstate if I drove less than 70. As the speed went up, the milage went down fast.



I've got a Goerend trans, a PDR modded 215 pump (16. 5 timing), 370 injectors, a PDR HX-40, 4" exhaust, a 24 valve intercooler and a free flowing intake. But I run skinny tires (215-85-16's). Duallys make better anchors than mudders.

 

[fest3er]

Are your valves well and properly adjusted?



Are you certain your p-pump timing is correct?



Are you certain the injector pop-off pressure settings are correct?



Try running Amsoil or Stanadyne cetane booster in a tank or two of fuel.



If you're running a 3. 54 rear end, you should be turning about 1600 RPM at 70 MPH or so, which is *way* under the BSFC rating of the engine. 4. 10s with those 35" tires would put you closer to 1800 RPM.

 

[CToney]

My sweet spot on my '97 was 1750. I ran it at 2000 rpm most of the time. I would get over 500miles out of a tank easy. It was a 5sp 4x4 with #10 slid back and a small resonator for a muffler. I did put new 215's in her which gave me more boost and lower egts. The extra weight, tires, and reduced aerodynamics has you paying more per mile. The auto is a big problem too.

 

[hsmith]

I have 3:54's and 70 mph is close to 2k rpm's. In 5th OD I drop it to around 1750. My truck has never been a economy maker but has always been around 19 to 20 before and after mods. Biggest factor is the right foot.
Also towing 14k plus as around 12 mpg.

 

[LVJUNIOR]

Are your valves well and properly adjusted?



Are you certain your p-pump timing is correct?



Are you certain the injector pop-off pressure settings are correct?



Try running Amsoil or Stanadyne cetane booster in a tank or two of fuel.



If you're running a 3. 54 rear end, you should be turning about 1600 RPM at 70 MPH or so, which is *way* under the BSFC rating of the engine. 4. 10s with those 35" tires would put you closer to 1800 RPM.

P-pump timing has been checked twice



injectors have been redone a couple of months ago and are all poping off at the same pressure



I ran stanadyne for 500mi and without it for 500mi and no difference.



I am running 4. 56 in the rear which gives me around 2200 at 75mph.



Here is the latest. I drove 500 miles to my hunting area at 75-85mph (2100-2300rpm) checked mileage and got 12. 35mpg drove to the mountain off road and back to town 100mi total got 12. 38mpg drove 500mi home at 75-85mpg and got 12. 85mpg loaded my 5th wheel drove to barstow and back at 60-70mpg (1700-2000rpm) and was down to 1/8th of a tank after 380mi.



I hit the scales and with the 5th wheel on it it was only 13,900lbs total. I will weigh the truck by itself tommorow but anticipate somewhere between 8500 and 9500lbs



I have thrown everything but the kitchen sink at this thing to no avail. I am stumped.

 

[HerbW]

I have about the same year and truck as yours and it's even red! Though I have stock 17" alloys and tires off a 2007 Big Horn and my mileage is pretty good. I got 17 MPGs pulling my 20 foot trailer loaded. The worst I've ever got is 16. 7 MPG ever. I have a TST number 8 plate in stock location without a kat and a straight thru 4" muffler system and stock 3. 54 axles. I've gotten over 20 MPG if on a long drive in OD. That's all I've done. I think your knobby tire resistance could be costing you plenty. Also if some of your measured travel is in 4x4 or low range, on snow, mileage is out. I have heard the front bumper like yours can also affect mileage due to the weight. I read it can cost 1. 5 to 2. 0 mpgs. It would be interesting to put less resistant tires on and strip down your truck in the summer and measure what MPG's you get. Good luck, Herb

 

[LVJUNIOR]

Finally got my truck weighed its 9360#

 

[CCiatteo]

9360#???? I think my truck is 6600-6800#. Is my memory shot and I'am not remembering what my truck weighs or are you carring lots of extra gear? Bumper and tires don't add up to 2500#.

Chris

 

[LVJUNIOR]

I have a lot of stuff mounted to my truck. tool boxes fuel tank generator, spare 35" tire, axe, shovel, 2 winches, custom bed, etc. It s heavy.