Am I doing it wrong? Bad MPGs?

[142autox]

I can only manage about 14mpg driving as gently as possible. 93 W350 with the usual pump mods, turned in the power screw to the collar, fuel pin turned to the deep side, and star wheel down 1 1/2 turns.

I have a knocking injector and I'm thinking about getting the DDP stage 1ns. Pretty sure that at 225k I should replace them. Just hoping you guys can reassure me that I'm not throwing money away.
I've searched, and searched, it looked like the DDP is the way to go.

If I'm missing something please let me know, just trying to get decent fuel economy.

I've thought about turning the star wheel back up, and probably will, but I don't think that will net me what I'm trying to achieve.

[diesel freak01]

When was your last filter change? I know when my truck starts going downhill the fuel filter needs changed, same for the air filter. It also really depends on your tire/gear combo.

[RumbleFish]

Is your converter loose? That will eat mpg pretty quick

[142autox]

I just replaced the fuel filter today, I'll see if that helps. I really want to try adjusting the starwheel too but I will refrain and do one thing at a time. What I really wish I did was baseline it before I adjusted the pump, I marked everything so I can return to stock but I really don't miss the lack of power. The previous owner said that this truck would average 18 mpg. So either I messed it up somehow with pump tuning, the converter, or he was lying.

The converter is new, it's from Consolidated Vehicle Converters. I can't find the stall speed spec anywhere, I could hook up a tach and figure it out for myself. They're about 15 miles from my house so maybe I should just stop by and chat with them. I was going to order a Goerend but my rebuilder convinced me these are great.

I just got off the phone with DDP and they're convinced that they could help with my economy but the stage 1 injectors are out of stock for a couple weeks. I hope the knocking injector isn't hurting anything other that fuel economy.

Another thing to note: My last two tanks were with the front hubs locked, doubt it sucked up 5 mpgs though.

[CumminsPower59]

I know my 92 guzzles fuel when the hubs are locked, unlocking them and a filter change might help. Mine also got worse fuel mileage with the star wheel down, and with my 6x11's, I adjusted it up two turns from stock, so the fuel comes on a little later, when the turbo is spooled up more. Now, I have a valet switch on it, so when I want to go faster than half the speed of smell, I turn it on and away I go! Hope this helps ya!

Ike

[142autox]

Thanks for the heads up. I marked where the baseline setting was for the starwheel so if the filter doesn't fix it I'll adjust from there.

[Hansen01]

jus for a base my starwheel is down all the way and can easy get 21 on the highway, even 23 before. also when the front hubs are locked in i get crappy milage to, and winterfuel, or bad fuel really hurts them also

[142autox]

jus for a base my starwheel is down all the way and can easy get 21 on the highway, even 23 before. also when the front hubs are locked in i get crappy milage to, and winterfuel, or bad fuel really hurts them also

21mpg with the starwheel down? Maybe, you show you have a 6 spd. The rest of your statement doesn't compute though.

[Hansen01]

the swear check kinda messed it up when i got 23 it was actually with the 5 speed with the starwheel down all the way smoke screw in all the way, denny T2 and pump was a hair away from runaway, but my milage really drops when the hubs are locked in
dad continually gets 18 to 20 with his 93 and an auto with roughly the same settings
i would look into that injector like you said and then maybe the TC
also when winter fuel comes around up here i lose prolly 3 to 5mpg

[cmann250]

Maybe, you show you have a 6 spd

The NV5600 and G56 essentially split 3rd gear, I don't know which Hanson has though. They end up with an OD ratio of .73 or .74 and the A518 has a .69 OD ratio.

Also you have a dually. Those fenders and 2 extra tires eat up the mileage. Hopefully some dually guys will chime in to give an apples to apples comparison

[Hansen01]

*nv5600

[PToombs]

If you don't stomp on the skinny pedal, the starwheel adjustment doesn't mean any thing. It controls how much boost is needed to give it more fuel. If you stomp on it, the cone drops fast with the star wheel down because you build boost faster. If you step on it easy, it takes longer to build boost enough to move the cone. On mine, the cone starts to move about 12-14 psi with the star wheel down. If I hit it fast, it blacks out traffic. If I go easy, it barely smokes and I get good mileage.
Smoke = unburnt fuel = bad mileage.

[Philip]

Put a tach in and see what that converter is doing.

When I bought my truck it was getting 20 MPG. After I started adding goodies the MPG's started dropping. The tank before I did the G56 swap I was getting 14 MPG. After I did the swap I went to 19 MPG and its been holding steady around that every sence.

Going by my tach. The orginal converter was a good fuel eater. On take off it would take 2k RPM to get moving. If you stomped it going up a hill loaded or empty. It would go from the normal 1650 RPM at 60 MPH to 2400 RPM. After 5 seconds or so. Then the truck would start to pickup speed.

Remember you bought a converter someone rebuilt. Did they just open it up and say it looks good. Then weld it back up!!!!!

[142autox]

I wish there was an easy/cheap way to put a tach in for testing purposes. I have a gasser tach sitting in the barn but I'm certain it won't read one pulse per revolution. I know there's a converter you can buy but if I'm going to buy something it'll be a tach.

Every vehicle I've owned until this has been manual transmission, so I don't honestly know how it should feel. I should have stuck with the original plan of ditching the auto but it was more economical to rebuild, initially. From idle if I let off the brake it will pull it self forward, but the idle speed may be a bit high after adjusting the pump. I did drop it down a little with the idle screw but I left it up some to possibly help with winter warm up. It seems to pull well from a stop with only a 1/4 throttle, rpms do rise but they don't seem too high. 1/2 throttle I wouldn't say is much higher rpms just much more go, and full throttle usually results in tire spin. I have a couple good hills on the way home. If I mat it from a stop on a maybe 30% grade the rpms don't slip higher until I'm reaching the end of a gear, it'll hit maybe 22lbs of boost, and max out at 1,100 egt in a roughly 1/8th or so mile hill unloaded. I know this isn't good practice for good fuel economy, it's for testing purposes. Cruising at 55mph I can usually feather the throttle and maintain speed.

I'll find out next week if the fuel filter and unlocking the hubs helped, I'm cautiously optimistic. Couple weeks out on the injectors still.

[142autox]

Well I put in some new injectors, I went with the DDP stage 1 because they claim 1-2mpg increase. They delivered in SPG (Smoke/Smiles per gallon), but barely increased my fuel economy. I was getting 13-14 driving as gently as possible now I got 14.5mpg, I've even compensated for my odometer being off 16%, and I'm on winter fuel now. They are only smokey if I mat it from no boost but it quickly clears and I didn't do that even once during my test.

I'm going to try adjusting my star wheel up to see if that helps, but I doubt that's going to make up the 3 or so mpg that I feel that I'm missing. I've looked for leaks and haven't found any, and no I'm not making extra oil by mixing fuel in. Actually, I'm a quarter way down on the dipstick after 1,200 miles.

My daily driving conditions are a couple 2-3 mile 55mph roads then 35mph suburban roads. It drops into overdrive at 35 and it's barely chugging along, I thought that would give me good mpgs but I could be wrong. It's only about a 15 mile trip so it barely gets up to operating temp even with the radiator blocked.

I need some help fellas. This isn't cutting it as a daily driver.