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Suddenly no throttle

Summit Racing sells both 3.73's and 3.42's for $200-$250 but not sure that is the direction I want to go just yet. still looking a other less expensive mods I can do and still keep the towing capacity it has now. I priced everything I need for the DIY water injection, that comes out to around $175 and the more reading I do, it seems to have more benefits to it than just mileage while still keeping most everything stock. Lower EGT temps, lower overall engine temps, cleaner engine, and added power if done right.
 
dbrannon79 said:
getting 14.1 mpg.
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Full Stop. That's about as good as you can expect. You are not going to get your money back on any mods to improve in that number. Best money spent would to be GET SOMETHING ELSE. Plenty of coffin on wheels 50+ MPG gocarts , err, cars out there. Modern 1/2 ton pickups with gas engine get ~18 MPG as well as 3/4 ton diesels.

I had both the 3.73 in a 1995 burb and the 4.10 in a pickup. Same MPG unloaded with the 6.5TD of around 14 highway and 10 city. Towing the Asthma Attack turbo hits 7 MPG with some serious grades involved. A 454 gasser drinks about the same amount of cheaper fuel towing... The back pressure on a GMx turbo is insane: another Mediocre GM diesel feature.

Swapping the turbo for something larger can pay for itself on this engine when towing. My MPG went from 7 to 10.4 towing with a larger turbo. Some towing turbo's don't light off till 2000 RPM. Then they pull like a fright train past redline. It's a different lean you back in the seat than the choking all blow and no go feeling. I put a high stall converter on my larger turbo setup to get the engine in it's power band from a stop light.

No smoke on a small 6.2 pump, ATT turbo, with the Yank high stall converter here:

 
most of my highway driving is usually under 65. even the trip I took to Austin the other day I stayed between 60 and 65 due to traffic speed on I35. there was one time back in the summer where I had actually got up to 16 MPG but I think I had to have been light footing it the whole time. I actually wish there was a device made for these ODB1 trucks that could be plugged in and show the realtime MPG's like they make for the OBD2 models. I had one on my old 4runner that helped me lighten my foot. lol at times I made a sort of game out of it trying to keep the numbers climbing :p

I've often wondered with my knowledge if vehicle electronics if I could take one of these cheap monitors and modify the connectors and make it work on the OBD1 setup. I know with some (not all) GM 95 pre OBD2 systems you could technically re position the pins in the OBD2 connector to the right places in the ODB1 plug and the code scanners would work as they were meant to! Somehow I feel this 95 truck has the ability of this scenario. GM did a lot of experimentation on earlier years just months in production before a major change like the "pre OBD2" but still called them OBD1 systems. again, I couldn't treat it like this because not all parameters would work as they would on newer vehicles, but technically it should be able to read sensor data. but that's wishful thinking!
 
Yeah, those numbers are pretty dang good especially not having vacuum controlled turbo.
You could do a bit better I think with att for the dropped back pressure and higher pop pressure injectors. But not a ton better.

Drop the gearing and you might need more throttle to maintain speeds. Thats a gamble.

Less weight, tires withless rolling resistance, the minor aerodynamics improvements like lowering the headache rack out the wind, figuring how much radiator blockage could be done, But again all really minor improvements.

Another 10% would max you out I think, and cost a few grand to do it.

I think if cost of operating is still too high, you need to really look at wvo fuel or similar.
Maybe look into other long term money savings like top end synthetic oil and a centrifuge to keep it alive as long as possible.
 
Most mpg is obtained driving at peak torque output RPM, drag starts to pull at around 45 MPH +-, a tight low stall will yield more MPG while a higher stall will yield less. The 6.5td peak torque RPM is 1.8k.
Most vehicles have a higher stall than advertised peak torque output RPM, why? I suspect torque converter torque multiplication is why.
 
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I did another mileage calculation and again I was at 14.1 MPG. Just had my alignment done and a tire rotation so I'm hoping to see something better since the mechanic found that the drivers side caster/ camber was way off!

something I have been searching for and can't seem to find anything on it in the forums, I had read where someone had mentioned they had setup a laptop on their truck to show the real time fuel economy while driving. I want to ether find or build some sort of display that would show the real time mileage and / or the average fuel mileage while driving. I can't remember if the free version of GMTDscan will show this or not. even if I can modify one from a junk/donor vehicle to work with the OBD1 and the 6.5 data. I've got a good place in the dash to put something like this, right where the OE disk player was. if the GMTD will show this, I was thinking about one of those cheap raspberry pi mini computers to leave in the truck to do just this and possibly other functions.
 
One of the clearer answers linked below I have seen if you are obsessed with MPG. You are on the right track.

Unless it's coming off your bottom line (running commercial) IMO your eyes are best kept on the road not some lie-o-meter for instant MPG. Your ECT, engine temperature, is way more important and way more expensive if overlooked and allowed to go over 210.

www.turbodieselregister.com

Towing fuel Economy

The instantaneous mpg will probably be better than egt for economy. That being said I do like having the CTS2.
www.turbodieselregister.com www.turbodieselregister.com
 
I know those Lie-o-meters aren't intended for accuracy, but I'll admit they do help you keep your foot out of the floor when your paying attention to them! my goal here is to be able to increase my average mpg's from what seems to be 14 as a daily drive to somewhere between 16 and 18 depending on how much highway driving I do. I know if I were to pull off the tool box, headache rack, bed rails, and the front brush guard I would probably achieve that right off the bat. but I feel like there are other maintenance repairs and low cost small mods I can do to achieve this and still keep my "junk in the trunk" so to speak!

I do have a list of things to to for maintenance that may or may not help me reach that goal but one thing I am doing is tracking mileage in between each item on my bucket list. one of my next things is to replace the injectors with some good bosch ones. I think in the beginning I may have screwd up by replacing them with some reman injectors from the local auto parts. the white smoke and long crank time seems to be getting more and more pronounced on morning startups and after sitting for several hours in the day! my valve cover gaskets have started to leak more now, so I think I'm gonna gather all the parts in the next few weeks and do the intake and valve cover gaskets and hit the injectors again at the same time. Then look at replacing the waterpump and doing a timing chain before the good ole Texas summer is on us again!
 
Keeping speed down, use cruise control all you can, tire pressure set to proper patch print, are all instant changes you can do right away to make a big difference. Unhitching the kia from the truck and driving it instead also helps. Haha
 
Well I feel real dumb right now! I had an idea of trying to build an injector pop tester using a bottle jack and some fittings. Well I had grabbed a couple of metric hydraulic fittings from work and went to pull a fuel line off just to make sure I had a fitting that works. Well when I went to pull the fuel line off the drivers side front injector I found the injector was loose in the head :banghead: I swore up an down I had torqued them when I had installed them but I’m getting a knot in my gut telling me I forgot to double check them!!! I was able to get a full 1/4 turn out of that injector tightening it up so much that I had to swap the return lines so they wouldn’t be kinked! Damn I feel like a doe-doe head finding this mistake. I left the others alone at least until my other half lets me spend more money on it! Maybe if I just order one at a time she won’t notice lol but for sure it’s an injector job for me again.
 
Will L. said:
Confused. you damaged 1 line and it needs replaced? Or you did it to all 8?
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I had replaced them back in the summertime with reman ones. I just went to pull off one of the steel lines from one of the injectors to make sure I found the right fitting so I could build a pop tester. When I tried loosing the line nut on the number 1 injector I found that injector was loose where it was threaded into the head! Only reason I’m doing this is I feel like there bleeding down overnight (longer cranks and white smoke every morning). And since I need to do the valve cover gaskets I plan to order new Bosch injectors but before I install them again I want to be able to to test each one for bleed off pressure and such
 
Will L. said:
Ahh, now I get it.
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Lol after tightening up the loose injector I ended up flip flopping return hoses. She still runs and purrs like a “diesel” kitten so I’m hoping I didn’t make that mistake on the others not double checking the torque back in the summer when I had installed them.
As for making a diy pop tester I had read a forum somewhere a guy used a cheap bottle jack, pulled the ram and used a fitting with a gauge and line. Filled with clean diesel for a dirt cheap way to test them.
 
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