Engine/Transmission (1994 - 1998) Where should I set the timing for best mgp?

[CBrabec]

Earlier this year I had some work done to my truck (i. e new transmission, injectors etc) and the guy who did the work says he set my timing to 16*. Now when I bought my truck used it was bone stock and the mgp were about 11-12 in town. After all this work my truck now gets anywhere from 8. 5-10mpg in town. With my mgp getting worse, I called back to the guy who did the work and he swears he did the timing adjustment, but when I looked closer I see no signs of any of the bolts on the timing cover look like they had a wrench on them. I called and talked to Ole Poole, who specializes in the 12v's and he told me with the new injectors my timing needed to be done or my mgp would suck. I am going to be doing my KDP fix here in the next few weeks and I would like to check the timing to make sure it was really done. I do mostly (90%) of my driving/towing in town daily and was wondering if 16* is to high for timing for my mgp or should I set it at 15*? With $4+ fuel prices, every mpg better I can get will be greatly appreciated.



Chris

 

[Bill Lins]

Mine's at 15 per Dr. Joe Donnelly- mpg went from 17 to 19+ afterward.

 

[MChrist]

Would the timing be different if you use different injectors?

 

[CBrabec]

Olee told me the best aftermarket injectors are DDP's for the 12V's and he said with any aftermarket injector that will increase the HP you need to adjust the timing. I don't know which company John at Floor it Diesel got my injectors from, he won't tell me. When we dyno'd the truck these injectors gave me about an additional 55hp. Olee said even a bad set of aftermarket injectors will drastically decrease the mpg along with the timing not done correctly. I'm told these 12V's are touchy when it comes to setting everything correctly. If I had put in a stock set, then I don't know if the timing would needed to have been done, but I tow a lot and needed more power so I went with the new injectors

 

[CBrabec]

Well here is an update, I had a local comapny called Husker Diesel install new DDP 75hp injectors, adjusted my timing to 16. 5* after they found out the timing pin was broke, got the KDP fixed, pump bench tested (all good) and all new seals put in, had new 4. 10 gears installed and my in town fuel milage went from the crappy 8-10mpg to 15. I'm happy with the results, but am still wondering if 15mgp is what I can expect. Is 16. 5* timing still to high? Like i said earlier, 90% of my driving/towing I do is in town. My truck is a reg cab, 4wd, auto with stock size tires. I was really hoping for 17-18 around town, so not sure with my upgrades what other guys with 4wd trucks are getting for mpg.

 

[GAmes]

You aren't going to get 17-18 around town. My wife's Toyota minivan barely gets that. For what you spent on labor you likely could have bought a timing kit and then could try different settings. There is no one size fits all, but I think 15mpg is about as good as it gets for in town driving.



BTW, the reason you saw "no signs of any of the bolts on the timing cover look like they had a wrench on them. " is because the nut for the IP is behind the oil filler tube. To set the timing that is all that has to be removed.

 

[hsmith]

I would add that 15 around town with 4:10 gears is not bad.

 

[DRAG DIESEL]

with 600k of experience this is what i find yields me the best milage:

when my rpm average is:
1600-1700rpm - 12*
1700-1800rpm - 13. 5*
1800-1900rpm - 14. 5*
1900-2000rpm - 15*
2000-2100rpm - 16*
2100-2200rpm - 16. 5*
2300rpm+ - the more the better

 

[Missouri Mule]

Especially when your towing!

 

[CBrabec]

Drag Diesel, I think you are refering to (*) as the timing degree to each rpm range? Well like I said most of my driving/towing is done in town so I would guess my rpm ranges are usually 1700-2000 most of the time. So maybe I should lower my timing down a bit come spring time.

 

[DRAG DIESEL]

Drag Diesel, I think you are refering to (*) as the timing degree to each rpm range? Well like I said most of my driving/towing is done in town so I would guess my rpm ranges are usually 1700-2000 most of the time. So maybe I should lower my timing down a bit come spring time.

Yes. . i don't know how to type the little circle for degrees.

 

[GAmes]

So maybe I should lower my timing down a bit come spring time.

Not necessarily. The bigger injectors might make your setting where it should be. If you pay to have it done you might never make up the cost with improved mileage.

 

[DRAG DIESEL]

If you pay to have it done you might never make up the cost with improved mileage.

that is a major factor. we are talking 1 to 2 mpg differences with each setting... TOPS!

 

[LNaugle]

i think with your current setup that your mileage is average... deffinetly comparable to similiar trucks i have had experience with.

 

[crabman]

You have a automatic with 4wd & 4:10 gears, each one of these reduce mpg. If you had a 2WD, 5 speed & 3:73 gears then you could better MPG easily.

 

[JMcCoy]

Your right foot makes a big difference too. When my wife drives my truck (3/4 highway 1/4 in town) she gets 21 mpg. When I drive the truck, 17! Go figure

 

[Bob95065]

Yes. . i don't know how to type the little circle for degrees.

ALT+0176



I have a 1997 4x4 5 speed with 3. 55 gears. Lightly loaded I get 23. 5 MPG on the highway. In town it drops to less than 17. When I tow on the highway it also drops significantly. I am planning a trip to help a friend move at the end of the month. I will pull a 6x12 U-Haul trailer 500 miles one way. I am curious to see what the mileage is with the trailer and without it on the way home.



I am running 256/75 R15 tires. I really wish I had 3. 73 gearing. I think it would improve my in town and towing mileage.



I have a friend that has a bone stock 96 that he bought brand new. It has 4. 10 gears. He gets 20MPG no matter if it is in town or highway.

 

[BigPapa]

I am running 256/75 R15 tires.

Huh? Maybe you mean 265/75R16's?

 

[Bob95065]

Huh? Maybe you mean 265/75R16's?

Yes 265/75R16. I went up a tire size which hurt my in-town and towing mileage.