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Help, 6 mpg!!! Why!!!!!?????

4X4HIGH said:
I learned ALONG time ago to never ASSUME anything. When you assume it makes an ass out of you and me. :thumb:

How do you know you're doing 2000 rpm's at 60 mph? Did you use a GPS or your speedo? If using your speedo it is not correct because of the tire size change.
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Oh yah i know, its just the guy kept everything stock except for the carb intake and distributor, i just dont know why he would have put anytihng else in it. Maybe. But i changed the fluid only a couple months ago and its too friggin cold right now to do it again haha, cuz whaatever i got is gonna stay in it for a while, bad mileage costs less at the moment then a grand or more to have new gears installed. just lookin for little things to check
 
K5dreamer said:
www.fuelly.com

im signed up and use it for both my truck and my jetta. the home page has lots of tips on how to drive, and tips for best fuel economy. The number one method to improve fuel economy is the "right foot mod" by far.

swapping out those 4.56 gears for a set of 3.73's would do ya good. ive got 33in tires, a TH400 trans, and 3.08 gears... and a diesel. so i get 15mpg around town, and 21mpg or so on the highway.

but with a 700R4, you should be doing well better than your current mileage. a carbed 305 with super deep gears is not a recipe for great fuel economy im afraid. try and find a TBI setup at the junkyard and upgrade.
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Its not the "right foot thing tho, i mean a little spin in the snow every so often wouldnt matter that much but i take it easy all the time. And i do let it warm up for a good 15 min every morning so im sure its more like 8 or 9 or something, but i just boiught and put on tonight a PROHEAT oil pan heater. Reveiws on them were awesome. GUys said in -20 they would plug it in 2 hours or so (or have a timer) before they got up in the morning and the oil would be up to 60 by the time they got in. Hopefully reducing hard starts and burning the gas better when its cold. And i just wanted it lol
 
The best way to "warm" an engine up is by starting it and only letting it idle long enough to build oil pressure then drive it. Letting it idle for 10 or 15 minutes isn't helping anything.
 
4X4HIGH said:
The best way to "warm" an engine up is by starting it and only letting it idle long enough to build oil pressure then drive it. Letting it idle for 10 or 15 minutes isn't helping anything.
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Which is why I bought the heater. No warm up. Plus it's nice to be able to have the ice melted off the windsheild before I take off at 6 every morning.
 
4X4HIGH said:
The best way to "warm" an engine up is by starting it and only letting it idle long enough to build oil pressure then drive it. Letting it idle for 10 or 15 minutes isn't helping anything.
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Really??? I always warm up my truck. I like a warm heater/defrosted windows and like my truck to be at operating temp when I leave the driveway. Is this an old dead practice? :dunno:
 
An engine will heat up quicker by driving the vehicle rather than trying to let it "warm up".
 
COCHEV said:
Really??? I always warm up my truck. I like a warm heater/defrosted windows and like my truck to be at operating temp when I leave the driveway. Is this an old dead practice? :dunno:
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Idling if usually pretty hard on an engine. The main reason for letting a truck warm-up by idling for 10-15 minutes is for driver comfort. Most of the trucks with diesel engines advise against letting a truck idle for any amount of time, and many newer ones will raise the idle speed up significantly if you let it sit and run after a few minutes because the higher engine speed is much easier on the engine than normal idle rpm.
 
4X4HIGH said:
An engine will heat up quicker by driving the vehicle rather than trying to let it "warm up".
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What you warm climate folks seem to forget is that a vehicle can not be operated if you can not see out of it. Whether or not you think warming the engine is "good for it", it is much better for the truck than smashing it into a pole or oncoming traffic is.
 
Are you sure of the rpm? I assume the tach is aftermarket. And are you sure of the speed? If you are just making short trips and you are warming up the truck first, 6mpg is about right. If the speedo is wrong, your odometer is wrong and therefore your MPG calculation is wrong.

It isn't really designed to get double-digit MPG in the city, but should get 15 on the hwy if everything is OK.

I don't know if this was mentioned, but check the base timing and make sure the vacuum advance is working.
 
6.2Blazer said:
Idling if usually pretty hard on an engine. The main reason for letting a truck warm-up by idling for 10-15 minutes is for driver comfort. Most of the trucks with diesel engines advise against letting a truck idle for any amount of time, and many newer ones will raise the idle speed up significantly if you let it sit and run after a few minutes because the higher engine speed is much easier on the engine than normal idle rpm.
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So why does everybody with diesel engines always keep their trucks running for ever instead of turning them off if its so bad, wouldnt less rpms be easier on moving parts? My buddies cummins has like 300000 on the motor and lets it idle all the time, no problems yet???
 
Deuling said:
So why does everybody with diesel engines always keep their trucks running for ever instead of turning them off if its so bad, wouldnt less rpms be easier on moving parts? My buddies cummins has like 300000 on the motor and lets it idle all the time, no problems yet???
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Alot think its harder on the engine (starter mostly) to start and stop them.
 
Blue85 said:
Are you sure of the rpm? I assume the tach is aftermarket. And are you sure of the speed? If you are just making short trips and you are warming up the truck first, 6mpg is about right. If the speedo is wrong, your odometer is wrong and therefore your MPG calculation is wrong.

It isn't really designed to get double-digit MPG in the city, but should get 15 on the hwy if everything is OK.

I don't know if this was mentioned, but check the base timing and make sure the vacuum advance is working.
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Yah im sure it is off a little bit and yes sunpro tach so im sure it could be off. But im filling up rediculous amounts, like loosing an 1/8th of a tank a day, and i live 5 min from school and work. Must be a twenty gallon tank. Im getting roughtly 100 miles, (on my tach) on 3/4 of a tank. 100/15=6.66. On the highway i average about 50 miles a quarter which comes out to about 10mpg. Do you think 32inch tires would throw the odometer off that much?? I dont really know the stock tire size but they couldnt have been that much smaller. But possibly i guess.

Thanks for agreeing with me on the idling thing haha. Glad to have someone from the cold area. If anybody has ever put oil in a clear bottle in 0 degree weather they would know that it gets very thick and almost doesnt move when tipped upside down, then try to lubricate your engine with that lol. I think the reason an engine warms up faster when very cold and you just leave is because their is not enough oil on the moving parts to lubricate them properly, which most likely causes the pistons to eat up the block, then you have bigger problems. My theory.
 
Blue85 said:
What you warm climate folks seem to forget is that a vehicle can not be operated if you can not see out of it. Whether or not you think warming the engine is "good for it", it is much better for the truck than smashing it into a pole or oncoming traffic is.
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sick truck by the way, was it a pain to put the newer clip on??
 
I don't think you ever answered for certain what gear ratio is in there. If you don't know how to check it, search (I'm talking about physical verification - RPO codes don't help).

This lets us know if the gears are part of the issue, but doesn't tell us anything for certain about the speedo/odo. If somebody has been swapping parts they may have changed speedo gears - a shop may have even done it as part of a gear swap without the owner knowing. The best way is to check the actual distance traveled either with GPS or by noting the mile markers on a long freeway trip. Then you will know the ratio of your odometer vs. actual and can calculate your true MPG. It also lets you know how much the speedo needs correction.
 
jack the rear up, mark the tire and drive shaft with chalk. spin the tire one complete revolution and count how many times the drive shaft spins. this will give you the effective gear ratio and things can be figured out from there. a 31" tire was a common factory option, a 32 shouldn't throw off the speedo "all that much" if all else is stock. i see no reason to be running that intake/carb setup either. drive down the road side by side with a buddy and a known good speedo, note yours when he hits 60....
 
Blue85 said:
I don't think you ever answered for certain what gear ratio is in there. If you don't know how to check it, search (I'm talking about physical verification - RPO codes don't help).quote]

Yah i know how to check it i beleive, carriage teeth divided by pinion teeth right?? i Just dont wanna go out at the moment and drain my rear end, just did it a couple months ago and yes i know i was stupid to not check it then, but oh well. Im gonna try what the next dude wrote and jack the rear up and mark the shaft and tire and get an estimate. Ill try it tomorrow after work and let you guys know. It may not be 3.73s just at the moment its pointing to it because the tag says limited slip, and i have a limited slip. I know somebody could have put another in. Ill letcha know:waytogo:
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shovelbill80 said:
jack the rear up, mark the tire and drive shaft with chalk. spin the tire one complete revolution and count how many times the drive shaft spins. ....
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So how do i calculate the ratio off of that?? like say im thinkin its 3.73s, how many times should the driveshaft spin?
 
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