Thoughts on MPG?

[jakcol997]

Ive noticed I am usually able to get around 10-12 MPG, but lately, im getting 6.8... is there any sort of suggestions/mods I can do to save my wallet the heartache??? I'm open to ANYTHING. once I get the extra $270, I'll more than likely get the newer injector. Just have to save up a bit!

 

[bigdog9191999]

tune up stuff, tires ect all play a part. that is pretty bad tho, I am not getting that bad with my 8.1. with that noticeable of a drop there has to be something. any codes? even if not may be able to get some basic data and compare to normal ranges.

 

[drakon543]

my 97 does pretty good generally but alot of differences in your vehicle to mine can have an effect. however a drop in mpg like that you probably have something wrong. when was the last time a proper tuneup was done. how many miles are on the truck. can you give us any specific details like do you know what gearing you have in the rear. knowing more details can help the people more knowledgeable with the 90s trucks know where your mpg should be.

 

[jakcol997]

my 97 does pretty good generally but alot of differences in your vehicle to mine can have an effect. however a drop in mpg like that you probably have something wrong. when was the last time a proper tuneup was done. how many miles are on the truck. can you give us any specific details like do you know what gearing you have in the rear. knowing more details can help the people more knowledgeable with the 90s trucks know where your mpg should be.

I just did a full tune up- plugs, wires, cap, rotor, air filter back in October, did an oil change on the like 3rd of February, my rear axle (positraction limited slip dup of 5x1) is 3.73. That’s what google told me with my RPO Code! I’m riding with 265/75R/16 trailfinders, no lifts or anything like that.. what more info could ya need?

 

[jakcol997]

I just did a full tune up- plugs, wires, cap, rotor, air filter back in October, did an oil change on the like 3rd of February, my rear axle (positraction limited slip dup of 5x1) is 3.73. That’s what google told me with my RPO Code! I’m riding with 265/75R/16 trailfinders, no lifts or anything like that.. what more info could ya need?

I just filled up with gas. Trip read 156.7 miles and had to put 19.7 gallons in. That clocks me at about 8 mpg..

 

[iCajun]

Is it also harder to start when hot? I had a bad fuel pressure regulator some years ago.

 

[Doubeleive]

low efficiency catalytic converter can cause low mpg's

 

[jakcol997]

Is it also harder to start when hot? I had a bad fuel pressure regulator some years ago.

It starts perfectly fine when it’s hot out!

 

[drakon543]

ya pretty sure you have something going on. not sure what to point you at but you should be able to get better than that. maybe your cats are getting bad forcing the engine to struggle more to do what it should be able to do. intake gasket maybe but id assume you should be seeing other symptoms besides poor gas mileage.

 

[jakcol997]

ya pretty sure you have something going on. not sure what to point you at but you should be able to get better than that. maybe your cats are getting bad forcing the engine to struggle more to do what it should be able to do. intake gasket maybe but id assume you should be seeing other symptoms besides poor gas mileage.

Any suggestions on what to buy?

 

[Kelsda]

It starts perfectly fine when it’s hot out!

How’s your exhaust is it blowing black smoke (dumping fuel)I get around 14.5 to 15 highway before I did new injectors just finished Thursday hope to get better numbers on this tank of fuel

 

[jakcol997]

How’s your exhaust is it blowing black smoke (dumping fuel)I get around 14.5 to 15 highway before I did new injectors just finished Thursday hope to get better numbers on this tank of fuel

Wellll... I don’t have a tailpipe... but I never see any sort of smoke!

 

[Kelsda]

Wellll... I don’t have a tailpipe... but I never see any sort of smoke!

How much of your exhaust is missing your other post has exhaust codes maybe fix that first? Exhaust builds up back pressure necessary for valves to stay alive

 

[drakon543]

you definitely need the correct exhaust velocity. i must have totally missed your post with the obd 2 codes. where are you on those. intake leak could cause some of those other codes potentially but again i think you would notice other symptoms aswell. you could check for intake gasket leaks by spraying carb cleaner or starting fluid around the edges of the intake. if there is an immediate change in rpms in a certain spot when your spraying it thats your leak.

 

[jakcol997]

you definitely need the correct exhaust velocity. i must have totally missed your post with the obd 2 codes. where are you on those. intake leak could cause some of those other codes potentially but again i think you would notice other symptoms aswell. you could check for intake gasket leaks by spraying carb cleaner or starting fluid around the edges of the intake. if there is an immediate change in rpms in a certain spot when your spraying it thats your leak.

Dumb question, but where would my intake be? Or what does it look like?

 

[drakon543]

its the thing that sits under the thing that your air filter intake tubing is attached to lol. the intake manifold top of the engine its the whole thing that sits between the valve covers.

 

[jakcol997]

I might be following, like I've said in my previous posts, I know nothing about cars, I'd love to learn and get comfortable working on mine... its cheaper in the long run. I've Been contemplating putting a crate 5.7 in it.. yay or nay? after all this is fixed, of course. haha.

 

[drakon543]

your looking at about 1400 for just the block and heads you would need to transfer everything else from your engine. not to mention its still not something i would suggest for a novice without someone there to help.

 

[Kelsda]

Dumb question, but where would my intake be? Or what does it look like?

Here’s the upper intake ( black plastic) lower intake
( aluminum) out and reassembled this is a big job to take on for some even though others say maintenance it’s buried under a lot of sh#t ask a friend to possibly point you in the right direction google or YouTube has videos on checking for leaks

 

[drakon543]

couldn't ask for better pictures to know what your looking for. and it is definitely a big job and a bunch of ways to make it worse than it already is.