Thread: Is This a LTFT issue?

My car sucks on gas. I did a tune up (wires, plugs, filters, o2), even cleaned the MAF, but still no good. My DIC says i'm getting 17.9, but i'm putting $30 in almost every 3 days. It had this problem after i began modding (maybe before, i dont remember) but after a tune, it wasnt a big difference. Are my fuel trims not correct?

o, idk...i have no way to scan. I was just curious if my trims are off, could that be an issue. the guy who tuned it for me lives a little over 2 hrs away and i wanted to see if maybe there could be something else i could possibly try before biting the bullet and making the trip again.

Originally Posted by wpbboy81

My DIC says i'm getting 17.9, but i'm putting $30 in almost every 3 days.

This helps nothing in the diagnosis. Tell us your usual MPGs to compare. Or give the type of driving.

I'll see if he can hopefully email me the tune results.

Originally Posted by Pure2sin

This is why if you mod your car the most important things to get are:

-A wideband O2

-Some way of scanning the car-DHP, HPT, Aeroforce or even the app from Android called Torque.

^^ yea, you're right. i kept putting that off. i got a scan gauge II but it doesnt really do me much good. I wanted to get the DHP or HPT, but i've never used any of those programs, and was intimidated by nt knowing how to use them, so i figured i'd let someone who does do it for me instead.

Originally Posted by mechguy

This helps nothing in the diagnosis. Tell us your usual MPGs to compare. Or give the type of driving.

i would have to calculate it. my DIC normally says anywhere between 14.5-15.9 MPG. I usually drive maybe 10 over the speed limit (most are 45) city. most of my driving is highway when i go to work which is aout 10 miles away. but since i've noticed the hole this is burning in my pocket, i'e been doing the speed limit everywhere, staying in the slow lane, and easing off at stoplights. it doesnt seem to make much of a difference.

Just so its clear, your DIC currently reads 17.9MPGs, while your usual is 14.5 to 15.9.

Yet your actual MPG is lower now despite the higher reading?

i wouldn't say lower, its about the same as before. i dont trust the DIC anyways. if i reset it it'll say im getting 27 MPG or some high figure, then gradually drop to wherever it wants. No matter if i speed or drive slow, the #s dont change more than a few 10ths. I drove a 14' uhaul truck to orlando and back (2 hrs) and only had to fill up once, still had 1/2 tank when i got back. I drove my car to orlando and back and filled up before i left thn again before i came home.

do you ever fill your car all the way up then reset the trip then fill it up again when it needs it and figure up your mpg? Thats the only true way to tell.

I've reset it after fill up, but usually forget to check it before adding gas in again. Im going to try it today, but its just bothering me that i just put 30 in saturday, then again yesterday (1/2) and already down to 1/4 tank. I thought i found the prob a long time ago, because my fuel line was leaking by the filter, that was only a minor improvement

Originally Posted by dsmuts

do you ever fill your car all the way up then reset the trip then fill it up again when it needs it and figure up your mpg? Thats the only true way to tell.

Originally Posted by wpbboy81

i wouldn't say lower, its about the same as before. i dont trust the DIC anyways. if i reset it it'll say im getting 27 MPG or some high figure, then gradually drop to wherever it wants. No matter if i speed or drive slow, the #s dont change more than a few 10ths. I drove a 14' uhaul truck to orlando and back (2 hrs) and only had to fill up once, still had 1/2 tank when i got back. I drove my car to orlando and back and filled up before i left thn again before i came home.

First : Dic reads total average mpg not instant. So it is constantly dividing miles driven/ gals used. As the miles become larger the changes get smaller .

Second : Truck was full when you picked it up, doesnt matter how many times you filled the car, HOW MANY GALLONS DID YOU USE ?

Originally Posted by GTP in RTP

First : Dic reads total average mpg not instant. So it is constantly dividing miles driven/ gals used. As the miles become larger the changes get smaller .

Second : Truck was full when you picked it up, doesnt matter how many times you filled the car, HOW MANY GALLONS DID YOU USE ?

the truck had 1/2 a gallon at pick up, got to orlando almost on E, refilled it and got home..only used 1/2 a tank both each trip. I filled my car tank up, drove to the hotel, then disney, was a 1/4 tank when i refilled it for the ride home. was at a 1/4 when i got here....used about 3/4 each way....thats like 12 gallons

ok, im not sure how this goes, but my fuel trims according to my scangauge II range at idle (-15 thru -18) long, and (-2 thru 0) short.....when cruising it ranges (12-15) long and (0 mainly) short. idk how to tune, but im guessing these #s arent good

I'm pretty sure they are supposed to be +-5. What are they are WOT?

Originally Posted by dsmuts

I'm pretty sure they are supposed to be +-5. What are they are WOT?

i gotta go drve it again...i wasnt sure if i was supposed to jot those #s down

At WOT they're both at zero

That's a good thing.