Thread: With a few mods, will a tune help MPG?

When I put in my downpipe, I didn't notice a difference in MPG, then when I put on the PLOG and TDC FWI I am now seeing about a 1-2 MPG drop in MPG. I know that it doesn't seem like a lot, but I am just wondering if a light tune would help this at all? At first, I chalked it up to just hitting WOT more so that I could hear the supercharger whine, but I've backed off of that and still see a drop. I was running a very consistent 19.5 MPG average with my mix of city/highway driving. Now I am sitting at 18 MPG with my "back to normal" driving. Details of my vehicle are in my signature below.

more timing = better gas mileage, so in short yes. i noticed a 2mpg+ increase in my car when i raised the timing during cruise.

Tuning can always tune out better fuel economy...but a canned tune will not be the way to do it. It takes a touch of effort using a tuner to get the most out of it.

I was given the offer from another member here to "drive over" and he would put on some basic tune parameters for free. He lives about 3 hours from me, but I start a new job on Monday that will put me about half way between here and there, so it might be worth the trip, depending on what he can tune for me for free...

you wont really see much with a simple tune. youd need a lot of driving around and tweaking in order to get a great tune for MPG reasons.

OK. So then is the reason that I am seeing a drop in MPG because I am increasing the air flow in (and out) of the engine, and the PCM is compensating for the increased air by throwing in more fuel to prevent it from running lean? Or am I totally off track?

Have him at least throw the '05 timing tables on there, as that will help and is a good place to start anyway.

Originally Posted by nickbuol

OK. So then is the reason that I am seeing a drop in MPG because I am increasing the air flow in (and out) of the engine, and the PCM is compensating for the increased air by throwing in more fuel to prevent it from running lean? Or am I totally off track?

you are right. more air means more fuel.

not a whole lot without adding more mods to it.

I'll be doing the tuning. Depends on how much time we have or what you want on the car, we can get it dialed in good enough for mostly stock car. I just tuned a regal that we Intercooled and he said he noticed an increase in gas mileage, that was with a 3.2" pulley and 2-3 degrees of added timing on a 12.1 A/F ratio, for a non-IC car you want it to run a little richer 11.5~. Most of the time we are tuning to make power and do not look into mpg, it's just a bonus if we gain mpg. There are some spots in the cruising timing that we can raise to gain mpg on the highway, but I have not looked into that much. I'm sure I can figure it out by then if your looking for more mpg and a lil more power tune.