Lost MPGs

[maestromaestro]

So, I had the tranny rebuilt, and, naturally, “while there”, ended with a new clutch (AP Racing) and flywheel and the Wavetrac LSD.
Also, switched to Dizzy Stage 2 tune (was running OTS Cobb Stage 3).

Now, what I see is that I went from about 28.5 mpgs to about 25 mpgs. Everything else - where I drive, how I drive, gas station/fuel that I use - is the same. Same tires, same pressure. The weather is pretty much the same as well.

Curious. Is there more friction/energy loss because of the LSD? The transmission is not native, but from a donor - otherwise, nothing else that comes to mind.

Suggestions?

 

[kivnul]

Mine went down a tad with my mfactory lsd. About 5% or so. While there I also replaced clutch & flywheel but I stuck with OEM.

 

[PunkST]

More moving parts use more energy.

 

[DEss]

Also, switched to Dizzy Stage 2 tune (was running OTS Cobb Stage 3).

Now, what I see is that I went from about 28.5 mpgs to about 25 mpgs.



Suggestions?

Go back to cobb stage 3

 

[maestromaestro]

Go back to cobb stage 3

Hmmm... I don’t think that the tune can be responsible for such a massive loss. The Dizzy tune, based on the butt dyno, provides a more smooth delivery. Care to elaborate?

 

[DEss]

Hmmm... I don’t think that the tune can be responsible for such a massive loss. The Dizzy tune, based on the butt dyno, provides a more smooth delivery. Care to elaborate?

If your mileage goes back to where it was, then it's the tune.

 

[maestromaestro]

If your mileage goes back to where it was, then it's the tune.

Well, that much I surmise. Certainly, easy to check this hypothesis. I’m just not expecting it to be the culprit- I don’t recall seeing any complaints about the loss of the fuel economy on the Dizzy tune.

 

[Clint Beastwood]

Well, that much I surmise. Certainly, easy to check this hypothesis. I’m just not expecting it to be the culprit- I don’t recall seeing any complaints about the loss of the fuel economy on the Dizzy tune.

well to be fair, most people tuning aren’t doing it or fuel economy

 

[maestromaestro]

well to be fair, most people tuning aren’t doing it or fuel economy

This is not being disputed. Having said this, there are 2 maps, one - an “economy” one. Dizzy’s are based off of the Cobb OTS, and I had much better MPGs with Cobb. Also, the AM tunes don’t really ding the economy. Before I had the flare kit put on, on the Cobb I’d get 32+on the highway.

 

[Clint Beastwood]

This is not being disputed. Having said this, there are 2 maps, one - an “economy” one. Dizzy’s are based off of the Cobb OTS, and I had much better MPGs with Cobb. Also, the AM tunes don’t really ding the economy. Before I had the flare kit put on, on the Cobb I’d get 32+on the highway.

I just meant I don’t think many people pay much attention to it post-tune so it might be hard to get responses. My own experience is invalid because I lived with 18mpg for a long time, figuring it was because I was only doing surface streets all the time

 

[maestromaestro]

. My own experience is invalid because I lived with 18mpg for a long time, figuring it was because I was only doing surface streets all the time

So - have you figured why it was so dismal, and if so - what was the cause of the problem/solution?

 

[Clint Beastwood]

So - have you figured why it was so dismal, and if so - what was the cause of the problem/solution?

Absurdly bad evap leak issue.
after fixing, I’m getting 24mpg on surface streets driving roughly the same and mid 30’s on the highway.

after replacing evap canister and some hose, car no longer feels like it wants to die after filling up with gas, too.

 

[JDG]

So, I had the tranny rebuilt, and, naturally, “while there”, ended with a new clutch (AP Racing) and flywheel and the Wavetrac LSD.
Also, switched to Dizzy Stage 2 tune (was running OTS Cobb Stage 3).

Now, what I see is that I went from about 28.5 mpgs to about 25 mpgs. Everything else - where I drive, how I drive, gas station/fuel that I use - is the same. Same tires, same pressure. The weather is pretty much the same as well.

Curious. Is there more friction/energy loss because of the LSD? The transmission is not native, but from a donor - otherwise, nothing else that comes to mind.

Suggestions?

How many miles have you driven with the new setup to come to the conclusion that you are now getting 25MPG?

I ask because I am guessing the change is a combination of the new tune, and the new modifications which are causing you to put your foot in it a bit more than you were previously (i.e. more throttle in the corners now that you have an LSD). The reality is that you probably changed too many variables to come to a real conclusion. I would swap back to the OTS tune for a few weeks and see what the change is.

 

[maestromaestro]

How many miles have you driven with the new setup to come to the conclusion that you are now getting 25MPG?

I ask because I am guessing the change is a combination of the new tune, and the new modifications which are causing you to put your foot in it a bit more than you were previously (i.e. more throttle in the corners now that you have an LSD). The reality is that you probably changed too many variables to come to a real conclusion. I would swap back to the OTS tune for a few weeks and see what the change is.

Been driving on it for a week. I am conscious about keeping my driving style the same. My daily commute is about 85 miles, and only one turn where I can engage in any kind of shenanigans if the road is clear. I'll switch back to OTS - that'd be a surprise if it turns out to be the reason....[emoji616]

 

[rallytaff]

I was getting about 28mpg before I had my lsd (WaveTrak) installed. Recently noticed that the mileage had dropped to 22mpg, but that was mainly around LA. Took a freeway trip, about 60 miles and the mileage increased to 24.5mpg. So slowly getting back up there.

 

[scooter123]

First, my Avatar is a Model T because I am a cheap old Geezer. As a result I do pay attention to my fuel mileage and actually adjust my driving to maximise my fuel mileage. Since I live smack in the Middle of Metro Detroit nearly all of my driving is surface streets and my average speed at each fill-up is normally between 22 and 25 mph. My target for fuel economy is 32 mpg. Yeah, don't always meet that goal because there are times when I will goose the FiST good and hard just because it gives me a good grin. As for highway miles, my sister lives in Lexington, VA and the rest of the extended family is in Charlotte, NC. Also have a family tradition of vacationing at Lake George, NY going back to 1966. So my Fiesta does get out for some long distance cruises. Highway mileage to Lake George generally averages about 37 mpg and the trips south average about 34 mpg. Of interest to me is the reason for the poor mileage going south isn't all the hills on the WV Turnpike, it's actually all the curves.

Anyhow I read what you guys are getting for fuel economy and I am actually SHOCKED. Folks, if you want to know the cause for your poor fuel economy I do believe that it's all those Tunes you've installed. Because while I have put in the full Mountune Induction kit and a Cobb 2 1/2 inch catback my car is still running on the original Fiesta ST tune. Currently I have stashed enough cash to fund either an Accessport with a MR230 tune or a new, prettier stock for my 12 gauge Beretta 686. After reading about FiST's only getting 24 mpg on some particular tune I'm thinking a new stock for the Beretta is the wise choice.

Just out of curiosity I'd like to ask maestromaestro to go back to the original Ford tune for his Fiesta and see how that effects his fuel economy. BTW, as a reference at 32 mph with cruise control ON in 5th gear and dead level smooth roadway I'll see 50-52 mpg on the mileage tattle-tail.

 

[M-Sport fan]

^^^How many rides have you, and family, taken on the 'Minnie Ha-Ha' in all of those years??

That must be one purdy, hand polished mahogany stock for you're scatter gun!

 

[green_henry]

First, my Avatar is a Model T because I am a cheap old Geezer. As a result I do pay attention to my fuel mileage and actually adjust my driving to maximise my fuel mileage. Since I live smack in the Middle of Metro Detroit nearly all of my driving is surface streets and my average speed at each fill-up is normally between 22 and 25 mph. My target for fuel economy is 32 mpg. Yeah, don't always meet that goal because there are times when I will goose the FiST good and hard just because it gives me a good grin. As for highway miles, my sister lives in Lexington, VA and the rest of the extended family is in Charlotte, NC. Also have a family tradition of vacationing at Lake George, NY going back to 1966. So my Fiesta does get out for some long distance cruises. Highway mileage to Lake George generally averages about 37 mpg and the trips south average about 34 mpg. Of interest to me is the reason for the poor mileage going south isn't all the hills on the WV Turnpike, it's actually all the curves.

Anyhow I read what you guys are getting for fuel economy and I am actually SHOCKED. Folks, if you want to know the cause for your poor fuel economy I do believe that it's all those Tunes you've installed. Because while I have put in the full Mountune Induction kit and a Cobb 2 1/2 inch catback my car is still running on the original Fiesta ST tune. Currently I have stashed enough cash to fund either an Accessport with a MR230 tune or a new, prettier stock for my 12 gauge Beretta 686. After reading about FiST's only getting 24 mpg on some particular tune I'm thinking a new stock for the Beretta is the wise choice.

Just out of curiosity I'd like to ask maestromaestro to go back to the original Ford tune for his Fiesta and see how that effects his fuel economy. BTW, as a reference at 32 mph with cruise control ON in 5th gear and dead level smooth roadway I'll see 50-52 mpg on the mileage tattle-tail.

I'm still averaging over 29 mpg on my Mountune tune, but I do not have an LSD. When I run E30, the average goes down, but I don't think I've seen below 28 mpg

 

[Erick_V]

I usually average around 25mpg on E30. Granted, my daily drive right now is mostly city and I never go above 50 unless I'm going across town. When I was driving a lot on highways I would cruise at 70-75 and I would barely get 300 miles out of a tank. My car would indicate almost 0 to empty when I would fill. I'm full bolt-ons and stratified tuned. Other than random accelerations I'm usually doing barely over the speed limit because I have enough reasons to be pulled over already lol

 

[maestromaestro]

Just out of curiosity I'd like to ask maestromaestro to go back to the original Ford tune for his Fiesta and see how that effects his fuel economy.

So - what I did do is to switch from the Dizzy Stage 2 tune back to the Cobb Stage 3 OTS one. Using the latter, in mostly highway driving I was getting 31-33 mpgs, if I didn’t indulge. After the WaveTrac LSD and the Dizzy tune, it dropped to 26 or slightly less, as I noted. So, back on the Cobb, I was seeing closer to 28.

Before you say “Aha!”, I suspect that the improvement is due to the new bits getting worked in. To see if I’m right, I will go back to Dizzy and see what develops. The irony is that I just moved, so my new commute went from 86 highway miles to about 12, all on surface streets. It’ll be awhile until I would get a chance to drive on a highway for an extended time.

My understanding of the tunes is that they optimize the “”fuel train” and remove some of the factory restrictions. So, the area under the curve is pretty much the same, it’s just that the initial slope is steeper - once you are cruising, tune or no tune, you are in the same spot on the graph. If you are doing the TOTD, then I’d expect a non-trivial difference between the factory and the aftermarket tune MPGs.