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Lost MPGs

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#1
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

Senior Member
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#2
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.
 


OP
maestromaestro
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Thread Starter #5
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?
 


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#6
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.
 


OP
maestromaestro
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Thread Starter #7
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

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#8
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 :)
 


OP
maestromaestro
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Thread Starter #9
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

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#10
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
 


OP
maestromaestro
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Thread Starter #11
. 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

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#12
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

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Premium Account
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#13
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.
 


OP
maestromaestro
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Thread Starter #14
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....
 




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