Re-flash to run lower octane fuel?

M

Mike Poore

Crabmonster
The lease is up on Barb's '05 Aviator in September, and we'd like to buy it and give it to the kids. Only thing is, it has the 4.6 DOHC motor, I think exactly the same one as the '04MM, and requires 91+ octane fuel. Can we buy a chip to re-flash the 'puter allowing it to run on 87?

It's a wonderful vehicle, and would be good, safe transportation for them and the three children; but sucking up 93 octane gas at 15MPG could be a deal breaking issue.
 
And take all the fun out of it?:D
Of course you can, you need the ECM code, and someone who can burn a chip or flash the ECM.
A newer hand held tuner would give some adjustibility as well.
 
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Bradley G said:
And take all the fun out of it?:D
Of course you can, you need the ECM code, and someone who can burn a chip or flash the ECM.
A newer hand held tuner would give some adjustibility as well.
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I was hoping it was gonna be that easy. I guess a hand heald tuner would be the way to go, since John has a Mach 1 with the same motor. It would be a way cool birthday gift ....the Aviator and the tuner. :D

Thanks buddy. :high5:
 
Dennis tuned our Aviator. And just as with the Marauder, it isn't wise, nor is it any more efficient to de-tune the car for cheap gas.For what little saving one would get saving 10-15 cent a gallon over 25 gallons, it isn't worth the sheer amount of timing that would be pulled from the motor.
 
Mike Poore said:
The lease is up on Barb's '05 Aviator in September, and we'd like to buy it and give it to the kids. Only thing is, it has the 4.6 DOHC motor, I think exactly the same one as the '04MM, and requires 91+ octane fuel. Can we buy a chip to re-flash the 'puter allowing it to run on 87?

It's a wonderful vehicle, and would be good, safe transportation for them and the three children; but sucking up 93 octane gas at 15MPG could be a deal breaking issue.
Click to expand...


I could make a lower spark and adjust EGR and improve it some so you could run 87
 
CRUZTAKER said:
Dennis tuned our Aviator. And just as with the Marauder, it isn't wise, nor is it any more efficient to de-tune the car for cheap gas.For what little saving one would get saving 10-15 cent a gallon over 25 gallons, it isn't worth the sheer amount of timing that would be pulled from the motor.
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Barry, it's 30 cents a gallon difference, here. John and Megan won't care how fast they get there, but need the room and safety the Aviator will provide my grandchildren.

I've gotten the answer I need, thank you Brad & Dennis, and think it might be useful and entertaining to discuss the fine points of changing the tune, for reasons others might consider. :)
 
Guess it's a matter of perspective. 30 cents per gallon on a 25 gallon fill is $7.50, but
weighed against a $100 fill-up, it's kinda chump change. Or, to look at it another way,
the cost savings would give you the equivalent of about 1.75 gallons per fill up. At 15MPG,
that's only an extra 26 miles per tank, -IF- the detuning doesn't cost you any efficiency.
And that's a very big 'IF'.

And, of course, you're not gonna get that tuner for free.

Out here, Chevron premium is usually 20 cents more than regular. I'm not willing to
accept the potential risk for <5% gain, but hey, if it turns out well for you, I'll be
happy to change my tune, so to speak... :)
 
JACook said:
Guess it's a matter of perspective. 30 cents per gallon on a 25 gallon fill is $7.50, but
weighed against a $100 fill-up, it's kinda chump change. Or, to look at it another way,
the cost savings would give you the equivalent of about 1.75 gallons per fill up. At 15MPG,
that's only an extra 26 miles per tank, -IF- the detuning doesn't cost you any efficiency.
And that's a very big 'IF'.

And, of course, you're not gonna get that tuner for free.

Out here, Chevron premium is usually 20 cents more than regular. I'm not willing to
accept the potential risk for <5% gain, but hey, if it turns out well for you, I'll be
happy to change my tune, so to speak... :)
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Bingo.

Jessica wants to bak it down as well...that why we are looking into a Suburu AWD waggon rather than detuning a big V8 SUV.
 
CRUZTAKER said:
Bingo.

Jessica wants to bak it down as well...that why we are looking into a Suburu AWD waggon rather than detuning a big V8 SUV.
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Those questions make it an interesting discussion, Barry.

Bottom line: will de-tuning it negate any gains in cost per gallon of fuel. What is the break even point; and are we talking about genuine savings or just making us feel good. :dunno:

Charlie (bluerauder) is good at these cost analysis issues, and I think, Dennis has those data.

It may be an interesting exercise for all of us to consider, though. I can see, however, the wisdom of going with a hand-held device, as Brad suggests, rather than burning a chip, if the initial cost doesn't negate any savings over the long run.
 
You have the perfect test.
Check you mileage before and after the de-tune and the question will be answered once and for all!!
 
You can always pull timing and lose major HP, and it will run fine but why. The muscle car guys still find that you lose a lot more HP building an engine w/ too high compression, and having to back a ton of timing out to not detonate, than you would lose building the engine w/ appropriate compression ratio and running aggresive timing.

In this case it is reverse engineering of the wrong kind. I'm sure someone with a crown vic would love to trade engines with you.
 
Mike Poore said:
Charlie (bluerauder) is good at these cost analysis issues, and I think, Dennis has those data.
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I ran some numbers for Mike and sent a PM. Here's a summary ---

Mike's proposed course of action results in a savings of only $200-$300 per year on a fuel bill that is about $4000. Not a big savings in my opinion. That's only $3.85 to $5.77 a week. Less than a typical lunch.

It would take 16-24 months to offset the cost of a typical tuner at this rate.

However, if the tune results in a drop of just 1 MPG to 14 MPG, that savings is nearly completely offset and the net savings is only $19.00 for the year.

The loss of any more MPGs than that (e.g. down to 13.9 MPG) would cost more than the savings and it would have been better to keep 15 MPG with 93 Octane.

On economics alone, this doesn't appear to be a reasonable solution. Factor in potential damage to the 4.6L DOHC and it is a "No Brainer" IMHO. I wouldn't do it.
 
First, lets understand and all agree that you can run regular grade gas without engine damage - if you tune for it. No one here thinks of a Marauder as an economy car, but there are things you can do to boost fuel mileage a little. My father insisted on putting regular into his Marauder and it never detonated, but I looked at how active the knock sensor was in pulling timing, so I just retuned it for 89. The car is not as fast as it was and I do not know if he is really saving anything in the end, but still, you can do it. Aside from detuning to run on regular gas - which may or may not actually save you money, there are other things I have done and you can do to increase fuel mileage with minimal impact on performance.

Mitch
 
With gasoline costing over $4.00 a gallon,
you think that the 20 cents in savings is worth wrecking the engine ???

You cannot tune the Marauder engine for 87 octane.
There are physics within the engine that require 91 octane
and they cannot be changed without some physical change
to the engnie itself.

Tuning for spark timing and EGR will only delay the inevitable **BOOM**.
 
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Stangracer89 said:
No. 10:1 compression. It is not a mileage or cost issue. It is a detonation issue.
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The compression is not the problem.
There are plenty of high compression engines running 87 octane fuel.
The problem is the design of the combustion chamber.
The flat area where the piston just clears the head is called the quench area.
When an engine is deisgned using quench pistons, like ours,
they develop maximum compression and have very close tolerances to the head surface.
This design tends to produce detonation with lower octane fuels.
This is why there is a need to run 91 octane or higher.
Swap out your pistons for non-quench pistons and you lower the quench area,
lower the compression and can now run a lower octane fuel.

Now you will need to retune to get back all of the lost horsepower.
 
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