Blended tune on stuck ECU ?

[Deric]

My 2003 Cobra is just about finished up and I've been getting more details from the tuner. So i have a few questions for you guys.

In my area, the best fuel we can get is 91 octane so I had the car tuned for that. I know, it's not ideal but it still put down 734 whp. I also requested a tune for VP MS109 for when I get the urge to go fast.

Anyway, on my previous build, I had a dial switch mounted in the center console and I simply turned it to whatever tune (1-10) I wanted with regards to the fuel I put in and which pulley I was running. My current builder just informed me that I no longer have to do that because both tunes are now a single blended tune on the stock ECU. There is no longer a need for a dial or any need to switch tunes. Simply switch fuels and swap the pulley and go. It is supposed to be smart enough to sense the change and make the adjustments on it's own.

I don't doubt their competency, but for my own piece of mind I would like to get some information on how this works. Maybe this method has been around and I just don't know about it, which is highly likely too. But it makes me a bit nervous to fill up with a different fuel and swap a pulley and call it good. Being a "blended tune" also raises the question of whether or not one of them is a compromise or "less safe."

Anybody have experience with this, or links to more information?

 

[cj428mach]

That is 100% not true. The ECM can't determine what kind of fuel is in the tank and make the necessary adjustments to WOT and timing.

If this would be possible running e85 would be so much easier to do.

 

[Deric]

Well the way it was explained to me was that when I swap pulleys, the computer will notice a few changes and run the tune for the fuel that is supposed to go with that particular pulley. They said the computer assumed I put the correct fuel in with the pulley swap because it can tell the difference between pulleys.

 

[decipha]

when an engine is calibrated correctly you can swap pulleys all day long and the ecu will compensate for it no problem so long as you dont exceed the flow limitations of the maf and the fuel system it will be perfectly fine no worries

race fuel usually has a slightly different stoichionetric ratio than pump gas, again, as long as the tuner setup the adaptive table to correctly apply correct fuel corrections to WOT, then the fuel will be fine, not to mention race gas can safely sustain a leaner burn so even if the tuner didnt correctly reference learned trims at WOT the variance in stoichiometric shouldnt be an issue, to further that, most pump gas is e10 and most race fuels have a stoich higher than that so its likely youll be a touch richer with race gas anywho

as for spark, if the tune is calibrated correctly then the same applies as fuel

the only variance is attempting to run high boost with pump gas, if you told the tuner you will only run the smaller pulley (more boost) with race gas then the tuner can safely command more spark at a higher boost if he setup the spark table correctly for it, unless the spark works out about the same then that wouldnt matter

how much boost are you making on pump gas and how much boost on the smaller pulley?

IT IS POSSIBLE for the ecu to be able to swap tunes AUTOMATICALLY between pump gas and E85 with no user input required, it requires that you have a wideband and a moates quarterhorse though and the tuner has to write their own code to have the QH swap tunes based on the wideband feedback

info in link below

http://info.efidynotuning.com/fuel101.htm

 

[MalcolmV8]

Deric,

You're double posting the same thing in multiple forums. Here's what I responded in the other thread although Decipha just explained it better than me.

Our ECUs have no way of sensing or assuming octane. My guess is your tuner dialed the car in with the smaller pulley and told you it's safe to run the larger pulley too. That much would be correct because the larger pulley will just use less air and not go as far up into the MAF curve.
Your timing tables would be static though. I suppose your tuner may have looked at load with the larger pulley and set up timing accordingly and then in the timing table for loads above that increased timing knowing you'll be on a smaller pulley to get there with a better fuel. I've never personally done that but it sounds like it would work.
In any case the ECU's not sensing or changing anything but possibly doing what I just described.

 

[Deric]

Yeah I posted it here and it wasn't showing up on my phone. I decided it would get more targeted traffic in the cobra forums. Now I have two threads. Oops.

I'll look into all this when I get home later tonight. Thanks for the input guys

 

[15PSI]

No. That is incorrect. The tunes for the different fuels are independent of each other. The ECU cannot determine the fuel octane and must have a separate tune for each different fuel.