Serious Question Regarding ECU Tune

[tmcphail]

The GT has a hot wire type MAF sensor its not a vane door type as you describe. Its mounted in the exit tube of the air box and is below #8

This is the stock Base fuel table

To get fuller access to the calibration you would need the pro racer package. But you can make limited tune changes if you get the .XTR files from your tuner and download extreme tune from www.sctflash.com

But to echo what James has said your best bet is to find a good competent tuner and stick with them.


As for spark plug gap a bone stock GT can get away with the stock gap. But once you add power you need to shrink the gap or you will get spark blow out.

RWTD, that is a great series of posts, especially for a guy like me who doesn't know too much about EFI, but wants to learn :thumbsup . Sounds like the MAF sensor is more important than the MAP sensor in keeping the car tuned properly under open loop conditions. A few questions, if you don't mind:

1. What is the configuration of the MAF sensor on the GT? Is it a door that is opened further and further as more air is drawn into the engine, and the angle of the door opening is proportional to the mass air flow? Or is it something different?

2. Do you have the actual A/F values from the open loop fuel table that you posted for a stock GT?

3. I recently purchased an SCT programmer with a custom tune in it for the GT. If I interface this to my PC I assume that I will be able to see the fuel table that the custom tune is going to install?

4. Do you know the reason for the wide plug gap that Ford uses on the GT engine? I've run several supercharged engines on my dyno, and have never seen any benefit to running more than about .032" plug gap. In most cases where boost is higher than 7-8 psi, a wider plug gap will lose power. I don't understand why Ford uses a bigger gap, when reducing the gap down to .030" or so provides a clear performance advantage.

Thanks in advance for any comments!

 

[jaybnve]

Thanks Torrie, great info! :thumbsup

 

[RWTD]

Jay,

Torrie answered everything above just as I would.

Also, if you possibly didn't notice, I did post the stock OL fuel table of a stock GT in my post #13. Take a look here:

http://www.fordgtforum.com/forums/showpost.php?p=38462&postcount=13

Here it is again. You will see that I did the math for everyone and converted over the lambda values (on the bottom) to AFR values (on the top).

Also, in what you asked about the plug gap, a manufacturer wants to ensure that drivability, during what would be the majority of driving styles, is absolutely perfect. At times, when you gap plugs too low, there is the potential to experience drivability quirks, especially in the lower rpm range.

On the other hand, when you pointed out that power is generally gained, and there is a generally a clear performance advantage with a smaller gap, due to too large a gap potentially lowering power output with higher boost cars, that could be considered a similar situation to the cats issue I spoke of previously. Obviously there is a clearly a performance advantage to running 12.0 afr versus 10.0 or lower afr, but added power supposedly means more wear and tear, right? Well, that depends if you're Ford trying to save every last penny, or you're an educated owner who actually knows better than that BS, lol.

Okay, that's a bit on the far side, but it's very possible it plays a role somewhat too. :wink

Sincerely,

James

 

[jaybnve]

Thanks James, I just wasn't sure if the table you had originally posted was the stock one, or a modified version - Jay

 

[RWTD]

Thanks James, I just wasn't sure if the table you had originally posted was the stock one, or a modified version - Jay

Not a problem, sir. On a modded table, you will generally see 12.0 afr across the entire RPM range at 500 TP and above.

Sincerely,

James

 

[tmcphail]

Good ole .82 is generally my target ! Right on !

__________________
Mr. Torrie R. McPhail
2005 Black Twin Turbo Ford GT 1046rwhp / 892rwtq
2005 Silver Viper 610 rwhp / 760 rwtq
2006 Silver Jeep SRT-8 12.4@109.6

Not a problem, sir. On a modded table, you will generally see 12.0 afr across the entire RPM range at 500 TP and above.

Sincerely,

James