Leaner Fuel Mixture


PHXGT

GT Owner
Mark II Lifetime
Sep 11, 2005
369
Phoenix, AZ
Has there been anything written with any positive results on leaning out the fuel mapping? I hear from Detroit that the GT is set at the factory with a very very rich fuel map. How dangerous, how is it done, is it worth the risk?
 

barondw

GT Owner
Sep 8, 2005
1,109
First some engines are design to run on a richer mixture and other are designed to run on a leaner mix. Typically a manufacturer develops a setting that will provide good performance, economy, and keep warranty claims to a minimum. So there is the potential to improve performance by changing the map or re-flashing the computer.

Typically this can be done in one of several ways. Others may suggest even additional methods. These methods include buying a device like an EEC-Tuner which was developed for older Ford engines( I don’t believe any are available for the GT), a piggy-back computer which in effect sits on-top of the cars computer and can be reprogrammed (Perfect Power makes these systems and again I don’t believe they are available for the GT), buying a chip which has a new program (Again don’t believe any are available for the GT), using the Diablo Predator which comes with a new program (I have been told they have a file available), or finding some one who has a new map file and can explain how to download to the car. Another option is waiting to see if SVT will offer an upgraded supercharger, which will be covered by warranty this has been rumored from day 1. They have tested several units but none meet all of FoMoCo’s criteria for a production vehicle.

Typically all manufacturers void a vehicle's warranty if they know the computer has been re-flashed or the car has been chipped. Also there is substantial risk IMO to the engine and the crate cost is $ 27,000 plus installation. You may want to think twice before doing a re-flash or chip. I have not done it because of the potential economic downside.

Also consider that the GT is a low volume car with a relatively tiny portion of owners who want to increase the power. Thus can we really expect many vendors to offer items if there is no mass market. Now if the chip or whatever could be used on the then to be released Shelby Cobra Mustang 500GT maybe it could happen.

Yes a pre-production John Coletti tricked GT did 10.185 ET at Englishtown. That car had a smaller pulley, gutted cats, and re-flashed computer and was set-up for the quarter-mile. I do not know if they changed the gearbox or rear-end ratios.
:cheers
 

PHXGT

GT Owner
Mark II Lifetime
Sep 11, 2005
369
Phoenix, AZ
Great info. Thanks!!! Sounds like the best advice is to wait and watch.
 

dbk

The Favor Factory™
Staff member
Le Mans 2010 Supporter
Jul 30, 2005
15,187
Metro Detroit
Does anyone even know what the A/F is? I'm sure once you ran it on the dyno with a wideband, it'd be clear if it was excessively rich for safety. Thereafter, I don't know why tuning the car would be any harder than tuning any other 5.4 DOHC Ford...

I believe John Hennessy is working on one now. I recall someone posting somewhere that JH was doing all the work for free on a friends car to see what the possibilities were.
 

barondw

GT Owner
Sep 8, 2005
1,109
DBK said:
Does anyone even know what the A/F is? I'm sure once you ran it on the dyno with a wideband, it'd be clear if it was excessively rich for safety. Thereafter, I don't know why tuning the car would be any harder than tuning any other 5.4 DOHC Ford...

I believe John Hennessy is working on one now. I recall someone posting somewhere that JH was doing all the work for free on a friends car to see what the possibilities were.


It ran about 11:1 - 12: 1 depending upon run. This was with a wideband.

You need to have a bung installed and create an access hole through the engine pan with a removal flap. Otherwise you need to completely remove the rear most belly pan which requires the removal of the adjacnet pan in order to gain access. Its a real pain and can involve double jacking and lowering depending on what type of lift you utilize. That's why an oil change takes about 2 hours.

Access can be through a rubber plug or and metal cover screwed into the belly pan. We did the latter.
 

dbk

The Favor Factory™
Staff member
Le Mans 2010 Supporter
Jul 30, 2005
15,187
Metro Detroit
Interesting. That's not as obscenely rich as I've seen on some stock cars, but 12.1 still has alot of wiggle room. Also very interesting as far as the access. Sounds like a major hassle.
 

barondw

GT Owner
Sep 8, 2005
1,109
DBK said:
Interesting. That's not as obscenely rich as I've seen on some stock cars, but 12.1 still has alot of wiggle room. Also very interesting as far as the access. Sounds like a major hassle.

Access from underneath is a real hassle. Remember that the whole underbody is encased in a belly pan from front to rear. Anything that needs to be done requires the removal of the belly pan panels. Since the panels are held on with screws carry some extra because they will get lost and the dealer will strip the screw heads.

Also find out where the jacking points are in case you get a flat and have to have it repaired on the road to prevent them jacking in the wrong place and damaging the underbody.


:cheers
 

barondw

GT Owner
Sep 8, 2005
1,109
PHXGT said:
Has there been anything written with any positive results on leaning out the fuel mapping? I hear from Detroit that the GT is set at the factory with a very very rich fuel map. How dangerous, how is it done, is it worth the risk?

I have spoken with several tuners in my area who claim to have the required software to reflash the computer. Some even have software to allow you to adjust tuning depending upon different driving conditions, drag, road course, street, etc.

I personally will not recommend any dealer as the potential issues with warranty are too big for me to do a reflash. But I am sure if you check around where you live there are folks with the software who can do the work.
 

50 BMG

Well-known member
Aug 3, 2005
559
AZ
PHXGT-

If you're serious about doing this, the first people I would call in Phoenix are SVC motorsports. I took my 04 cobra in there for -a lot- of work and it came back in the same flawless condition as when I dropped it off and it runs strong as hell. In fact it's one of the fastest off the bottle eaton cobras in the country, with the tune never exceeding an A/F ratio above 11.5 The tuner down there knows his shit.

SVC does a lot of tuning on forced induction exotics and specialize in Ford single and dual OHC engines. They're conservative with their tunes, espcially on supercharged and turbocharged cars.

Their installs are top quality and they stand behind their products/work 100%. Not only that, they do not let a car leave the shop unless it is perfect while doing everything to manufacturer specs where applicable. One of the owners (Rob) does most of the nitty gritty work and all of the tuning. He is obsessive complusive about letting customer cars go in a perfect state.

The only problem with the place is that they take a lot of time on their projects to make sure everything is correct.

480-998-8885
Ask for Dean
 

PHXGT

GT Owner
Mark II Lifetime
Sep 11, 2005
369
Phoenix, AZ
WOW Thanks for the great info.
 

barondw

GT Owner
Sep 8, 2005
1,109
PHXGT

Ask them for a dyno before and after. Also ask what is their expectation for HP AND Torque gain. Some of the edits/flashes do not give as much of a gain as the owner think they will get.

Last have they done it on any other GT, if not how do they know what the increase will be?
 

PHXGT

GT Owner
Mark II Lifetime
Sep 11, 2005
369
Phoenix, AZ
Thanks for the insight.