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Discussion Starter #1
Anyone out there ever put their Mustang to diagnostic software? I have been having a bear of a time with an 01 GT which spark knocks like mad on tip in from 3000-4000 RPM. Still does it even after the Ford TSB spark knok reflash...

So me and my buddy started poking around with the autotap and here is what we found.

1. The spark knock TSB actually holds timing advance better than previous calibration...it would dial back to 7.5-10 degrees of advance prior now it holds 10-15 degrees during high load throttle applications.

2. The fuel pressure can drop to as low as 22PSI during tip-in situations. Ford spec on the 4.6L engine in an f-150 is 28-45 PSI if I read the service manual correctly. I assume the same calibration for the 4.6l 2v Mustang engine or thereabouts +/- 1-2 PSI. SO...

The 4.6L motor is a returnless system for fuel which can lead to problems (ever hear of the Powerstroke Diesel Cackle???)...this is the same principle. the ends of the fuel rails get starved due to shock or some other anomoly in the fuel delivery system at or near the injectors, causing starvation along the rail to the end cylinders. Could this be part of the problem? I think that 22PSI is a little low.

Also, the possiblity that the fuel pump isn't getting the voltage fast enough to bump the pressure? Keep in mind this is a bone stock GT with NO mods. What do ya think? Could this be the mystery issue with the spark knock or are radical drops in fuel pressure common in gasoline engines with returnless fuel systems?:confused:
 

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I have also considered fuel-starvation as contrbuting to my ping related problems. I have not quantified this w/diagnostics, but has anyone used or considered the new Steeda pump?

Steeda Autosports' new dual fuel pump system solves fuel starvation problems on 1999 and newer supercharged Mustangs. The stock fuel pump is not capable of supporting much more than 300 horsepower, and the old gerotor-style high-volume pumps don't last very long when subjected to the variable voltage used on the new "returnless" fuel systems. Steeda's new fuel system supports over 400 horsepower with two vane-style fuel pumps.

The 99/01 Cobras would be right at that 300HP threshold.
 

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Discussion Starter #3
fuel pressure where are the experts?

Cmon guys...no offense, but put down the quarter mile time slips and lets get this problem solved for everyone...Anyone in the baltimore, MD area that pings or doesn't ping is welcome to let me test thier fuel pressure through the auto tap...

Here;s why in my opinion the 99s don't ping like mad...the returnless didn't start till 2000 and up...:evil:
 

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Discussion Starter #4
fuel Pressure...

badbud: Those Steeda pumps are they expensive? This might be the fix we need...:joy:
 

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BadBud said:
I have also considered fuel-starvation as contrbuting to my ping related problems. I have not quantified this w/diagnostics, but has anyone used or considered the new Steeda pump?

Steeda Autosports' new dual fuel pump system solves fuel starvation problems on 1999 and newer supercharged Mustangs. The stock fuel pump is not capable of supporting much more than 300 horsepower, and the old gerotor-style high-volume pumps don't last very long when subjected to the variable voltage used on the new "returnless" fuel systems. Steeda's new fuel system supports over 400 horsepower with two vane-style fuel pumps.

The 99/01 Cobras would be right at that 300HP threshold.
Will the Steeda pump supply more pressure than the Walbro 255 supplied with the Vortech kit for my 2k1? Will it perform better than the Walbro with returnless system? I have some knock when under heavy boost. I will be talking to my tuner, but my tuner agrees that the 2001s are different than the earlier years. Still trying to figure out just what is different for tuning purposes.
 

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Discussion Starter #6
fuel pressure

chances are these two problems aren't related...your vortech is leaning out on top(your fuel curve needs fattened or you just need more fuel there), not like a stocker on tip in. Again...let's keep this thread going with relevant posts.:eek:
 

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Re: fuel Pressure...

skammer1 said:
badbud: Those Steeda pumps are they expensive? This might be the fix we need...:joy:
Steeda price is 399.95. The description says they are for s/c cars. But I quess they would work on N/A. :idunno:
 

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skammer1,
I think that 22 psi reported by the Autotap is realy low for fuel pressure and you may want to monitor the DIFFERENTIAL fuel pressure with a separate differential fuel pressure gauge if you can find one. You could make one as I did using the fuel rail pressure sensor from a 99+ engine.
I think that the PID system that is used, should be able to hold the differential pressure closer to the target value which could be around 40psi.
The variations in the fuel pressure could be caused by the program requrements, a software bug or a dud fuel rail sensor (they are around $40 ea), or even a maxed out EEC-V processor. It would requre a fuel pressure spec from Ford to tell if the sotware is mis-behaving, modifying the code ourselves is next to impossible.
PM me if you are interested in discussing this further.
 

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Discussion Starter #9
RESPONSE FROM FORD ON FUEL PRESSURE

Ford spec is 35-65 PSI for those that are interested...loaded or unloaded...The local dealer wants the car back...They called FoMoCo and were instructed to hook a fuel pressure gauge up to the vehicle and drive it....they are looking at fuel pressure, the sender, and also a possible catalyst problem according to the "GURUS" at FoMoCo. this will make the 5th visit for spark knock...it's getting old. but the car is still a blast.
:rolleyes:
 

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Wow tha fuel pressure spec is quite wide. Is it single ended i.e. measured from the fuel rail to air or from the fuel rail to the intake runner vaccum?
 

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Discussion Starter #11
BUMP

:lol: BUMP
 
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