95 Gt engine issue

Crankyster_01

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I’ve posted on here previously with my car still having the same issue, I’ve been tinkering on it when time allows and have thrown some parts at it trying to fix it, known ford mechanic suggested trying to no avail. My issue when driving like granny the car is perfect, when getting on the throttle mildly aggressive it just kinda falls on its face but let off and be normal on throttle and it’s fine if you very slowly roll into the throttle and have a long time to get up to fast speed it seems ok, but anything over mild acceleration and it spits and spudders. I’ve tuned up with new plugs and ford racing wires, new fuel filter and air filter. Installed exhaust from headers back with off-road x pipe and Pyle cat back, due to no exhaust when buying car. I’ve just recently installed new mass air flow sensor and both o2 sensors. I’ve checked ccrm relay with new same issue. I’ve tried a new tfi thats mounted next to the air box same issue and tested mine like 15 times and found good.I checked timing with the spout out and found around 12degrees before tdc. I couldn’t say if the dizzy was good so I put a new one in it and assure all timing was correct same issue. I’ve checked fuel pressure and found 38 psi and 40 with regulator unplugged. I’ve done all I know and my buddies know of doing, so dropped it at the local ford guys shop and that’s why there’s a new mass air flow sensor and new o2 sensors on it, I think he dont want to work on it so I’m back to square one. I’ve checked codes it has the normal air codes due to removal of air pump and all, and the 556 code fuel pump primary circuit failure which I cannot figure out how it failed if I have correct fuel pressure. I need some help Im just before carb swap, but wish to remain fuel injected. Any direction or things to possiably check.
 

badass98svt

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Man, I know you said you changed it and tested your original, but I'd still say the TFI. Motorcraft TFI only, and even some of those have been faulty right out of the box lately.
 

95opal

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Code 556 is your answer.
Start by checking fuel pump wiring.
If you test FP under load id bet youd see a big drop off.
 
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white95

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Code 556 is your answer.
Start by checking fuel pump wiring.
If you test FP under load id bet youd see a big drop off.

This... Until you figure this out, you're pissing in the wind. So to speak.. Check the connectors at the tank for corrosion and/or poor connection. They're typically packed with die-electric grease to fight off moisture but these cars are old now. That stuff can break down over time. Report your findings. While you're at it, change the fuel filler to tank grommet and I'd pull the pump hanger and replace the in tank strainer. This is also a perfect time to install a mild fuel pump upgrade to facilitate future growth [up to 450 rwhp NA] and I recommend this one:

 

RAU03MACH

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I wanna say Sorenson
This was a few years back
They were having problems with them
It all started because of cost when ford was manufacturing them , places like autozone checkers were saying it was to expensive
You get what you pay for
 

Michael Plummer

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Back in 2002, there was a national class action in California, Howard v. Ford Motor Co., that reimbursed owners for failed ignition modules that occurred during the first 100,000 miles. Many other vehicles were affected but seeing this is an SN-95 forum it affected Mustangs built from 1984 to 94/95 Mustang/Capri HO (5.0L).

The Thick Film Ignition ("TFI") module, regulates the electrical current that fires the air-fuel mixture in each of the engine’s cylinders.

* A TFI module's "design life" was documented to be the lifetime of the vehicle because of the solid-state circuits used.
* A TFI's "service life" was discovered to fail when the module was subject to temperatures that exceeded approx. 254 degrees F.
* A "failing" TFI is when your vehicle stalls or dies at any time and restarts when the TFI module cools. Other symptoms can include bucking, and hesitation, and may experience other "driveability" symptoms that may provide you a warning that the TFI module is about to fail. It's important to note that this will happen at all loads and not when you try to go into WOT.......But it's easy enough to replace.

And despite what I posted above, I would still use a real Ford Motorcraft or Standard TFI module over anything else because the construction will be better over anything from the aftermarket.


I hope this helps
Michael Plummer
 
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RAU03MACH

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I do seem to remember this , but this was going on like 89
Or 90 and like you stated there was class actions going on
I know cost also had something to do with it
I think the company that took over it
I heard went bank rupt
 

Michael Plummer

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To the OP,
Others above mentioned checking fuel pressure under load and I agree that needs to be done to verify fuel pressure isn't dropping with an increase in load.

You mentioned you swapped out your distributor. I'm assuming your car wiring from the TFI and Distributor is fine but with no PIP signal from the distributor then your fault could be your Hall-Effect sensor inside your distributor. If it's not a distributor with an OEM or Ford Motorcraft stator simply upgrading your stator will be beneficial.

Normally, I don't post here that often but I'm leaving a link below that shows you the difference in quality between Ford Motorcraft parts and the aftermarket parts. Please do not buy Ford Motorcraft parts on Amazon. eBay is ok if the seller is a Ford Dealership.


I hope this helps
Michael Plummer
 
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Michael Plummer

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Q. I do seem to remember this , but this was going on like 89
A. Ford did everything in its power to not admit fault during the earlier years. But this was a safety issue because it left the vehicle without the use of power steering and brakes because the vehicles in question (many) would stall.
Q. I know cost also had something to do with it
A. Cost is everything in the automotive industry and I laugh every time I hear someone say "Ford should have done it this way". Mounting the TFI module on the distributor saved Ford millions.
Q. I heard went bank rupt
A. I don't know which company manufactured the TFI modules but I doubt the company went bankrupt. When it comes to electronics, Ford doesn't do cheap. Mounting the TFI in the hottest area in the engine bay was an engineering mistake. Moving them to the passenger fender helped according to Ford Engineers.

I hope that helps
Michael Plummer
 

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