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Discussion Starter · #1 ·
Hello,

Let me start by saying that I am new to the 5.0 EFI world. I'm building a 1994 Mustang GT for bracket racing and maybe stock eliminator later on. The engine is new and it has been lightly modified (i'll get into the details shortly). The car has had lots of stuff removed like the power steering, power brakes, heating & AC, and all the emissions control stuff. I've installed a FMS T5 that was set up by G Force for drag racing, a Centerforce clutch, and a McCloud scatter sheild. I haven't installed them yet, but I am putting in a Strange rear axle package with a 4.88 ration too.

So the engine is basically stock (as per NHRA stock class rules). Bullet ground the cam and the heads have Manley springs and retainers for the agressive lobe patterm we chose. It also has 3/8" Manton push rods. I installed 24lb injectors and a 75mm MAF calibrated for them. I've also installed a MSD 6A programmable ignition with the stock distributor.

The car starts and I can get it to idle by opening the throttle body using the idle adjustment screw. It wants to idle around 1100 rpm with the Bullet cam. I have 15* of static timing in it. When I open the throttle from an idle, the engine hesitates then tries to rev, but it sounds really flat like it's being held back. The engine is very rich judging just from the exhaust smell.

Now that I have it all together, I'm trying to sort out the problems. As I said at the start, I'm new to these EFI configurations so I was hoping to get some tips on how to start diagnosing it's problems. A couple of this come to mind. First, I noticed that the fuel regulator is vacuum operated. I suspect the cam I'm running has killed a lot of manifold vacuum due to the big duration. Do I need to use a different regulator on my set up? Also, Are there any compatibility issues between the MSD 6A and the stock distributor? Lastly, I want to put a fuel pressure gauge on the car. What's a good setup for this?

Thanks in advance for the advise,
Cliff Wright

PS: I've been running carbureted stuff for years (see Hemi Ford.com). But this is the first EFI project I've undertaken.
 

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Unplug your SPOUT connector and set your base timing. Once you have set it to 14 or 15 degrees then plug the spout connector in and try to get the car to idle at 750rpm and see what the timing is.

You picked one of the worst EFI models to begin your journey in the EFI world I hate to say ha. These computers require alot of tuning and tweeking and being OBD I it is not easy to properly tweek and tune it without a Stand alone ECM ($$$$) or a piggyback style chip like a quarter horse (highly recommend).

Asside from your vacuum issue (which can be corrected with an electric vacuum pump same idea if you were to run a supercharged setup). But my concern is your ignition timing. The spark curve the T4M0 computer(the one in your car) is adjusted by load values which is how most all efi vehicles adjust ignition timing. But what makes these cars unique is the load value is based ONLY on your MAF reading and the stock 5.0L programming. So if you are any more efficient then stock 5.0 (pulling in more air) your computer is going to think your demanding load on the engine and advance the timing to the point where it will not run. Things like cams, cylinder heads anything that makes your 5.0 have better volumetric efficientcy then stock will alter your spark curve.

So if you had the ignition timing adjusted with the spout connector plugged in, chances are at 6500rpm your still going to be maxed out at 15 degrees advanced... The pcm can only adjust timing soo much on these vehicles. My assumption is your already at max. Making your throttle response poor because when you open that throttle body the pcm notices the rpms and the tps values and sees that your putting demand on the engine but cannot advance the timing anymore to compensate.

I can ramble on and on But consider a Quarter Horse manufacutered by Moates. It plugs into your J3 port like a regular chip but allows you to adjust any parameters within the PCM and then some. The only problem with quarterhorse is you have to find out how to gety our hands on the software... Most dyno places can get ahold of the software because there licensed but for us backyarders its not very easy to get a hold of it.. from my experiance anyways some may argue that..

I also forgot to mention that the T4M0 computer pulls ignition timing during shifts. If your car came stock with a standard its not nearly as bad as if it was stock with an automatic... The theory behind that is to manipulate the engine to produce less power during shifts this means ford doesnt have to warrant as many AODE's and T5 transmissions as they had to for the foxbody mustangs!

Hope I could help.
 

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I want to correct myself.

They are not the worst computers due to them having a 3x faster processor then the foxbodys.

But if you dont understand how there programming they can be a pain in the ass!!!!!
 

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Discussion Starter · #4 ·
Thanks for the info. I'm not opposed to spending a little dough to get this right, so if upgrading the EMS is what I need then so be it. Another NHRA stock class racer told me that he uses a piggy-back unit from Anderson Performance called a PMS by EFI Systems. They even offer it with a data recorder... nice! Anyone familiar with these?

Another question: What is the purpose of the vacuum controlled fuel regulator? Is this just to make the car more manageable at low speed/high vacuum operation. When I look at other competition EFI setups, they look like they are running a constant pressure system with a bypass style regulator to set the pressure. Since this is a race car, I'm not that concerned about low speed drivability.

Cliff
 

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Like I suggested Moates makes a piggy back system called the Quater Horse if you do some reasearch into it and somehow manage to get your own software (you need a licence # maybe whoever is a licenced dyno tuner you know can get one for you) then you can play with all the parameters, save different tunes its an awesome thing to have.

As far as the FPR I honestly have no answer for you. I can sit here and play guessing games but yeah, I have no honest knowledgeable answer.
 
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