Home: Mustang Tech: Maintenance and Tune Up: EFI Tuning part 1
EFI Tuning part 1


We here the words "tune it" lots of times, but what's really a good tune-up for your stang? the most common answer is "change filters, oils and plugs", and that's what most shops and dealers will do.

In this article we want to show you how to perform a HI-PERFORMANCE TUNE UP, that will leave your car in top shape.

So what's involved in this kind of tune up?

  1. Cleaning engine !
  2. K&N Filter cleaning or replacing stock with K&N
  3. Spark Plugs, plug wires and Distributor cap and rotor with brass terminals.
  4. New lubricants, synthetics if you can afford it for ENGINE and TRANNY
  5. Flushing radiator and adding 180 "balanced" thermostat (more on the "balanced" later)
  6. Setting timing
  7. Cleaning TB, Intake and Carbon deposits
  8. New Brake fluid and bleeding (new pads maybe?)
  9. Running KOEO an KOER EEC tests
  10. Final Comments
  11. PART 2


Check PART 2 Sensors

1. OK, so lets start with cleaning the engine compartment, one really easy way to clean the engine is to use "simple green" or equivalent type of de greaser. We encourage you to use only "environmentally safe" stuff.

First you have to cover some stuff that might be damaged by water such as the wiring harness connectors and that K&N you have exposed under the hood (in some cases). Use a plastic bag for the K&N and aluminum foil to wrap the connectors. Don't worry about the distributor since you will change wires and cap later.
Apply the cleaning solution liberally to the engine using a sponge, work your way under all small crevices, accessories etc, etc. Also apply to the hood insulation, this sucker gets pretty dirty.
Now wait for 15-20 minutes for the stuff to start working, then use a hose to wash off all that dirt. Start the engine and let it idle for 10 minutes so the water evaporates. Use an old T-shirt to completely dry the engine. Aluminum parts will stain if you leave water on them.

2. If you have a K&N, this is the time to clean it, but use only the K&N cleaning and oiling products. If you have a stock air filter then get a K&N !!

3. Next is changing your plugs, wires and distributor cap & rotor (5.0s), start by changing the cap and rotor, replace by first swapping the OLD wires to the new cap, check that the wires are replaced in the same order, the cap has a mark for #1 piston. Now loosen the old cap and replace the rotor, make sure there's no water in there.

Now change the plugs, this is the "fun part" cause it is not that easy to remove the plug wire boots from the plugs. Use mechanics or leather gloves to do this, your hands will thank you. Start by calibrating your new plugs, we recommend you to use AUTOLITES #24 on 5.0s, stay away from "sh*tfires" ouch..mean SplitFires and similar types of plugs, also stay away from platinum's. If you cant find Autolites use Motorcraft's. Gap them to .052
4.6 and DOHC's should use platinum's, buy Bosch or NGK's.

Btw, don't remove your wires if you don't know the firing order, just place the old wire boots over the new plugs without pushing them all the way.

Change the plug wires now, do it one by one until all are replaced and don't forget the coil wire. Here we recommend to try the FMS 9mm, Accel 300 or LiveWires. Or choose the brand of your choice. Buying a thermo insulation for your wires and boots is a wise thing to do if you have Equal length headers and if you want your wires to last longer.

After this step, start your engine to check for possible arcing on the wires. Make sure the boots are all the way down on the plugs.

4. Oil change time.

This you can do at home with simple tools, an oil filter removal wrench and a large pan to drain the old oil. Our recommendation is to have your oil changed at a place where they have the tools and oil recycling facilities. It takes 30 minutes and it is not that expensive. Our recommendation is to go with Synthetic oils, they last longer and have better heat dissipation qualities. Try Mobil 1, we have had great results with it. Just stay away from PTF (Teflon) loaded oils, such as Slick-50, they can clog your filter and oil passages. For the filter get a MOTORCRAFT one, stay away from FRAM and the cheap ones. Not all filters are alike.

5. Flush your radiator and change your Thermostat, Here start by removing the Coolant drain plugs on the block and opening the radiator flush (on front lower passenger side).

Remove the thermostat by loosening the 2 bolts and removing the water pump and radiator hoses that connect to the thermostat housing. Remove all the gasket material at the lower intake and thermostat housing, you can use a sharp knife or exacto knife to do this.

Install the thermostat housing without a thermostat or gasket, place the block drain plugs in place, re-attach the hoses and fill the system with water using a hose. Start the engine with the water running, open the radiator drain. This will flush most of the gunk out of the system. Let it run for a few minutes and Drain the system completely again.

Now install your new thermostat and new gasket. But first some important notes about Thermostats:

  • Not all thermostats are created equal, the "cheap" ones are not a good choice since they will not open and close exactly at the same temperature and water pressure, you best bet here is to buy a "BALANCED" thermostat such as the ones sold by Mr. Gasket, this thermostats have a special construction that makes them open and close exactly at the same temperature regardless of pressure.
    They will also not get stuck, we have seen lots of new cheap thermostats do this after a few days or even hours.

Make sure you place that thermostat in the right direction, the spring side goes to the lower intake. Good thermostats have an arrow pointing which side goes to the radiator.

Now assemble everything back, put the block drain plugs in place and close the drain on the radiator, start the engine and fill the radiator with a mix of coolant and water, here just a few notes, if you are on a HOT location, use a 70% water 30% coolant mix, on colder areas increase the coolant to a 50-50 mix. Also on hot places use "Water Wetter" for added cooling efficiency, this stuff can lower the temp as much as 10-15 degrees.

Start the engine with the radiator cap removed, add water/coolant mix until it is completely full and you don't see any more air bubbles. Also fill the drain bottle to the top. Take the car for a spin for a few minutes and check coolant again. The level on the drain bottle might go down until all the bubbles are out of the system. Re-check the coolant level for the next couple of days and inspect for possible leaks at the thermostat housing gasket, if so re-tighten the bolts a bit, but not much as you can break the housing.

6. Setting your timing is important from a performance stand point, when you increase timing a bit, you improve the combustion efficiency. Setting timing can only be accomplished MANUALY on 5.0 engines. 4.6 owners should either get a chip or buy a special timing wheel to adjust it. We don't recall the name of this piece but we will look for it and let you know.

An increase in timing can make your car DETONATE or ping, this is caused by a larger need of fuel by the engine or a need for higher octane fuel. Check our complete explanation here.

Your timing should be increased to a point where you don't hear detonation and where your car makes the most power. Since not all cars are created equal some respond better to advance and some others don't. High altitude Calibrated EEC's on 5.0s starting with serial #F4AE, are more prone to detonation that the series #F4ZF which are low altitude. Above your DOOR TAG you might find another small tag that says CALIBRATION CODE, with 2 numbers, the lower one is your PCM series number. If you cant find it there then you can find the EEC at the passenger side kick-panel.

Sout connector (Click for larger image)With the engine OFF, remove the TIMING PLUG or SPOUT connector that is found on the passenger side close to the Air box. The plug is most of the times a GRAY fuse like thing that's inside a connector on a wiring harness. Now loosen the distributor bolt so that the distributor can move by hand. The bolt shouldn't be too loose as to allow the distributor to move alone.

To set the timing you will need a TIMING LIGHT, if you don't have one then buy, rent, or ask your neighbor for one (even if he has a Ch*vy).

Place the timing light "pick-up" at the #1 plug wire, the #1 is marked on the distributor cap. Connect the (+) and (-) terminals to the battery if the timing light is not a battery operated one.

Now locate the crank balancer wheel, it has marks to tell you advance and retard, if they are not visible try painting them with white paint from 0 to 15 degrees.

Start the engine, (without the spout connector unplugged) point the timing light to the wheel and move your dist clockwise to advance the timing, start at 15 degrees and stop. Stop the engine and put back the SPOUT.
Test your car, drive around for awhile. If you hear detonation or pinging retard 1 degree until it stops. Also try using higher octane Gas (92-93) to stop the detonation. Make sure you disconnect the battery to clear all stored memory tables in the EEC.

7. The Throttle body and Intake can get pretty dirty after a while, the oil and gunk deposits in them can reduce your pony's performance. Also after lots of traffic driving your heads and valves might get covered with Carbon deposits that can cause PRE-IGNITION, which is as bad as detonation.

To clean it all there are a few things you can do, either remove the intake and heads to clean them OR the EASY WAY. use Carb Cleaner or BRAKE FLUID to clean them. If you use Carb cleaner just make sure it is O2 sensor-safe. Brake fluid is.

This procedure is for 5.0 engines only, 4.6 should not try this.

Now disconnect the hose that runs from the passenger side valve cover on the OIL FILL TUBE to the Throttle body hose. Disconnect at the valve cover side.

Start your engine and either SPRAY the carb cleaner into the hose or Immerse the hose in the brake fluid bottle. Do this 1 second at a time and rev the engine a bit if it starts to stall, repeat the procedure until you are half way on the cleaner or brake fluid.

You will see lots of smoke from the exhaust..this is normal and a sign that the cleaner is working.Take the car for a ride and repeat the procedure the next day.

8. Brake fluid replacement and bleeding is something you should do at least every year. Brake fluid absorbs moisture from the exterior, that moisture can create rust inside the brake system making it less efficient. To drain the system you have 2 choices, one is to get your car to specialized shop that can drain it without leaving bubbles in the ABS (if so equipped). This is hard to do.

You second choice is do it at home and try to replace most of the fluid with new one.

Start by getting some decent synthetic fluid, 3 or 4 small bottles is all you need, we here also recommend Mobil or Motorcraft. The synthetic fluid absorbs less moisture and can withstand higher temperatures, a good thing if you race your car.

For this procedure you will need the help of a friend to press the brake pedal while you open the bleeder valves on the brakes. You will also need to place a rubber hose on the bleeder at the brake to pour the old fluid inside a used bottle.

Start with the passenger side REAR caliper, have someone press the brake (or use a jack against the seat and brake.) and open the bleeder slowly until fluid stops leaking, then close it. Ask your buddy to remove his foot from the brake pedal or remove the jack. Repeat this procedure 5 times. Now check the fluid level and add NEW FLUID to the reservoir. Go to the drivers side rear wheel, repeat the process. Do the same at the front, go to the passenger side first then do the drivers side. Don't forget to fill the brake fluid reservoir tank before it gets empty!!!.

Take the car for a spin at SLOW SPEED, and test the brakes several times, increase your speed as you get confident that everything is ok, hit the brakes harder and harder each time. If they feel very "mushy" or soft, try bleeding them again, probably a bit of air got into them.

9. A KOEO and KOER test will tell you a lot about the health of your car. Even if you haven't seen the CHECK ENGINE light Flash. And it is a procedure that is easy to perform with just a piece of wire or a digital voltmeter.

The complete EEC test procedure can be found here.

After performing your tune up and checking your EEC for stored codes it is a wise idea to reset the EEC stored memory tables. When the tables get erased the EEC will start to relearn its fuel and air strategies which will make you car perform better.

To erase the memory all you have to do is disconnect the battery for 20 minutes.


After performing this HI-PERF TUNE-UP your car will feel a lot stronger, your MPG will increase and your stang will be happy !

This complete tune-up should be performed once a year with the exception of some stuff like lubricants, filters and plugs that should be replaced every 3,000 miles.

Your wires should also last more than a year..so don't go replace them every year, but probably every 2-3 years.

Now..get out of here and enjoy your car!



Article by: GTRaptor Profile | E-Mail

We hear the words "tune it" lots of times, but what's really a good tune-up for your stang? the most common answer is "change filters, oils and plugs", and thats what most shops and dealers will do.

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