Mustangs List FAQ - Part 1

"Late Model" Mustangs FAQ Table of Contents and Index
Last modified 7/9/98

=========================================================================
Mustangs FAQ Table of Contents
=========================================================================

Part 1 [current revision: 1.3]
        1) Quick glossary of terms
        2) What manuals and publications are good sources of information?
        3) Ford addresses and phone numbers
        4) What modifications should I make to my car?
        5) What modifications can be made to my car for little or no money?

Part 2 [current revision: 1.1]
        1) Door tag info ("How do I know what XXXX my car came with?")
        2) What effect will a different axle ratio have on my car?

Part 3 [current revision: 1.2]
	1) Information on the factory system
	2) Aftermarket stereo installation concerns
	3) Some installation examples

Part 4 [current revision: 1.0]
	1) Failures/diagnoses
	2) Water pump
	3) Heater core

=========================================================================
Mustangs FAQ Index
=========================================================================
Subject                              FAQ Section(s)
-------                              --------------
2.3L engine................................1
2.8L engine................................1
302 engine.................................1
4.2L engine................................1
5.0L engine................................1
7.5" rear..................................1
8.8" rear..................................1
air filter.................................1
air intake silencer........................1
AIR pump...................................1
amplifier..................................3
antenna....................................3
anti-lock brakes (aftermarket).............1
AOD........................................1
axle-ratio codes...........................2
body type codes............................2
CFI........................................1
Cobra......................................1
computer chips.............................1
cooling system.............................4
dashboard..................................3
door tag...................................2
EEC-IV.....................................1
EFI........................................1
EGR........................................1
engine type codes..........................2
Ford Motor Company.........................1
Ford Motorsport............................1
Fox........................................1
fuel pressure..............................1
glossary...................................1
GT-40......................................1
headers....................................1
heater core................................4
Mach 460 (see "stereo")
MAF........................................1
manuals....................................1
magazines..................................1
modular V8.................................1
mufflers...................................1
multiport fuel injection...................1
noise (electrical).........................3
Panhard rod................................1
pulleys....................................1,3
radio (see "stereo")
SFC (see "subframe connectors")
speed-density..............................1
smog pump (see "AIR pump)
spark plugs................................3
speakers...................................3
SROD.......................................1,2
stereo.....................................3
subframe connectors........................1
suspension (rear)..........................1
SVO........................................1
SVT........................................1
T-5........................................1,2
thermostat.................................1
timing.....................................1
torque arm.................................1
TPS........................................1
TracLink...................................1
Traction-Lok...............................1
transmission...............................1
transmission codes.........................2
underdrive pulleys (see "pulleys)
water pump.................................4
WOT........................................1

FAQ Part 1

MUSTANGS MAILING LIST FAQ - PART 1, Version 1.3
Last updated 1/5/95

NOTE:  The information in this document is correct to the best of the
author's knowledge.  However,  due to a change in employers the author will
not be able to update/correct this document in the future.  The author
accepts no responsibility for any damage, injury, or other "loss" you
encounter while working on your car.

[This document was put together by Andre Molyneux.  The following
individuals were of help putting it together or submitted information that
was pasted right in.  In alphabetical order: Peter Boggini, Ken Corpus
Chuck Fry, Gary Gitzen, and Dan Malek.]

Basic information and answers to the questions most often asked by
newcomers to the list.

The FAQ is available via anonymous ftp from the site:

	ftp.chucko.com

The FAQ resides in the directory "/fordnatics/mustangs-faq".  In addition,
an index is available that gives an idea of what subjects are covered by
each section of the FAQ.

This is the first installment of the FAQ (frequently asked questions) for
the Mustangs mailing list.  The FAQ is going to be broken up into multiple
sections as there are far too many subjects to be covered in detail in a
single document.  Future sections will cover such subjects as:

	- Basic Maintenance
	- Troubleshooting common problems
	- Suspension modifications
	- Brake system modifications
	- Engine modifications
	- Sound systems
	- Alarms

This portion of the FAQ will concentrate on basic information that is most
commonly requested by newcomers to the Mustangs list.  As a result, it
lacks the focus that later sections have.  As with the Mustangs mailing list
itself, the FAQ contains information concerning Mustangs based on Ford's
"Fox" platform (1979-1994) only.  No attempt will be made to include
information on earlier years.

This document is broken up into the following sections:

	1) Quick glossary of terms
	2) What manuals and publications are good sources of information?
	3) Ford addresses and phone numbers
	4) What modifications should I make to my car?
	5) What modifications can be made to my car for little or no money?


========================================================================
1) Quick glossary of terms
========================================================================

There are lots of terms and acronyms that make "Mustangese" difficult for
the uninitiated.  The following list is by no means comprehensive, but will
hopefully be enough to get you going:

2.3L
 Ford's 2.3 liter OHC inline 4-cylinder motor.  Available for all years
 1979-1993.  Turbocharged versions of this motor were first introduced in
 1979 but were quickly withdrawn due to reliability problems.  The turbos
 came back in the early Eighties, with the turbocharged and intercooled
 version found in the SVO Mustang being the most powerful version used.
2.8L
 Ford's 2.8 liter displacement V6 engine.  Available 1979-1986?
302
 For late-model Mustang purposes, the same thing as the 5.0L (302 cubic-
 inches approximately equaling 5.0 liters).
4.2L
 Also known as the 255, a de-stroked, de-bored version of the 302 that
 has no performance potential whatsoever.  However, a 302 will drop right
 in its place.  Yank the 4.2L and send it to the recycler to be made into
 something far more worthwhile, like razor blades.  Used in the 1981-82
 model years.
5.0L
 Ford's 5.0 liter displacement V8 engine.  The most popular motor for
 late-model Mustangs.  Available for 1979-1980 and 1983-1994.
7.5
 Refers to the 7.5" rear-end used in earlier 5.0L Mustangs and all 4 and 6
 cylinder Mustangs (not sure if this applies to the 1994 and later cars).
8.8
 Refers to the 8.8" rear-end used in later 5.0L Mustangs.  This unit is
 stronger than the 7.5" rear.
AOD
 Automatic OverDrive trasmission.
CFI
 "Central Fuel Injection", refers to a fuel metering system in which fuel
 is injected into the incoming air at a single point, after which the
 airflow is split up for individual cylinders (in contrast to multiport
 fuel injection).  Visually the system bears some resemblance to a
 carburetor, but the fuel metering is under electronic control.  CFI was
 used on '84 and '85 Mustangs with automatic transmissions mated to the
 2.8L V6 or 5.0L H.O., and is an EEC-IV controlled system.
Cobra
 In the late model Mustang world, refers to the highest-performance version
 of the Mustang available from the factory in 1993-95.  Cobra Mustangs have
 engine, braking, and suspension differences from other Mustangs.  "Cobra"
 is also used to refer to the version of the intake manifold used on the
 1993 Mustang Cobra, also known as the GT-41.  Originally referred to
 Carroll Shelby's Ford-powered race cars of the 1960's.
EEC-IV
 Ford's "Electronic Engine Control" computer, version number four.  Used on
 all 5.0 EFI equipped Mustangs from 1986 to 1994.  Some earlier CFI cars
 may have used the previous version (EEC-III).  Most Ford vehicles are now
 switching over to the EEC-V.
EFI
 "Electronic Fuel Injection", typically used to refer to multiport fuel
 injected cars.
EGR
 "Exhaust Gas Recirculation"  Refers to a valve used to pull exhaust gasses
 back into the intake manifold to reduce emissions.
Fox
 Ford's "Fox" chassis, which has been used for multiple cars including the
 1979-1994 Mustangs (other "Fox"-derived cars were the Fairmont, most of
 the 1980's Thunderbirds, and the Lincoln Mark VII).  A large number of
 components can be swapped between the various "Fox" cars, leading to
 interesting modifications on a budget.
GT-40
 In the late model Mustang world, refers to a version of the 5.0L V8 with
 higher-performance components than other 5.0's.  Originally referred to
 Ford's Production GT racing cars from the late 1960's.
MAF
 "Mass Air Flow"  Refers to a system in which the actual airflow into the
 engine is measured, as opposed to a speed-density system.  This term is
 often used both to describe the entire system or the MAF sensor which
 actually does the measuring.  All 1989+ 5.0 Mustangs, as well as 1988
 Mustangs destined for California, use a MAF system.
Modular V8
 New family of overhead-cam Ford V8 engines.  The Mustang has long been
 rumoured to be a recipient of this engine, as the 5.0L engine will not be
 able to meet stricter emissions requirements in the future.  This engine
 is currently available at a 4.6 liter displacement in single-overhead cam
 (approx. 210 hp) and double-overhead cam (approx. 280 hp), as compared to
 the 5.0L's 205 hp.  However, the modular motor produces less torque than
 the 5.0L and the powerband is shifted further up the RPM range.  The
 modular V8 is a very complex motor that will require more sophisticated
 hot-rodding techniques.  It's also quite expensive.  These factors will
 probably mean that the modular V8 will not become the panacea for Mustang
 performance.  Expect one of the versions of the modular V8 to appear in
 the Mustang in the 1996 model year (or possibly late in 1995).
Multiport Fuel Injection
 A fuel metering system in which each cylinder has a separate injector.
Panhard Rod
 A device used to control lateral movement of the axle.  A Panhard rod is
 connected to the chassis on one side of the car and to the axle at the
 other end.  Both ends require pivots to allow movement of the axle.  A
 Panhard is used in conjunction with a torque arm or other radical rear
 suspension modification, and is not considered to be an effective
 modification if added to an otherwise stock rear suspension.  Panhard
 rods have been in use on many different vehicles for many years.
SN95
 Ford designation for the fourth generation Mustang platform, introduced in
 the 1994 model year.  While it visually bears no resemblance to the
 previous generation Mustang, it is still based on a version of Ford's Fox
 platform, and shares most of its drivetrain and suspension design with
 the 1979-93 cars.
Speed-Density
 System in which the amount of air entering the engine is estimated based
 on several other inputs (such as manifold pressure).  The estimate is
 based on assumptions about the engine in use, so engine mods are more
 likely to confuse a speed-density system than a MAF system.  1986-1988
 5.0L Mustangs used speed-density systems (except 1988 cars destined for
 California, which used MAF).
SROD
 Ford's 4speed (three speed overdrive) transmission used in the 1979 and
 1982 to early 1983 5.0 mustangs.  SROD stands for Single Rail Over Drive.
Subframe Connectors
 Devices used to connect the front and rear subframes of a Mustang
 together.  The Mustang relies on the floor pan to connect the front and
 rear subframes, which results in a lot of flexing, making it difficult for
 the suspension to work correctly.  Subframe connectors install underneath
 the car (although there is one vendor with internal stiffeners that do
 much the same thing) and connect the front and rear frame rails directly.
 Subframe connectors should be welded in, as bolted on ones will eventually
 enlarge the bolt holes and become loose.  Many different vendors provide
 subframe connectors, with the favorite among list members being from
 Global West.
SVO
 Refers either to Ford's Special Vehicle Operations group or to the SVO
 Mustang, a 1984-1986 version of the Mustang that was the brainchild of
 this group.  In contrast to the V8 Mustangs, the SVO used a turbocharged
 and intercooled 2.3 liter 4-cylinder engine.  Aside from the 1993 Mustang
 Cobra, it was the only 1979-1993 Mustang to come from the factory with
 4-wheel disc brakes.
SVT
 Ford's "Special Vehicle Team".  Responsible for the Mustang Cobra and
 "Lightning" pickup truck.
T-5
 Borg-Warner T5 5-speed manual transmission.  Used on Mustangs from 1983?-
 1994.
Torque Arm
 A rear-suspension modification that yields a significant improvement in
 handling.  Installation of a torque-arm requires the removal of the rear
 upper control arms and the installation of a Panhard rod to control
 lateral movement of the axle.  This set-up significantly reduces bind in
 the rear suspension, allowing much more power to be applied when exiting a
 corner than the stock setup.  Installation of a torque arm and Panhard is
 a major (and expensive) undertaking.
TPS
 Throttle Position Sensor.  A potentiometer used to inform the EEC-IV how
 far the throttle is open.
TracLink
 A rear suspension upgrade that supplements the existing rear control arms,
 but doesn't replace any of them.  It improves handling by eliminating the
 axle's tendancy to rotate in the opposite direction of the wheels when
 torque is applied.  This prevents some of the tendency for bind in the rear
 suspension, but doesn't do as well as other more radical modifications.  
 Some racers have found that the TracLink will break under hard use.
 Global West makes the TracLink, but other manufacturers may have similar
 designs.
Traction-Lok
 Refers to the limited-slip type differential used in performance Mustangs.
 The purpose of the differential is to allow the rear wheels to turn at
 different speeds when going around a corner.  A Traction-Lok diff will
 limit the allowable difference in speeds between the two wheels, while a
 normal (or "open") differential has no such limits (if one tire has
 completely lost traction, it will spin merrily while the tire on the other
 side sits still).  The Traction-Lok is often referred to as the "Traction-
 Slop" as the factory spec allows it to lose much of its effectiveness
 through wear and yet still be "in spec".
WOT
 Short for "Wide open Throttle."  What happens when you floor the long
 pedal on the right.


========================================================================
2) What manuals and publications are good sources of information?
========================================================================

The FAQ documents are in no way intended to serve as a replacement for
repair manuals.  Manuals give step-by-step instructions that are a "must
have" for anyone who works on their own car.  On the Mustangs mailing list,
requests for information that is present in any of the major manuals will
usually get a response of RTFM ("read the *$%@ing manual" for those not
familiar with the term).  The following will give you an idea of what the
FM's are.  Anyone who can afford to insure a 5.0L Mustang has got to be
able to afford some (or all) of the relevant manuals.

- Factory Repair Manuals

The Ford factory manuals are published by:

	Helm Incorporated
	P.O. Box 07150
	Detroit, MI  48207
	(800) 782-4356

Helm accepts Visa and Mastercard orders.  The factory manuals are broken
down into various sets, such as basic servicing manual, emissions, wiring
diagrams, etc.  Most of the manuals are specific for one particular model
and year, but others (like emissions) span all vehicles for a particular
year.  Call Helm to determine exactly which manuals apply to your year of
car.

Note:  Be prepared for sticker-shock when you call.  The full set of
factory manuals will probably run in the vicinity of $200 (however, the
most used manual - the servicing manual - is typically under $60).  Still,
the factory manuals are almost a necessity if you do much wrenching on your
own car.  They are typically much more complete than any of the aftermarket
manuals, although they do have their own share of mistakes and omissions.

- Third-party repair manuals

Haynes, Chiltons, Clymers, and others make a wide variety of repair manuals
for all types of motor vehicles.  Haynes gets the nod as the best of this
crop.  Manuals typically span a wide variety of years, and may include
wiring diagrams.  However, omissions and mistakes due to the large number
of years covered make even the best of them problematic.  If you absolutely,
positively can't afford the factory repair manual, you _have_ to get one of
these.  Attacking almost any problem without the factory manual or a good
aftermarket substitute is an exercise in futility.

- Other references

 "How to Understand, Service, and Modify Ford Fuel Injection and Electronic
Engine Control" by Charles O. Probst, published by Robert Bentley of
Cambridge, MA, ISBN 0-8376-0301-3.  List price is $29.95.  Available direct
from the publisher at (800) 423-4595, through Ford Motorsport dealers and
some enlightened Mustang shops (including list member Ken Corpus, who sells
them at a discount to list members - contact Ken_Corpus.Wbst139@xerox.com),
or as a last resort, from Classic Motorbooks, (800) 826-6600, order # 119509.
This manual takes a lot of the mystery out of Ford's engine control computer.
A "must have" for anyone wanting to hot-rod a Ford EFI engine, or who just
wants to know how the hell it works.

Ford Motorsport SVO Performance Equipment Catalog:
This catalog consists of special, high-performance or competition parts or
accessories for various Ford vehicles, including the 5.0L Mustang.  There
are over 850 parts listed in the 1994 catalog, 40% of which are street legal.
The catalog also contains parts specifications, parts interchangeability and
compatibility information, hints about installation, and more.  SVO also
provides a technical assistance "hot line" that provides reliable, up-to-date
information about the equipment they sell.

- Magazines

I hesitate to recommend any of the Ford or Mustang rags.  Every now and
then you'll find a well-researched and relatively unbiased article, but
they're rare.  Remember that the magazines live by selling advertising
space, and debunking a manufacturer's claims could lead to a major loss of
revenue.  Take the articles (and especially the ads) with a large grain
of salt, say about the size of a salt-lick.  If you could believe what you
see on those glossy pages, a 300hp EFI street motor could be had for $250
and a couple of easy hours under the hood.  It just ain't that easy (or
cheap).


========================================================================
3) Ford addresses and phone numbers
========================================================================

- Important FoMoCo phone numbers

Ford Motor Company
Customer Assistance Center
P.O. Box 43360
Detroit, MI  48243
1-800-392-FORD
*Hearing Impaired Customers with TDD access call 1-800-232-5952

Tech. Service Bulletin hotline (is this still active?)
(800) 241-FORD

Ford Motorsport Performance Equipment
44020 N. Groesbeck Highway
Mt. Clemens, MI  48083-1115
Technical Assistance Hotline (313) 337-1356

Ford Motorcraft:  1-800-521-5181

Ford Audio & Cellular Systems:  1-800-FORD-333

Ford Online:  >>>   70007.1356@Compuserve.com   <<<
This is a fairly new service, which puts the Ford Customer Assistance
Center online with your computer thru the internet with CompuServe.  You
can send them just about any request for information, new car brocheres or
even complaints, and someone will typically respond to you within a day or
so .  Send them a note to the address listed above.


========================================================================
4) What modifications should I make to my Mustang?
========================================================================

This question comes up fairly often, but it's impossible to answer without
some idea of how you plan to use the car.  Are you looking to improve
straight-line acceleration?  Make it corner better?  Are you going to
drive the car only on the street or will you take it to the track?  Are you
going to drag race it, road race it, or just go cruise on Saturday nights?
Are you the only person driving it, or will your SO disown you if the car
no longer rides and drives like the average street car?

Almost any change you can make to the car involves tradeoffs.  Lowering the
car can improve handling, but you need to select the right springs and
shocks to keep from bottoming on the bump stops all the time, and you'll
tend to scrape the ground a bit.  Changes to improve weight-transfer and
grip for drag-strip launches are detrimental to the car's ability to
corner.  Adding a blower requires careful attention to fuel pressure, and
can cause your head gaskets (and other parts) to suddenly decide to get up
and move.  Slapping in a radical camshaft may improve top-end horsepower at
the expense of low-end torque, requiring you to rev the engine to keep from
stalling when pulling away from a stoplight.

Before you get visions of expensive toys in your head, sit down and decide
just what it is you want out of your Mustang.  Decide just how far you're
willing to change it from it's stock condition.  Have a goal in mind, even
if your goal's just to bolt on some expensive items to impress your
friends.  Once you've got that goal defined, then you can start finding out
how to reach that point.  The Mustangs list is a great source of info, but
you need to know what you're looking for.  Making a request for specific
information will get you far better responses than vague ramblings.


========================================================================
5) What modifications can be made to my Mustang for little or no money?
========================================================================

"Hot tips" of ways to improve performance for little or no money crop up
continuously.  Unfortunately, most of these "tips" are based on erroneous
assumptions, usually with regards to the EEC-IV.  This section will focus
on the most commonly suggested free/cheap mods, giving an idea of what they
hope to accomplish and whether the collective wisdom of those on the
mailing list lends them support or feels they do nothing (or actually hurt
performance).  Most of these mods are with regards to 5.0L Mustangs only,
and most concern EFI-equipped engines.

"Cheap" is arbitrarily defined here as $200 or less.  Most of the following
items cost significantly less (or are free), but a few approach the $200
mark.  In no particular order:


- Advance the base timing

The factory timing spec (10 degrees before top dead center) allows the
engine to run on "regular unleaded" 87 octane fuel.  If you're running a
higher octane fuel (premium unleaded is typically 92 octane), advancing the
timing will probably result in a few more horsepower.  The maximum base
advance typically possible on the 5.0L engines before ignition knock sets
in is 12 or 13 degrees BTDC.

VERDICT - Makes sense, but don't expect huge gains.


- Change (or remove) the factory thermostat

This is based on the fact that cooler air is denser, so the less you heat
the air coming into the engine, the more air/fuel mixture you can pack into
each cylinder.  An old shade-tree mechanic fix, but it's got several strikes
against it.  First, you never want to remove the thermostat completely.
The cooling system has been designed with the thermostat restriction in
mind, and removing it will actually _hurt_ cooling.  Second, cylinder wall
wear increases as operating temperatures are lowered.  The stock Mustang
thermostat is set for 196 degrees Fahrenheit.  Dropping to 180 will increase
wear somewhat, and dropping to 160 or 140 will increase wear dramatically.

On EFI cars, cooler thermostats are rumoured to increase performance
because the engine will run richer at temperatures below 180 degrees
Fahrenheit.  True, the EEC-IV will richen the mixture, but staying in "warm
up" mode entails more than just a richer mixture.  The EEC-IV will be more
conservative with the timing curves, and will never get into "closed loop"
operation (where it uses the oxygen sensors to fine-tune the mixture).  The
result will likely be poorer drivability and _decreased_ performance.
Also, catalytic converters can be damaged over time by an engine that's
continually running rich.

VERDICT - Don't remove the thermostat entirely, and don't use a thermostat
below 180 degrees Fahrenheit on an EFI car.


- Underdrive Pulleys

The idea here is to reduce the parasitic loads on the engine, freeing up
more power to go to the rear wheels.  Underdriving the accessories will
reduce the loads, but not as much as the manufacturer's ads would have you
believe.  The accessory loading isn't linear, so reducing an accessory's
RPMs by a third won't reduce the needed power by a third.  In addition, if
the alternator is underdriven, it may not provide enough power to keep all
the electrical loads happy at lower RPMs (especially if you have a mega-watt
stereo), and underdriving the power steering pump may result in increased
steering effort when idling through the parking lot.

There is another reason to underdrive accessories.  The accessories were
designed to operate at a particular RPM for most of their lives, and can
fail or cause problems if run at higher RPMs for long periods of time.
This becomes a problem for cars that run on the track.  Installing
underdrive pulleys in these situations can put the accessories back at
their normal operating speeds and increase their useful life.

VERDICT - You may pick up a couple of horsepower, but be careful or you may
end up with a dead battery.  If you run on the track, your power steering
pump will thank you.


- Mufflers

Eliminating bottlenecks anywhere in the intake or exhaust systems is almost
always a help.  However, the mufflers are part of a larger system and can
only do so much by themselves.  The factory headers, catalysts, and pipes
put a limit on how much can be gained by replacing the mufflers.
Aftermarket mufflers result in very modest gains on an otherwise stock
system, but become a necessity as flow in the rest of the system is
improved.

VERDICT - Good as part of an overall exhaust system improvement, otherwise
buy them for the sound, not the performance gain.


- Disconnecting the EGR valve

Pumping partially-burned exhaust gasses back into the intake has gotta be a
brain-dead idea, no?  No.  The EGR valve only operates at part-throttle
settings, and uses the exhaust gasses to lower combustion temperatures and
reduce the formation of nitrogen oxides, a component of smog.  At idle and
WOT, the EGR valve is closed, so performance really isn't compromised.

On the last few years of carb-equipped 5.0 engines, the EGR can appear to
cause a "stumbling" problem that goes away if the valve is disabled.  The
real problem appears to be getting the correct mixture and timing.  If these
are set correctly, the "stumbling" problem is significantly reduced (or
eliminated) without disabling the EGR.

VERDICT - Don't do it.


- Remove EGR coolant lines (EFI engines only)

The coolant circulated to the EGR spacer is there to take heat _away_ from
the spacer, not heat it up.  The exhaust tube to the EGR is carrying gasses
significantly hotter than the coolant, so eliminating the coolant flow will
only make things hotter.

VERDICT - Don't do it.


- Air Filter

K&N sells a reusable air filter element that just requires periodic
cleaning and re-oiling.  Whether or not the K&N is better than a clean
paper filter is debatable.  However, if you clean it more often than you
would replace a paper filter, on average it will present less of an
obstruction.  The instructions give some insane cleaning interval (like
50,000 miles or so), but I clean mine at least every other oil change.

VERDICT - Use it, but clean it regularly


- Air Intake Silencer (EFI engines only)

The air intake silencer is located next to the air filter housing, on the
opposite side of the sheetmetal (inside the fender).  It's a big plastic
doohickey with more than a passing resemblance to a Jarvik artificial heart.
It's sole purpose in life is to quiet down the air as it's sucked into the
engine.  The silencer presents a bit of an obstruction to air flow, so
removing it will put you one step closer to a better intake path.

VERDICT - Yank that puppy.  Why should you only hear the exhaust?


- Bypass the AIR pump with a shorter belt

The AIR (air induced reaction) pump, commonly known as the smog pump, pumps
fresh air into the exhaust system to help the catalysts burn any remaining
unburned hydrocarbons.  Installing a shorter belt to bypass the AIR pump
doesn't make much sense because at WOT the pump's output is just dumped
back into the atmosphere rather than into the exhaust system.  When the
output is dumped the pump requires very little power to run, so the
performance gain is essentially non-existent.  Also, don't expect to bypass
the pump and then put the original belt back on right before smog-check
time.  AIR pumps tend to seize after a while when they're not being driven,
so all you'll do is end up having to shell out money for a new one anyway.

VERDICT - Don't do it.


- Crank up the fuel pressure (EFI engines only)

Increasing the fuel pressure on an otherwise stock engine (by by going to
an aftermarket regulator) is a bad idea.  Within limits, the EEC-IV will
compensate for the excess fuel by reducing the injector duty cycle.  Beyond
this, it will give up and resort to "limp home" mode, in which your engine
will run like dog meat.  Modified engines sometimes require additional fuel
pressure to keep up with the higher airflow, but on a stock engine you're
wasting your time.

VERDICT - Don't do it.


- Disconnect the vacuum line to the fuel pressure regulator (EFI only)

This modification has exactly the opposite of the desired effect: It
increases the effective idle fuel pressure without raising the fuel
pressure at WOT.  At best, the EEC-IV will eventually compensate for
this blunder under closed-loop operation, but will never notice it at
WOT.  At worst, the EEC will adjust the mixture at *all* vacuum levels
to correspond with the observed fuel delivery during part-throttle,
high-vacuum operation, resulting in a leanout at WOT.

VERDICT - Don't do it.


- Performance chips (EFI engines only)
  (~$200 for Hypertech or Superchips)

Unlike some other manufacturers, Ford hasn't been too open with information
about their engine control computer, and designed it such that ROM-swapping
isn't feasible.  As a result, and aftermarket engine "chips" must either
intercept the signals to/from the computer or plug into the EEC-IV's
diagnostic port.

Getting more power out of an engine requires moving more air through it or
making more efficient use out of the air and fuel you've got.  There are no
emissions requirements that must be met at WOT, so the computer has no
reason to hold back when you push the pedal to the floor.  Small gains can
be realized by bumping up the timing a few degrees, but you can do very
much the same thing manually by advancing the base timing (see the first
item on this list).  Most of the reputable sources dismiss aftermarket chips
for stock engines (radically modified cars may require mods, however).

A couple of list members received free evaluation chips from a company
called "Superchips".  These went on a '92 LX and '94 GT, both of them
stock 5-speeds.  On the '92, back-to-back runs were done on the dyno, one
with the chip installed and one without.  A small power gain was seen across
the powerband, but several factors (the engine was set at the stock 10
degrees BTDC without the chip, and the engine and dyno were both hotter
during the chipless run) lead to the conclusion that the gain from the chip
was very small indeed compared to what could be gotten simply by advancing
the timing by hand.  Back-to-back runs weren't possible for the '94, but
comparing the run to a previous dyno run by the same car months earlier
(and correcting by the differences found on a car that had been run on both
days) indicated a *loss* of power.  On both cars the engine analyzer
indicated that the chip had leaned out the mixture at WOT, apparently too
much on the '94.

VERDICT - Of very questionable benefit.  Why not spend your money on known
performance improvers instead?


- Aftermarket "Anti-Lock" brakes
  (Not sure if this is under $200, but it crops up about every 6 months)

Anti-lock braking systems have become increasingly popular, but they
weren't available on the Mustang until 1994.  There is at least one
manufacturer of a mechanical system (as opposed to the electronically-
controlled system used by auto manufacturers) that can be used on the
Mustang.  The manufacturer's literature hints that their product is
superior to the electronic systems because the electronic systems only
kick in when a wheel has locked, whereas the mechanical system prevents
lock-up in the first place.  This is pretty misleading.

Electronic ABS has sensors that detect the instant a wheel has stopped
rotating.  When this happens, brake pressure to that wheel is momentarily
reduced until the wheel starts turning again.  The system response is
extremely fast, and the amount of time that the wheel has stopped turning
is extremely small.  This sophisticated "closed-loop" system allows the
brakes to work at right about their maximum capacity without locking a
wheel for more than a small fraction of a second.

On the other hand, the mechanical system attempts to prevent sudden
transients in brake system pressure.  This means that when you apply sudden
pressure to the brake pedal, the system will damp down rate of pressure
buildup in the system.  This is all well and good for "Joe and Mary
Sixpack" who tend to lock up the brakes when the light turns red 200 yards
down the road.  It's bad for someone who knows how to use their brakes
correctly, as it will slow down the system's response to your input.  Your
right foot says "I want maximum braking now!" which the system interprets
to "Ok, let's increase the brake pressure, but not too quickly, we don't
want to rush this."

If you practice your braking technique, you'll find the point at which
you can brake the hardest without locking up a wheel.  You'll discover that
you can stop quicker by yourself than with the mechanical ABS.  Experienced
track drivers are divided on the usefulness of electronic ABS, but I doubt
you'll find one in favor of the mechanical version.

VERDICT - Don't do it.


- Install aftermarket headers

The factory headers on '85(?)-up Mustangs are lighter than the cast iron
manifolds they replace.  However, that is about their only benefit.  The
tubes are crimped and contorted, partly to make room for factory
installation tools, partly because it's cheaper to build them that way.

Several brands of aftermarket replacement headers are available for
$200/pair or less, and all are 50-state smog-legal if installed on the
model year(s) for which they are intended.  All are an improvement over
the stock headers in terms of airflow, yielding on the order of 5 to 8
HP and a small improvement in fuel economy.

However, there are a number of choices to make: tubing size (1-1/2" vs
1-5/8), equal vs unequal length, plated vs ceramic-coated vs stainless.
Various magazine tests have shown minimal performance differences on
stock Mustangs, so in many cases the choice comes down to cost and
availability.

Before you install them, inspect the headers carefully for weld quality.
Often the internal seams will be sloppy.  A few minutes with a die
grinder will remove these imperfections, maximizing the benefits gained
from the headers.  Doing this to the factory headers would help as well,
but if you're going to the trouble you might as well buy the better
afteremarket units.

VERDICT - Makes sense, but don't expect huge gains, and do clean them up
first.

END OF MUSTANGS MAILING LIST FAQ - PART 1