1993 Coupe Hard Starting

fastgtracer

New Member
Jun 13, 2009
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Florida
I have looked through the posts regarding hard starts & seem to be coming up empty. Recently the idle was bumped up so that the car would not stall with the ac running (prior to that the car would always start on the first crank), and the hard start seemed to follow. Starter does not appear to be dragging it cranks hard all the time just wont turn over. Have checked the resistance of the ECT sensor ,replaced the MSD coil with factory coil, with pedal to the floor does not appear to help . Car has this issue whether cold or hot. BBK 190 fuel pump, FMS 30# injectors, bbk fuel pressure regulator, running 32lbs pressure with vacuum line connected . Car is using the factory computer (soon to be converted to the MegaSquirt 2 system) . Any help or suggestions would be appreciated....
 
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So you are saying it cranks hard but won't turn over? That doesn't make sense? Does the engine turn when you turn the key?

One red flag I see is that you said you have to up the idle screw to keep it from stalling when the A/C comes on. This tells me that the IAC valve that controls idle is slow or has gone out. This can make it hard for the engine to start and keep idling.

First, verify that you have a good battery. Then verify if you have good connections. If all this is good, it may be the starter is weak. My buddy just replaced his starter because it could barely turn over the engine.
 
It cranks strong I should have said ( meaning it is not struggling to crank , like as in a weak battery) mini racing starter, Optima Red Top. Everything has less than 1000 miles on it other than the stock sensors . The car definitely needs a tune either with a diablo chip or an aftermarket computer. So the only issue the car had was when the ac was on idle dropped to around 500 as I am assuming the factory computer cannot properly process the needs of the bigger motor, need for more air & fuel etc.... So I adjusted the idle so when the ac is on the car idles at about 800 & around 900 without the ac on. Could this be causing the hard start issues? Do I need to back down the fuel pressure? Before adjusting the idle the car always fired up on the first turn of the key (hot or cold). Eventually the car will start, have noticed when I let go of the key during cranking I will occasionally hear what sounds like a puff of air . No vacuum leaks to be found. I am guessing it is an air/fuel/idle issue. From reading other posts I could be chasing around unless I get the codes pulled from the factory computer, is this the 1st place to start? Thanks for the replies
 
You say you have a bigger motor? You prob need to post up everything about your engine specs, size, cam, headers, etc.

Most likely if you have some major mods the stock comp will not operate the engine correctly. I went through the same thing you seem to have going on and I know first hand that a proper tune will solve ALOT of problems.
 
This is as much as I know about the motor. This is what I have found going through all the Summit receipts. But as I noted before this hard start problem was not there the first 500 miles I drove the car



FMS Aluminum Heads
FMS Valve Covers
Speed Pro Coated Hypereutectic Pistons
FMS X303 Camshaft
FMS R303 Hyd Roller
BBK SSI Manifold
BBK 70MM Throttle Body
BBK 30# Injectors
BBK Fuel Pressure Regulator/Guage
BBK Shorty Headers
Summit Mass Air
MSD Blaster Coil/Distributor/6AL
Trick Flow Harmonic Damper
Stage 2 Racing Clutch
BBK Clutch Quadrant
Griffin Aluminum Radiator
Optima Red Top Relocated to trunk
Factory Air Conditioning
Mini Torque Starter
Under Drive Pulleys
 
When it won't start, do the checklist...

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

A word about this checklist before you start: it is arranged in a specific order to put the most likely failure items first. That will save you time, energy and money. Start at the top of the list and work your way down. Jumping around will possibly cause you to miss just what you need to see to find and fix the problem. Don’t skip any steps because the next step depends on the last step working correctly.


Revised 16-Jan-2011 to clarify testing the EEC relay in paragraph 1E .

All text applies to all models unless stated otherwise.

Note: 94-95 specific changes are in red

1.) Remove push on connector (small red/blue wire) from starter solenoid and turn ignition switch to the Run position. Place car in neutral or Park and set the parking brake. Remove the coil wire from distributor & and hold it 3/8” away from the engine block. Jumper the screw to the big bolt on the starter solenoid that has the battery wire connected to it. You should get a nice fat blue spark.
Most of the items are electrical in nature, so a test light, or even better, a voltmeter, is helpful to be sure they have power to them.

No spark, possible failed items in order of their probability:
A.) MSD or Crane ignition box if so equipped
B.) PIP sensor in distributor. The PIP sensor supplies the timing pulse to trigger the TFI and injectors. A failing PIP sensor will sometimes let the engine start if the SPOUT is removed. See paragraph 5A – Using a noid light will tell if the PIP is working by flashing when the engine is cranking.
C.) TFI module: use a test light to check the TFI module. Place one lead of the test light on the red/green wire on the ignition coil connector and the other lead on the dark green/yellow wire on the ignition coil connector. If the TFI is working properly, the test light will flash when the engine is cranked using the ignition switch.
D.) Coil
E.) No EEC or computer power - EEC or computer relay failure
86-93 models only: EEC relay next to computer - look for 12 volts at the fuel injector red wires.
94-95 models only: EEC or PCM power relay in the constant control relay module. Look for 12 volts at the fuel injector red wires.
Both 86-93 and 94-95 models: No 12 volts with the ignition switch in the run position on the fuel injector red wires. The relay has failed or there is no power coming from the ignition switch. Make sure that there is 12 volts on the red/green wire on the coil before replacing the relay.
F.) No EEC or computer power - fuse or fuse link failure
86-93 models only: Fuse links in wiring harness - look for 12 volts at the fuel injector red wires. All the fuse links live in a bundle up near the starter solenoid. Look for a 20 gauge blue fuse link connected to 2 black/orange 14 gauge wires.
94-95 models only: 20 amp EEC fuse in the engine compartment fuse box. Look for 12 volts at the fuel injector red wires.
G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire. No 12 volts, blown fuse link or faulty ignition switch. Remove the plastic from around the ignition switch and look for 12 volts on the red/green wire on the ignition switch with it in the Run position. No 12 volts and the ignition switch is faulty. If 12 volts is present in the Run position at the ignition switch but not at the coil, then the fuse or fuse link is blown.
Note: fuses or fuse links blow for a reason. Don’t replace either a fuse or fuse link with one with a larger rating than stock. Doing so invites an electrical fire.
Ignition fuse links may be replaced with an inline fuse holder and 5 amp fuse for troubleshooting purposes.
94-95 models only: Check inside fuse panel for fuse #18 blown – 20 amp fuse
H.) Missing or loose computer power ground. The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery.
In 86-90 model cars, it is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
In 91-95 model cars it is a black cylinder about 2 1/2" long by 1" diameter with a black/white wire.
You'll find it up next to the starter solenoid where the wire goes into the wiring harness
I.) Computer.
J.) Bad or missing secondary power ground. It is located between the back of the intake manifold and the driver's side firewall. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges.
K.) Engine fires briefly, but dies immediately when the key is released to the Run position. Crank the engine & when it fires off, pull the small push on connector (red wire) off the starter relay (Looks like it is stuck on a screw). Hold the switch in the crank position: if it continues to run there is a problem with either the ignition switch or TFI module. Check for 12 volts at the red/green wire on the coil with the switch in the Run position. Good 12 volts, then replace the TFI. No 12 volts, replace the ignition switch.

Wiring Diagrams:

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Engine Information Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 94-95 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/94-95_5.0_EEC_Wiring_Diagram.gif


AutoZone wiring diagrams: You can navigate to the diagrams yourself via Repair Info | AutoZone.com and select the car year, make, model and engine. That will enable you to bring up the wiring diagram for your particular car.

2.) Spark at coil wire, pull #1 plug wire off at the spark plug and check to see spark. No spark, possible failed items in order of their probability: [/b]
A.) Moisture inside distributor – remove cap, dry off & spray with WD40
B.) Distributor cap
C.) Rotor
D.) Spark Plug wires
E.) Coil weak or intermittent - you should see 3/8" fat blue spark with a good coil

3.) Spark at spark plug, but no start.
Next, get a can of starting fluid (ether) from your local auto parts store: costs a $1.30 or so. Then pull the air duct off at the throttle body elbow, open the throttle, and spray the ether in it. Reconnect the air duct and try to start the car. Do not try to start the car without reconnecting the air duct.

Two reasons:
1.) If it backfires, the chance for a serious fire is increased.
2.) On Mass Air cars, the computer needs to measure the MAF flow once the engine starts.
If it starts then, you have a fuel management issue. Continue the checklist with emphasis of fuel related items that follow. If it doesn’t, then it is a computer or timing issue: see Step 4.

Clue – listen for the fuel pump to prime when you first turn the ignition switch on. It should run for 5-20 seconds and shut off. To trick the fuel pump into running, find the EEC test connector and jump the connector in the Upper RH corner to ground. The EEC connector is near the wiper motor and LH hood hinge.
attachment.php


If the relay & inertia switch are OK, you will have power to the pump. Check fuel pressure – remove the cap from the Schrader valve behind the alternator and depress the core. Fuel should squirt out, catch it in a rag. Beware of fire hazard when you do this. In a pinch, you can use a tire pressure gauge to measure the fuel pressure. It may not be completely accurate, but you will have some clue as to how much pressure you have. If you have any doubts about having sufficient fuel flow/pressure, rent a fuel pressure test gauge from the auto parts store. That will tell you for sure if you have adequate fuel pressure.


4.) No fuel pressure, possible failed items in order of their probability:
A.) Tripped inertia switch – Coupe & hatch cars hide it under the plastic trim covering the driver's side taillight. Use the voltmeter or test light to make sure you have power to both sides of the switch
B.) Fuel pump power relay – located under the driver’s seat in most stangs built before 92. On 92 and later model cars it is located below the Mass Air Flow meter. Look for 12 volts at the Pink/Black wire on the fuel pump relay.
C.) Clogged fuel filter
D.) Failed fuel pump
E.) 86-90 models only: Blown fuse link in wiring harness. Look for 12 volts at the Orange/Lt Blue wire on the fuel pump relay.
91-93 models only Blown fuse link in wiring harness. Look for 12 volts at the Pink/Black wire on the fuel pump relay.
The fuse links for all model years 86-93 live in the wiring harness near the starter solenoid.
94-95 models only: 20 amp fuel pump fuse in the engine compartment fuse box. Look for 12 volts at the Dark green/yellow wire on the constant control relay module.
F.) Engine seem to load up on fuel and may have black smoke at the tailpipe. Fuel pressure regulator failed. Remove the vacuum line from the regulator and inspect for fuel escaping while the pump is running. If fuel is coming out the vacuum port, the regulator has failed. Check the regulator vacuum line for fuel too. Disconnect it from the engine and blow air though it. If you find gas, the regulator has failed.

5.) Fuel pressure OK, the injectors are not firing.
A.) The PIP sensor in the distributor tells the computer when to fire the injectors. A failing PIP sensor will sometimes let the engine start if the SPOUT is removed.
A noid light available from any auto parts store, is one way to test the injector circuit to see if the injectors are firing. The noid light plugs into the fuel injector harness in place of any easily accessible injector. Plug it in and try to start the engine: it will flash if the injector is firing.
B.) I like to use an old injector with compressed air applied to the injector where the fuel rail would normally connect. I hook the whole thing up, apply compressed air to the injector and stick it in a paper cup of soapy water. When the engine cranks with the ignition switch on, if the injector fires, it makes bubbles. Cheap if you have the stuff laying around, and works good too.
D.) Pull an injector wire connector off and look for 12 volts on the red wire when the ignition switch is on.
E.) No power, then look for problems with the 10 pin connecter (salt & pepper shakers at the rear of the upper manifold).
See the graphic for the 10 pin connector circuit layout.
harness02.gif

The injector power pin is the VPWR pin in the black 10 pin connector.

F.) No power and the 10 pin connections are good: look for broken wiring between the orange/black wire on the EEC relay and the red wire for the 10 pin connectors.
G.) TPS voltage exceeds 3.7 volts with the throttle closed. This will shut off the injectors, since the computer uses this strategy to clear a flooded engine. Use a DVM, a pair of safety pins, and probe the black/white and green wires to measure the TPS voltage.
On a 94-95 Mustang, probe the black/white and grey/white wires to measure the TPS voltage.
It should be .5-.1.0 volts with the key on, engine not running. Note that if the black/white wire (signal ground) has a bad connection, you will get some strange readings. Make a second measurement using the battery post as the ground to eliminate any ground problems. If the readings are different by more than 5%, you may have a high resistance condition in the black/white signal ground circuit.

6.) Spark & fuel pressure OK.
A.) Failed IAB or improperly set base idle (no airflow to start engine). Press the throttle ¼ way down and try to start the car. See the "Surging Idle Checklist for help with all your idle/stall problems.
B.) Failed computer (not very likely)
C.) Engine ignition or cam timing off: only likely if the engine has been worked on recently. If you removed the distributor, there is a good probability that you installed it 180 degrees out of time.
D.) Firing order off: HO & 351 use a different firing order from the non HO engines.
HO & 351W 1-3-7-2-6-5-4-8
Non HO 1-5-4-2-6-3-7-8
E.) No start when hot - Press the throttle to the floor & try starting it if you get this far. If it starts, replace the ECT.
F. ) Engine that has had the heads off or valves adjusted. Do a compression test to make sure the valves are not adjusted too tight. You should have a minimum of 90 PSI on a cold engine.
 
I see that you have an aftermarket fuel pump. Are you sure it's good?
My fox started getting really hard to start and someone told me to try
turning the key on and off 5 or 6 times before trying to start it and see if it made a difference. (to where you here the pump run and shut off)
I tried it and it started right up. The pump was going bad.
Might be worth a shot
 
OLDFOX thanks for the input. I did verify that the fuel pump is kicking on for about 5 seconds with every turn of the key ( I would hope its not going bad it is less than 6 months old) . Tested the car today, drove it about 30 miles & did not turn on the a/c . Car never got over 190 & when I got it home & let it sit for about 15 minutes it would crank good & strong but it would take 5 or 6 times of cranking it before it would start (could smell fuel for sure). I am going to start working on the checklist in the above post, it just seems strange that this all started after I bumped up the idle about 250-300 RPM . Thanks for all the input, will post my findings as I troubleshoot the issue.
 
Codes Pulled from EEC-IV

Partial problem fixed. When the spark was checked there was intermittent spark when firing. Disconnected MSD 6AL box & just running the MSD Coil, car has good spark & fires up like it used to ,need to check power/ground to MSD 6AL.

Finally pulled the codes with the Equus #3145 ODB1 Code Reader running the KOEO test. Codes are : 67,81,82,85 (Codes from the O code test), then received code 22 (code from the C continuous memory test).

A little info about the motor: FMS Aluminum Heads
FMS Valve Covers
Speed Pro Coated Hypereutectic Pistons
FMS X303 Camshaft
FMS R303 Hyd Roller
BBK SSI Manifold
BBK 70MM Throttle Body
BBK 30# Injectors
BBK Fuel Pressure Regulator/Guage
BBK Shorty Headers
Summit Mass Air Sensor 75MM Bullet (29052B-C)
MSD Blaster Coil/Distributor/6AL
Trick Flow Harmonic Damper
Stage 2 Racing Clutch
BBK Clutch Quadrant
Griffin Aluminum Radiator
Optima Red Top Relocated to trunk
Factory Air Conditioning
T5 5 speed transmission


Have the book that defines the codes but I do not understand all the sensors/codes (as code 67 has 5 different definitions not sure which would apply considering this is not the stock motor in the car)
 
Fuel pump relay? Sounds like it, because you are cranking it for a while strong, then comes on later. Well that's after the computer turns the pump on. When you turn the key, does it prime the pump for a second? If not, I am betting on a fuel pump relay.

I still think you have a slow IAC motor. (idle air control valve) as these are a common problem in fords.
 
Code 67 - clutch not depressed (5 speed) or car not in neutral or park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code may prevent you from running the Key On Engine On tests. You can generally ignore this code, since it has no effect on engine performance.

The computer wants to make sure the A/C is off due to the added load on the engine for the engine running tests. It also checks to see that the transmission is in Neutral and the clutch depressed (T5, T56, Tremec 3550 & TKO)). This prevents the diagnostics from being run when the car is driven. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.

The NSS code 67 can be bypassed for testing. You will need to temporarily ground computer pin 30 to the chassis. Computer pin 30 uses a Lt blue/yellow wire. Remove the passenger side kick panel and then remove the plastic cover from the computer wiring connector. Use a safety pin to probe the connector from the rear. Jumper the safety pin to the ground near the computer.
Be sure to remove the jumper BEFORE attempting to drive the car!!!


Code 81 – Secondary Air Injection Diverter Solenoid failure AM2. The solenoid valve located on the back side of the passenger side wheel well is not functional. Possible bad wiring, bad connections, missing or defective solenoid valve. Check the solenoid valve for +12 volts at the Red wire and look for the Lt Green/Black wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the LT Green/Black wire for the solenoid valve.

With the with the ignition on, look for 12 volts on the red wire on the solenoid connector. No 12 volts and you have wiring problems.

With the engine running, stick a safety pin in the LT Green/Black wire for the solenoid valve & ground it. That should turn the solenoid on and cause air to flow out the port that goes to the pipe connected to the cats. If it doesn't, the valve is bad. If it does cause the airflow to switch, the computer or wiring going to the computer is not signaling the solenoid valve to open.

Putting the computer into self test mode will cause the solenoid valve to toggle. If you listen carefully, you may hear it change states.

Code 82 – Secondary Air Injection Diverter Solenoid failure AM1. Possible bad wiring, bad connections, missing or defective solenoid valve. Check the solenoid valve for +12 volts at the Red wire and look for the Red/White wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the Red/White wire for the solenoid valve

With the engine running, stick a safety pin in the Red/White wire for the solenoid valve & ground it. That should turn the solenoid on and cause air to flow out the port that goes to the pipe connected to the heads. If it doesn't, the valve is bad. If it does cause the airflow to switch, the computer or wiring going to the computer is not signaling the solenoid valve to open.

Both 81 & 82 codes usually mean that some uneducated person removed the solenoid control valves for the Thermactor Air system in an attempt to make the car faster. It doesn't work that way: no working control valves can cause the cat converters to choke and clog.


Code 85 - CANP solenoid - The Carbon Canister solenoid is inoperative or missing. Check vacuum lines for leaks and cracks. Check electrical wiring for loose connections, damaged wiring and insulation. Check solenoid valve operation by grounding the gray/yellow wire to the solenoid and blowing through it.
The computer provides the ground for the solenoid. The red wire to the solenoid is always energized any time the ignition switch is in the run position.

Charcoal canister plumbing - one 3/8" tube from the bottom of the upper manifold to the rubber hose. Rubber hose connects to one side of the canister solenoid valve. Other side of the solenoid valve connects to one side of the canister. The other side of the canister connects to a rubber hose that connects to a line that goes all the way back to the gas tank. There is an electrical connector coming from the passenger side injector harness near #1 injector that plugs into the canister solenoid valve. It's purpose is to vent the gas tank. The solenoid valve opens at cruse to provide some extra fuel. The canister is normally mounted on the passenger side frame rail near the smog pump pulley.

attachment.php


It does not weigh but a pound or so and helps richen up the cruse mixture. It draws no HP & keeps the car from smelling like gasoline in a closed garage. So with all these good things and no bad ones, why not hook it up & use it?


The purge valve solenoid connector is a dangling wire that is near the ECT sensor and oil filler on the passenger side rocker cover. The actual solenoid valve is down next to the carbon canister. There is about 12"-16" of wire that runs parallel to the canister vent hose that comes off the bottom side of the upper intake manifold. That hose connects one port of the solenoid valve; the other port connects to the carbon canister.

Purge valve solenoid:
6



The carbon canister is normally mounted on the passenger side frame rail near the smog pump pulley.
Carbon Canister:
getimage.php




Fix the code 22 first. It is critical to the car's performance and economy
On a Mass Air car, the MAP sensor vents to open air and actually acts to sense the barometric pressure. It becomes a Barometric Air pressure sensor. It's purpose is to set a baseline for the computer to know the height above sea level. The fuel requirements decrease as altitude increases, since the atmospheric pressure decreases. As altitude increases, it leans out the fuel flow to compensate for less oxygen in the air.

Disconnecting the MAP or BARO sensor will set code 22.

Misconnecting the BARO sensor to vacuum on a Mass Air car will cause the computer to lean out the fuel mixture.

Code 22 or 126 MAP (vacuum) or BARO signal out of range. The MAP or BARO sensor is pretty much the same sensor for both Mass Air & Speed Density cars. The main difference is where it is connected. Mass Air cars vent it to the atmosphere, while Speed Density cars connect it to the intake manifold vacuum. Its purpose is to help set a baseline for the air/fuel mixture by sensing changes in barometric pressure. The MAP or BAP sensor puts out a 5 volt square wave that changes frequency with variations in atmospheric pressure. The base is 154 HZ at 29.92" of mercury - dry sunny day at sea level, about 68-72 degrees. You need an oscilloscope or frequency meter to measure it. There a very few DVM with a price tag under $40 that will measure frequency, but there are some out there.

The MAP/BARO sensor is mounted on the firewall behind the upper manifold on 86-93 Mustangs.

Baro or MAP test using frequency meter - run the test key on engine off. The noise from the ignition system will likely upset the frequency meter. I used a 10 x oscilloscope probe connected from the frequency meter to the MAP/BAP to reduce the jitter in the meter's readout.

If it is defective, your air/fuel ratio will be off and the car’s performance & emissions will suffer

Some basic checks you can make to be sure that the sensor is getting power & ground:
Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.
Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohm. Next check the resistance between the black/white wire and the negative battery cable. It should be less than 1.5 ohm.

The following power on check requires you to turn the ignition switch to the Run position.
Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or EGR sensors. Use the black/white wire for the ground for the DVM.
 
The fuel pump does kick on for about 4 seconds when the key is turned on, and the car is now firing on the first turn of the key after bypassing the MSD 6AL box. I wanted to see what codes were being generated so the KOEO test was ran, but are the codes true issues or mis-reads by a factory computer with an engine with mods.
jrichker the clutch was not depressed at the time of test. If I am not mistaken I believe the code 81 & 82 are being generated because these sylenoids have been removed by the prior owner ( will check to verify). My question is regarding the MAP sensor code, can the X cam not cause the vacuum level to drop, causing the EEC-IV to think that the car has a vacuum issue and cause it to run rich( generating a false code ) in cars that have a larger than factory camshaft. I wonder if a brand new MAP sensor would spit out a code also because of the bigger cam & the factory computer thinking there is a problem with the MAP sensor. Will check for the removal of the sylenoids from the codes 81, 85. I understand until the factory EEC is upgraded there is the potential for codes that may not be affecting the performance but rather codes being generated because the factory computer cannot compensate for the engine modifications.
 
The fuel pump does kick on for about 4 seconds when the key is turned on, and the car is now firing on the first turn of the key after bypassing the MSD 6AL box. I wanted to see what codes were being generated so the KOEO test was ran, but are the codes true issues or mis-reads by a factory computer with an engine with mods.
jrichker the clutch was not depressed at the time of test. If I am not mistaken I believe the code 81 & 82 are being generated because these sylenoids have been removed by the prior owner ( will check to verify). My question is regarding the MAP sensor code, can the X cam not cause the vacuum level to drop, causing the EEC-IV to think that the car has a vacuum issue and cause it to run rich( generating a false code ) in cars that have a larger than factory camshaft. I wonder if a brand new MAP sensor would spit out a code also because of the bigger cam & the factory computer thinking there is a problem with the MAP sensor. Will check for the removal of the sylenoids from the codes 81, 85. I understand until the factory EEC is upgraded there is the potential for codes that may not be affecting the performance but rather codes being generated because the factory computer cannot compensate for the engine modifications.

On Mass Air computer engines the MAP sensor is vented to open air and it becomes a Baro sensor. Connecting it to vacuum will cause problems. There is no vacuum sensor on Mass Air computer engines, so engine vacuum does not affect computer sensor operation.

The stock computer works very well with engine modifcations with no changes necessary unless the injector size is changes. At that point either an aftermarket MAF to match the injector size or custom dyno tune chip is needed to accomodate the larger inectors. The 30 pound injectors are a little large for a 302-306 engine, and may be part of your problem.

Diagram courtesy of Tmoss & Stang&2birds
88-91_5.0_EEC_Wiring_Diagram.gif


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif
 
Problem has been solved, sorry for the very late reply. Just learned how to navigate this site and find my original posts.Wanted to post what I found so others experiencing this problem can check. It was a broken hall effect sensor in my MSD distributor. Took the cap off the distributor and it was laying in the bottom of the distributor. MSD confirmed that this is common with the distributor I have (MSD 8456 Pro Billet) and they have redesigned the distributor. Thank you jrichker for the checklist!