Engine Stuck On The Side Of The Road

joepawlenty

Active User
Sep 13, 2017
22
0
1
Hello all,

I am new to this forum and new to the 5.0 but not new to mechanics as i have built and race a miata here in MN at the Brainerd Road Course.

Recently i purchased an 87 GT speed density car. It had work done to it previously witch was not ideal but for the price i could not pass it up plus it ran great.

The motor had been rebuilt 88k ago by the owner before the one i purchased her from along with adding:
cam
gears
cold air intake
msd coil
ford racing wires
motorcraft distributor
complete smog delete

Unfortunately i do not know what cam and what gears all i know is the speedo doesnt work any more and it idles a little high.

I drove the car cautiously for a week after purchase getting used to the quirks and driving a new car. It ran great started instantly and was happy as could be. Then on the way home from work she died while accelerating up a small hill. I could not get it started again the motor would crank but would not fire almost as if it was not getting gas.

Towed it home and checked fuel pressure at the schrader valve and got a low reading( i dont remember how low as i have been working on this problem for over a month now) I went and ordered a 255 walbro from summit racing and promptly installed it along with a fuel filter. After installing the new pump i still could not get her to fire. I put the car into diagnostic mode by jumpering the 2 ports together and all of a sudden it came to life but very very poorly. Like white smoke coming out of the tail pipes and the idle jumping around from 500 to 1500. I started testing power from the alternator because with the idle dropping so did the battery gauge. I was getting goofy readings at the alt and had it tested at oriellys and it failed. So i purchased a heavy duty 130 amp alt kit from LMR since from what i could tell it still had the low rated stock unit. I checked for vac leaks witch was easy since the egr was bolted off and nothing really running from the intake other than the PCV and Baro Sensor. This did not fix my problem.

Since then i have replaced:

Distributor
TFI Module
plugs
coil
IAC
Air charge temp sensor (i had a code for this witch is now gone)
O2 Sensors

I have inspected:

All grounds(that i know of)
Salt and pepper shakers
throttle body
relays eec and fuel (they both seem to be clicking on)
Compression check (I stopped cranking at 150)
TPS

The only codes i am getting at this point with the car running is 91 indicating a lean condition at the O2s on the drivers side and all the usual suspects for having an egr delete.

I have read, re read and read again the surging idle checklist along with the no start checklist and can not come up with a plausible solution or next step other than replacing the ecm. I will be attaching a link to what the battery and idle are doing shortly

Any help on the topic would be greatly appreciated as i am out of ideas

Here is the link to video of my idle and battery issue:
View: https://youtu.be/ooikcWL6Wu0
 
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With the EGR disabled, you should be getting more codes than just 91.

A couple of things come to mind:

Please review the procedure you used to pull codes.

There are more things that come to mind but those things are all contained within this check-list. Perform this procedure one line item at a time and you will see that it is not nearly as difficult as the initial impression you get from viewing the check-list:

https://www.stangnet.com/mustang-forums/threads/help-me-create-the-surging-idle-checklist.698148/
 
correct. I stated that i am getting codes from the egr delete in the 80s. 81-84 i believe. other than those there is nothing else to work off of as i am not going to re assemble to stock egr system. I have read the surging idle checklist and been crossing things off 1 at a time. I was under the assumption that i had covered all the bases from the list with no results. That is why i am on the forum. Is there something specific i missed? I will re read again
 
You replaced both o2 sensors but still get a lean reading on one side. I would test continuity across the injectors on that bank, you should see between 11.5 and 15ohm for each. An open or shorted reading means bad injector.

Doing a koer test should come up with a weak cylinder.
 
You replaced both o2 sensors but still get a lean reading on one side. I would test continuity across the injectors on that bank, you should see between 11.5 and 15ohm for each. An open or shorted reading means bad injector.

Doing a koer test should come up with a weak cylinder.

I will try that this evening
 
Two things come to mind. If you're fuel system is stock (lines and regulator) that 255 maybe over powering your FPR. I would double check your fuel pressure.

The other thing I would check is pin 46 on your ECM. It's the internal ground for all your sensors and gets damaged quite often. You can easily check it by putting a DVM between the pin on the large connector (EEC Test) that you use to pull codes with (gray/red wire on my car) and ground on the battery. If you read more than about 1 ohm of resistance you may have a problem and you'll need to pull the ECM and check the circuit board for a burnt trace.
 
Two things come to mind. If you're fuel system is stock (lines and regulator) that 255 maybe over powering your FPR. I would double check your fuel pressure.

The other thing I would check is pin 46 on your ECM. It's the internal ground for all your sensors and gets damaged quite often. You can easily check it by putting a DVM between the pin on the large connector (EEC Test) that you use to pull codes with (gray/red wire on my car) and ground on the battery. If you read more than about 1 ohm of resistance you may have a problem and you'll need to pull the ECM and check the circuit board for a burnt trace.


Thanks for the advice FPR tested fine no gas in the vac line. I don't know if my leads will reach all the way to the rear mounted battery ground though
 
Is 16.8 too much? Is that enough evidence to replace or repair the injector?

Not too far out of spec. Typical reading should be 14.4 ohms.

One thing that stands out is that you said you have a cam, but the car is speed density. This alone could cause the air/fuel mixture to never be right as the ecu simply cannot adjust for the aftermarket camshaft. Typically a cam swap on a 86-88 speed density car requires a mass air conversion. There are some exceptions, but if you start the car up and the idle is lumpy, I would bet that cam won't work well with SD.

However, the cam swap tells me the engine has been opened up, and it's possible there is a vacuum leak (internal or external) that suddenly occurred and is causing your issue. There is a procedure for testing for internal vac leaks that @jrichker has posted before. External leaks can be found with the standard methods of carb cleaner and bumped idles.

Run the cylinder balance test at the end of the code reading and make sure you get a code 9 (all good).

A 255 should still work well. The fuel system is a return style system so the excess will flow back to the tank in an endless loop. Fuel pressure should be 39psi vacuum off. When the car idles, it will drop to maybe 35psi or so, and then a blip of the gas should bump it up to ~39psi. You'll need a guage to confirm this of course.
 
Not too far out of spec. Typical reading should be 14.4 ohms.

One thing that stands out is that you said you have a cam, but the car is speed density. This alone could cause the air/fuel mixture to never be right as the ecu simply cannot adjust for the aftermarket camshaft. Typically a cam swap on a 86-88 speed density car requires a mass air conversion. There are some exceptions, but if you start the car up and the idle is lumpy, I would bet that cam won't work well with SD.

However, the cam swap tells me the engine has been opened up, and it's possible there is a vacuum leak (internal or external) that suddenly occurred and is causing your issue. There is a procedure for testing for internal vac leaks that @jrichker has posted before. External leaks can be found with the standard methods of carb cleaner and bumped idles.

Run the cylinder balance test at the end of the code reading and make sure you get a code 9 (all good).

A 255 should still work well. The fuel system is a return style system so the excess will flow back to the tank in an endless loop. Fuel pressure should be 39psi vacuum off. When the car idles, it will drop to maybe 35psi or so, and then a blip of the gas should bump it up to ~39psi. You'll need a guage to confirm this of course.

Thank you for the reply. If this is the case the car has been running for at least a year and the claim is 88k since the rebuild. Could a vac leak really take this long to show itself?

I have confirmed there are no external leaks. I guess a leakdown test is next? Maybe swap to maf any way shouldn't hurt anything right? I was told there was a cam but the guy didn't know which one as it was installed before he bought it. Maybe there was no cam and I was being lied to.
 
Thank you for the reply. If this is the case the car has been running for at least a year and the claim is 88k since the rebuild. Could a vac leak really take this long to show itself?

I have confirmed there are no external leaks. I guess a leakdown test is next? Maybe swap to maf any way shouldn't hurt anything right? I was told there was a cam but the guy didn't know which one as it was installed before he bought it. Maybe there was no cam and I was being lied to.


I wouldn't change anything right now. That will just add to the mystery since then you don't know if the maf upgrade worked properly or not. The car ran as is correct? Then it could run again without changing a thing.

I missed the white smoke part. Run a cylinder balance test through the ECU, and then do a compression test. Let's see if there's a huge misfire due to head gaskets
 
I wouldn't change anything right now. That will just add to the mystery since then you don't know if the maf upgrade worked properly or not. The car ran as is correct? Then it could run again without changing a

I missed the white smoke part. Run a cylinder balance test through the ECU, and then do a compression test. Let's see if there's a huge misfire due to head gaskets

I did do a compression test they all were 150+ except for 1 at 140. I will do the cylinder balance test
 
this just keeps getting weirder. As I am resetting the tps after restting the memory I get the car to run without the iab (this is new I had to crank the idle screw a ton but it finally idled on its own) shut off the engine like the instructions said to so I could check and adjust the tps voltage. Put the tps to spec then plug the IAB in and go to start the engine and it wont start. It turns but wont start. So weird. 5 minutes earlier it started on command and now it cranks but nothing else. Fuel pump turns on and pressure at the rail. eec relay clicks. Its like I'm back to square 1 before I got it running.
 
Cranks OK, but No Start Checklist for Fuel Injected 5.0 Mustangs model years 1986-1995

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 26-Jul-2017 to add fuse link diagram.

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, Crane, or other ignition box if present - Bypass it and return to stock configuration if possible. Do this as a temporary measure to eliminate it as a possible problem source.
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. Don’t replace the computer just because you don’t understand how it works. Computers seldom fail, it usually is a sensor or wiring problem that causes the problems.
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/blue 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.
See the Ignition switch wiring diagram for more information on the ignition wiring fuse link because it is the next thing to be tested. You will need a Multimeter or DVM and know how to use the Ohms function to check continuity between the red/green wire on the ignition coil and the red/green wire on the ignition switch. Make sure that the ignition switch is in the off position when you do the check. You should see less than 1 Ω (Ohm) between the red/green wire on the coil and the red/green wire on the ignition switch. More than 1 Ω means that the fuse link may have blown open and needs to be replaced. If you get 1 Ω or less means the fuse link is OK and the ignition switch is bad.

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 2-4 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?attachmentid=68357&stc=1&d=1322348015.gif


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.

64326


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.

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.
B.) Pull an injector wire connector off and look for 12 volts on the red wire when the ignition switch is on.
C.) 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.
salt-pepper-10-pin-connectors-65-jpg.68512

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


D.) 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.
E.) 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.
 
quick update. The TPS needed to be backed down to .91V to have it actually start. When it was at .99 it just cranked with no combustion. Still did not solve the crazy idle i will keep everyone posted as to what i find this evening.