1988 Mustang Gt 5 Speed Misfiring And Popping With Headlights

TiffanyGT

Member
Feb 3, 2017
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Hello! I introduced myself briefly months ago. I bought this vehicle in August, drove it for a few months then garaged it throughout the winter. I'm just beginning to find out it has some "quirks". I had it on the road for the first time today since October. I have been starting it and idling it regularly throughout the winter and drove it up and down our street. I didn't have full coverage on it as I have the back seats out to address a convertible top leakage issue and we are getting ready to replace the quarter window motors. Yes, I drove around today without back seats and the rain channel removed. LOL! When I drove it previously one night in September I noticed a slight misfire when I had the headlights and the heat/blower on. It did it one night and I didn't notice it again. Fast forward to tonight.

The car drove like a dream all day today. I drove it around town, drove it on the freeway, etc. As I left to drive it home I put the headlights and the fog lights on (I do have moisture in one of my headlights). I had moisture in one of my previous Mustang's headlights and the headlights would randomly turn on and off. Tonight, as soon as I really stepped on the gas and went to shift into second it misfired and popped like crazy. I remembered that I thought the heater/blower had something to do with it months ago, however I didn't have it on tonight. It was light enough to safely drive without headlights so I turned them off. The misfiring and popping stopped even when I beat the :poo: out of it and shifted aggressively. I then stopped the car, turned both the headlights and fog lights on again and it misfired and popped like crazy. I then left the headlights on and turned off the fog lights. It still misfired, but not as badly with the fog lights off and only the headlights on. I know, less draw. It's had some quirks most of which seem to be electrical. I lose my stock radio presets upon the first start of the day. I also had it misfire a bit on the freeway doing about 65 when I put my windows up and down. The misfiring tonight was definitely worse with the headlights on than it had been previously. At that time, it seemed to be the heater/blower and drove fine with just the headlights on. I took it easy driving home with just the headlights on and it drove okay, but I could still feel it slightly misfiring when revving up to shift into second.

HELP! PLEASE!

Thank you!

Tiffany
 
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Coincidentally, I woke up this morning to find a puddle of water and battery acid under my car. The battery was bulging on one side. I was hoping there may be a connection between the battery/headlights and the misfiring/popping since right now it is only happening when I have the headlights on.

Nope. Just installed a new battery and took a test drive. Still misfiring and popping with the headlights on. Seems to drive fine without the headlights.

Ideas? One thing eliminated, about a million more to go :bang:.

Thank you!
Tiffany
 
Check voltage at the battery at idle, 13.5 volts and should jump up a little as rps increase. No less than 13.5 with headlights on at idle, again increases with rpms.
Also check your headlight switch connection, they are notorious for melting because of resistance, I thought there a upgrade thread here to fix that and the fog light problem but I will call on @jrichker for some insight, he's like a jeti information warrior.
 
Thank you for the reply. The plot thickens. I'm starting to become disheartened by the purchase of this vehicle.

I drove the car on a short errand after replacing the battery. I parked the car at the curb outside my house then realized I hadn't turned the wheels. I turned the key to start the car and OMG! She turned into Christine! I had no idea what was happening! She started making a loud noise from what sounded like the front right end. I turned the key in an attempt to shut her down and she wouldn't turn off. Kept shaking and and acting like she was trying to start when the car was already running (or was it). I had no idea what was going on so I kept my foot on the brake as I had a car parked in front of me (in hindsight I probably should have just gotten the hell out of the car). I started yelling as I had 2 people there working on another vehicle. They came out and yelled for me to shut it off. In my desperation, I pulled the key out of the ignition and held it up to show them I couldn't turn it off and the shaking, noise, attempts to turn on continued. Looking back now, that was kind of funny. They yelled for me to take my foot off the clutch. I guess in my panic and confusion I still had my foot on the clutch. The car then made a loud banging sound and the engine literally shook, you could visually see it kick to one side, then the car stopped and started smoking. I was crushed! We then disconnected the battery which was red hot.

You guessed it. Stuck starter. Related to the misfire and popping. Have no idea. High ho, high ho, it's off the LMR I go. Now, I'm paranoid this car may start on fire at some point as I seem to have some really wonky electrical issues going on.



Tiffany
 
Thank you for the reply. The plot thickens. I'm starting to become disheartened by the purchase of this vehicle.

I drove the car on a short errand after replacing the battery. I parked the car at the curb outside my house then realized I hadn't turned the wheels. I turned the key to start the car and OMG! She turned into Christine! I had no idea what was happening! She started making a loud noise from what sounded like the front right end. I turned the key in an attempt to shut her down and she wouldn't turn off. Kept shaking and and acting like she was trying to start when the car was already running (or was it). I had no idea what was going on so I kept my foot on the brake as I had a car parked in front of me (in hindsight I probably should have just gotten the hell out of the car). I started yelling as I had 2 people there working on another vehicle. They came out and yelled for me to shut it off. In my desperation, I pulled the key out of the ignition and held it up to show them I couldn't turn it off and the shaking, noise, attempts to turn on continued. Looking back now, that was kind of funny. They yelled for me to take my foot off the clutch. I guess in my panic and confusion I still had my foot on the clutch. The car then made a loud banging sound and the engine literally shook, you could visually see it kick to one side, then the car stopped and started smoking. I was crushed! We then disconnected the battery which was red hot.

You guessed it. Stuck starter. Related to the misfire and popping. Have no idea. High ho, high ho, it's off the LMR I go. Now, I'm paranoid this car may start on fire at some point as I seem to have some really wonky electrical issues going on.



Tiffany
I'm not a pro but I'd at least look at the ignition switch...they had a recall back in the day and are nortious for catching fire...mine melted into a big glob
 
You've definitely got some sort of electrical issues going on here. I guess the first question here is what sort of condition is the car in? Is it stock? Or has it been modified?

Bulging battery, hot battery, starter sticking, those are some interesting issues. What are the conditions of the battery terminals and other electrical connections?

Let me ask, how good are you at electrical troubleshooting? Do you have a digital multimeter? FIrst thing I'd have to you check is to go across the two terminals on the starter relay and test for continuity with the ignition off (and ignition wire removed). There shouldn't be any in which case I might suspect the ignition switch. If there is, then the relay may be bad.

ANy pics of underhood to try and see if we can pinpoint anything that looks wildly "wrong"?
 
You have pretty well singled out the ignition switch as one area of failure. With that in mind, here's some help.


Recall on Ford Ignition switches:

Revised 7-June-2014 to add Torx bit picture and source. Also added replacement ignition switch wiring pigtail picture, part numbers and sources.

Some of the symptoms of ignition switch problems are things that don’t work or are intermittent like radio, turn signals, wipers or heater.

There was a FREE recall on Ford ignition switches. They overheat and sometimes catch fire. That burns up the steering column and sometimes the car interior. Since this is very old information, you may not be able to get the switch replaced for free anymore. The auto parts stores sell the switches for $13-$15.

4.jpg


4.jpg


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While you are working on the switch, check the wiring and connector closely. A replacement connector with new wiring pigtails is available from most auto parts stores

AutoZone and Advanced Auto Parts have the same Part Number: 434 - may have to order, not always in stock

Advanced Auto Parts alternate part number: PT5534

20974527_bwd_pt5534_pri_larg.jpg


Saleen0679 was nice enough to dig this up for us awhile back: Replace a 1979-1993 Ignition Switch Assembly

Torx bit set from Advance Auto Parts

9021337_atc_ac571w1386_pri_larg.jpg


Autocraft torx bit set – have small hole in tip for tamper proof screws.
Part No. AC571/W1386 Cost approx. $12 +tax

Diagrams courtesy of Tmoss & Stang&2birds

Ignition switch wiring
IgnitionSwitchWiring.gif


Fuel, alternator, A/C and ignition wiring
fuel-alt-links-ign-ac.gif


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

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 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

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

O2 sensor wiring harness
http://www.veryuseful.com/mustang/tech/engine/images/mustangO2Harness.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 & pin out
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

87-92 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang87-92 PowerWindowWiring.gif

93 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang93PowerWindows.gif

Visual comparison of the Ford Fuel Injectors, picture by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/Ford_Injector_Guide.jpg
 
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Thank you for the info. I will try to answer your questions more in depth tomorrow.

I did want to pop on and say we have replaced the ignition switch. We were hoping that would solve all or some of the issues, but It didn't. We have also replaced the solenoid among a few other things which I will get into tomorrow. No change with the solenoid.

Have a good evening!
Tiffany
 
I'm hoping I attached this pic correctly. This is my Beauty. I have to get her running right. There is so much more good than bad in regard to this car.

The man I bought this car from kept extensive history, receipts, etc on it. I'll go through the info and hopefully I can share all or most of the mods that have been done to this car. He put a lot of money into it and he replaced much of the typical parts that go bad throughout the years. I live North of Seattle and I did drive this car home from South Oregon almost from the the CA border and it ran like a champ all the way home. No problems whatsoever. The problems started a few weeks later. He didn't drive it much and had it garaged.

I had a neighbor call me yesterday and tell me to "get my pretty little car off the curb" that there were a lot of people slowing down and stopping to look at it. We were out pulling the starter yesterday and 2 guys In a car turned around and sat at the curb across the street on their phones looking toward our curb, car and house. They were there for about 20 mins. Looked like they may have been taking pics. I stood in my garage and stared at them letting them know I was watching them and one of the little :poo:s waved at me. So, last night I blocked my Mustang in with 2 other vehicles so there was no way anybody could move it. I also laid on my couch in the living room with my window open staying up until it got light keeping her safe. The alarm isn't working right now. My wheels are expensive. I know, maybe crazy.....but dedicated.

I will gather as much info as possible about the car and mods as and post it. On the bright side, it's raining and I just went out and marked the areas where the water is dripping in under the convertible top with paint pen. That's something, I guess.
 

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All tucked in. :) The starter should be here by end of day tomorrow. Hopefully, that is all that's needed to get her back into the garage.
 

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Okay, so here it is........just the facts maam........

Parts that I have replaced since purchase August of 2016

Solenoid
Ignition switch (2nd replacement as it was replaced on recall as well)
130 amp Alternator/wiring harness
Battery cables positive and negative
Battery
Coolant reservoir/tank
Rear brakes and cylinders
Sun visors

Previous Owners Mods

K and M filter/stock cold air intake
Hurst shifter (24 years old)
3 piece American Racing Wheels/lowering springs
3 chambered Flow Master exhaust/cat back
Suspension Techniques (25 years old) with original struts/shocks


Currently has stock radio and after market alarm (read that alarms can cause electrical issues)

What I found in receipts (there were a few I couldn't read, but this is most of them)

EFI fuel pump 2013
filter
tank sending unit
filler neck seal
oil level sensor
oil level deal
mass air flow sensor and clean

O2 Sensor 2005
O2 Sensor
Diverter valve upstream/downstream
Diverter valve solenoid

Replaced fuel injectors and valve cover gaskets 2002

8 fuel inj 19lb 2002

Sensor assy-eh gas recirc 2001
sensor as-ego (heated)
valve and actuator asy

Clutch 2001

Radiator 2001

Pump assy exh a. 2000

Shifter 1991

Heater core 1994

Cat convertor 1994

There is a lot of documentation on emissions as this was a CA car.

One of the rear quarter window motors is not working properly. Motor worked and drive gear didn't when purchased. Motor started cutting out after a few weeks of driving. Maybe there is an electrical issue there?

We also increased the timing from 11 to 14 to see if the car would drive better or have additional pep. The misfire worsened after the increase, but I don't know if there could be any correlation. If we backed the timing off would the misfire be less like it was before the car was garaged? It is still at 14.

I also can't help but wonder if there is any correlation with the battery issue, starter issue and the new higher amp alternator and new wire assembly? The new alternator was installed in March and the increased misfire was present on the first drive (with headlights) a few days ago. I also had the starter stick and burn and the battery bulge and leak all over.

I ran an error code (paper clip) test when I first noticed the misfire. It threw no codes at that time. I am going to rerun the test.

I can snap a pic under the hood tomorrow and post.

Thank you everyone for your time and help!

Tiffany
 
Thank you for that info. Very important. I have forwarded it to the installer of the alternator. I am an assistant mechanic at this point, but learning a lot. I'll know tomorrow whether there was a problem with the wiring on the install. Definitely need to figure this out before installing the new starter and reconnecting the battery. Much appreciated!
 
@TiffanyGT

No code 11 (two flashes when the computer dumps the codes)? A perfectly functioning system will always get a code 11, it is the everything is OK code. The 11 code is computer passed its internal self test.
If you don't get an 11, you have computer or wiring problems.
Please check and repost.
 
"She's alive........aliiiiiiiiive"..........yes, gratuitous 80's movie reference.

We got the new starter installed and she's running again and safely settled into the garage for the night. We found that the solenoid relay switch was stuck in the closed position. We tapped it and it released. This solenoid was replaced a few months ago. What would cause it to stick? We double checked the alternator and the voltage. Everything looks good. This is the alternator that was installed so the wiring install differed from the link posted here last night. Unfortunately, no change in regard to the misfire and popping. I still have misfire when the headlights are on.

https://lmr.com/item/PA-16196B1/87-93-Mustang-130-Amp-Alternator

I ran the computer diagnostic test and the codes are as follows. I know that the 88 throws 2 digit codes. I am going to post the codes exactly as they were noted. jrichker mentioned a code 11 meaning the computer is a-okay...I'm not sure if an 11 was flashed.

Key On.....

4
4

4
4

Key off....

Two really fast flashes.......does this count as an 11? Please?

Then

6
7

6
7

1 (there was a single one that flashed here)

9
6


9
6

I've looked up the codes 44, 67, and 96 and am unsure of exactly what they may be? I'm also not sure if the two quick flashes (faster than all the rest) at the start of the key off test means 11?

Good evening!

Tiffany
 
The codes 44 and 67 won't cause the misfire condition you are having problems with, but the code 96 could be the cause.


Codes 44 & 94 - AIR system inoperative - Air Injection. Check vacuum lines for leaks, & cracks. Check for a clogged air crossover tube, where one or both sides of the tube clog with carbon.

attachment.php?attachmentid=50636&d=1180923382.gif


Revised 21 Sep 2012 to correct the description of the process that sets the code and include Thermactor Air System diagram.

If you have a catalytic converter H pipe, you need to fix these codes. If you don't, then don't worry about them.

Code 44 passenger side air not functioning.
Code 94 driver side air not functioning.

The TAD solenoid/TAD diverter valve directs smog pump output to either the crossover tube attached to the cylinder heads or to the catalytic converters.

The O2 sensors are placed before the catalytic converters, so they do not see the extra O2 when the smog pump's output is directed to the converters or the input just before the converter.

The 44/94 code uses the O2 sensors to detect a shift in the O2 level in the exhaust. The smog pump provides extra air to the exhaust which raises the O2 level in the exhaust when the smog pump output is directed through the crossover tube.

When there is an absence of increase in the O2 levels when the TAD solenoid/TAD diverter valve directs air through the crossover tube, it detects the lower O2 level and sets the code.

Failure mode is usually due to a clogged air crossover tube, where one or both sides of the tube clog with carbon. The air crossover tube mounts on the back of the cylinder heads and supplies air to each of the Thermactor air passages cast into the cylinder heads. When the heads do not get the proper air delivery, they set codes 44 & 94, depending on which passage is clogged. It is possible to get both 44 & 94, which would suggest that the air pump or control valves are not working correctly, or the crossover tube is full of carbon or missing.

Testing the system:
Note that the engine must be running to do the tests unless stated otherwise. For safety’s sake, do test preparation like loosening clamps, disconnecting hoses and connecting things to a vacuum source with the engine off.


Disconnect the big hose from smog pump: with the engine running you should feel air output. Reconnect the smog pump hose & apply vacuum to the first vacuum controlled valve: Its purpose is to either dump the pump's output to the atmosphere or pass it to the next valve.

The next vacuum controlled valve directs the air to either the cylinder heads when the engine is cold or to the catalytic converter when the engine is warm. Disconnect the big hoses from the back side of the vacuum controlled valve and start the engine. Apply vacuum to the valve and see if the airflow changes from one hose to the next.

The two electrical controlled vacuum valves mounted on the rear of the passenger side wheel well turn the vacuum on & off under computer control. Check to see that both valves have +12 volts on the red wire. Then ground the white/red wire and the first solenoid should open and pass vacuum. Do the same thing to the light green/black wire on the second solenoid and it should open and pass vacuum.

Remember that the computer does not source power for any actuator or relay, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.

The following computer tests are done with the engine not running.
The computer provides the ground to complete the circuit to power the solenoid valve that turns the
vacuum on or off. The computer is located under the passenger side kick panel. Remove the kick panel & the cover over the computer wiring connector pins. Check Pin 38 Solenoid valve #1 that provides vacuum to the first Thermactor control valve for a switch from 12-14 volts to 1 volt or less. Do the same with pin 32 solenoid valve #2 that provides vacuum to the second Thermactor control valve. Turning the ignition to Run with the computer jumpered to self-test mode will cause all the actuators to toggle on and off. If after doing this and you see no switching of the voltage on and off, you can start testing the wiring for shorts to ground and broken wiring. An Ohm check to ground with the computer connector disconnected & the solenoid valves disconnected should show open circuit between the pin 32 and ground and again on pin 38 and ground. In like manner, there should be less than 1 ohm between pin 32 and solenoid valve #2 and pin 38 & Solenoid valve #1.

The following computer tests are done with the engine running.
If after checking the resistance of the wiring & you are sure that there are no wiring faults, start looking at the solenoid valves. If you disconnect them, you can jumper power & ground to them to verify operation with the engine running. Power & ground supplied should turn on the vacuum flow, remove either one and the vacuum should stop flowing.

Typical resistance of the solenoid valves is in the range of 20-70 Ohms.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif

If you have a catalytic converter H pipe, you need to fix these codes. If you don't, then don't worry about them



Code 67
Revised 18-Mar-2017 to include warning about the necessity of having a 5 speed O2 Sensor wiring harness when bypassing the wiring for test purposes

Cause of problem:
Clutch not depressed (5 speed) or car not in neutral (5 speed and auto) or not in park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code will prevent you from running the Key On Engine On tests.

External evidence from other sources claims that a code 67 can cause an idle surge condition. Do try to find and fix any issues with the switch and wiring if you get a code 67.

What the NSS (Neutral Safety Switch) does:
5 speed transmission: It has no connection with the starter, and the engine can be cranked without it being connected.
Auto transmission: It is the safety interlock that prevents the starter from cranking the engine with the transmission in gear.
What it does for both 5 speed and auto transmission cars:
The computer wants to make sure the A/C is off due to the added load on the engine for the engine running computer diagnostic tests. It also checks to see that the transmission is in Neutral (5 speed and auto transmission) 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 following is for 5 speed cars only. Do not do this unless you are sure that you have a 5 speed O2 Sensor harness!!!! Smoke, sparks and expensive pain in the wallet may ensue if you don’t.
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!!!

a9x-series-computer-connector-wire-side-view-gif.71316




Code 96 for 86-90 model 5.0 Mustang – KOEO- Fuel pump monitor circuit shows no power - Fuel pump relay or battery power feed was open - Power / Fuel Pump Circuits. The fuel pump lost power at some time while the ignition switch was in the run position. The main power feed to the pump is what is losing power.

Look for a failing fuel pump relay, bad connections or broken wiring. The fuel pump relay is located under the passenger seat. On Mass Air Conversions, the signal lead that tells the computer that the fuel pump has power may not have been wired correctly.
See http://www.stangnet.com/tech/maf/massairconversion.html

Look for power at the fuel pump - the fuel pump has a connector at the rear of the car with a pink/black wire and a black wire that goes to the fuel pump. The pink/black wire should be hot when the test connector is jumpered to the test position. . To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground.
attachment.php


86-90 Models:
Using the diagram, check the red/black wire from the fuel pump relay: you should see 12 volts or so. If not, check the inertia switch: on a hatch it is on the drivers side by the taillight. Look for a black rubber plug that pops out: if you don't find it, then loosen up the plastic trim. Check for voltage on both sides of the switch. If there is voltage on both sides, then check the Pink/black wire on the fuel pump relay: it is the power feed to the fuel pump. Good voltage there, then the fuel pump body to tank wiring harness connector is the likely culprit since it is getting power. No voltage there, check the Orange/Lt blue wire, it is the power feed to the fuel pump relay & has a fuse link in it. Good voltage there & at the Pink/black wire, swap the relay.

Keep in mind that the relay wiring and socket can also cause intermittent problems. Clean the relay socket with non-flammable brake parts cleaner or electrical contact cleaner. If you find damaged wiring at the relay socket, replacement pigtail socket assemblies are available at the auto parts stores. Be sure to solder the wires and cover the solder joints with heat shrink tubing if you replace the relay socket.


fuel-pump-wiring-89-90-5-0-mustang-jpg.55493