1986 Ford Mustang Engine Dies when it begins warming up.

Tiny
JWOLFF
  • MEMBER
  • 1986 FORD MUSTANG
  • 8 CYL
  • 2WD
  • MANUAL
  • 151,000 MILES


http://www.2carpros.com/forum/automotive_pictures/142503_DSC_1043_1.jpg



This is a factory 5.0 sefi late year 86 lx mustang with a manual trans. I have added the mass air and computer from a 89 automatic mustang GT in the past. The problem just started recently, the car starts and runs fine cold. After it is driven enough for the temp gauge to hit about 1/3 the car starts cutting out. If i pull over and continue to baby it and do anything to keep it running, eventually when it reaches normal operating temp it goes back to running normal. After troubleshooting it a bit, now it has gotten so rough when it's displaying this problem that I am unable to keep it running long enough to get to that warm spot that keeps it running. It sputters, pops, even sounds like backfiring when i am giving it gas to keep it running. When it is parked in the garage, and warm enough to be problematic, if the car is started and no gas given, it will run for 2-3 sec and die. I have tried unplugging several items on the motor to see if there is any difference, and so far I have found none. These items include, IAC, Block temp sensor, EGR, MASS sensor. Any suggestions would be great.

Thanks

update.....
I replaced the IAC and it runs better during the warming period, but it still dies if left to idle and stumbles a bit if the motor is running at a cruising speed. It is less violent now when it dies, so it's better, but not fixed. Guess tomorrow I will replace the temp sensor. Codes I pulled from the computer after a reset and running until warm are as follows;

6 7
Improper signals are being
received from either the
Neutral Drive Switch (NDS),
Neutral Gear Switch (NGS),
Neutral Pressure Switch
(NPS), Clutch Switch (CS),
Manual Lever Position
(MLP) sensor or Air
Conditioner Clutch (ACC).
or,
Air Conditioner (A/C) on
during Self-Test.

8 1
Thermactor Air Diverter
(TAD or AM-2) solenoid:
circuit failure.
or,
Electro-Drive Fan: circuit
failure.
or,
Intake Air Control (IAC)
valve: circuit failure.
or,
Boost solenoid – circuit
failure.

8 2
Thermactor Air Bypass
(TAB or AM-1) solenoid:
circuit failure.
or,
Electro-Drive Fan: circuit
failure.
or, Electronic 4-Speed
Overdrive Automatic
Transaxle (E4OD):
Transmission Oil
Temperature (TOT) sensor
– signal voltage is too high.

9 5
Thermactor Air System problem – right (passenger)side air flow always upstream.
or,
Fuel Pump Monitor (FPM)
signal – indicates circuit
problem.
Do you
have the same problem?
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No
Sunday, January 13th, 2008 AT 11:14 AM

6 Replies

Tiny
JACK42
  • MEMBER
Sounds like the shorter list is the codes it doesnt have. Lol. Clear the codes an drun it to see what comes back. THis could very well help. Also install a manual fuel pressure gauge. WHen it dies test the spark quality
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Monday, January 14th, 2008 AT 5:03 PM
Tiny
JWOLFF
  • MEMBER
Thanks, for responding.

Here is where I am so far. I pulled the ground from the batt and left it overnight (As far as I know that resets the computer) and before running the car it gave all the same codes listed and one about the motor temp not in range (probably because the motor was still cold). I am doing a stored codes test without the car running, I haven t tried the running test yet. If I am resetting the computer properly I am now wondering if these codes are showing up because the computer is for an 89 automatic and I have it in a 86 manual multiport. I have had very little trouble with the car since I did the computer swap years ago and have never pulled codes from it, so I have no baseline to refer to. Unfortunately I am unable to locate the original speed density computer at the moment.

I purchased an attached a fuel pressure gauge and the results are as follows.
Key on motor off, 40 psi
Key on motor running 37 psi.
When the motor is warm enough to begin displaying the problems, when running its 37, when it stops it goes up to 40 and the pump shuts off shortly after and the pressure stays at 40.

I have now replaced additional parts yet the problem remains. I have replaced the EGR Valve, and cleaned the holes in the throttle body that correspond, because they were very dirty with carbon. I replaced the manifold temperature sensor above cylinder 5.

One last bit for tonight, this car has sat in my driveway for 9 years now. I put 100k miles on it when I was younger and after breaking 3rd gear it was parked and a new daily driver purchased. I started it occasionally and moved it around the driveway after the trans was replaced, but never plated it and drove it on the street. I recently decided that I needed to paint it and put it to use or move it on. This is now it's 2nd week with plates. I drove it about 70 miles the 1st day I braved taking it out and it drove fine for the first 1/2 of the day and then almost didn't get home without a tow truck. It's funny that it did work, but now it doesn't.

I am unsure of how to test the spark quality. Is this just pulling one plug wire, putting a plug in it, and looking to see if it's blue or yellow spark?

Thanks for the help again.
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Tuesday, January 15th, 2008 AT 11:25 PM
Tiny
JACK42
  • MEMBER
Go buy an inexpensive spark tester so you dont get zapped. Check spark quality out ofthe coil and at eh spark plugs. Most of your codes pertain to the trans. Have you inspected the wiring harness carefully, might have been chewed on by rats, seen it more than you would believe.
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Wednesday, January 16th, 2008 AT 7:18 AM
Tiny
JWOLFF
  • MEMBER
I got a spark tester that simulates a spark plug with variable gap and unplugged one of the plugs without the motor runing to setup the test. The spark color with the engine running was a bluish orange and seemed in time with the motor, it stayed in time along with the cutout and when the motor dies the spark died also. I could only test the spark from the coil without the motor running, and simply cranking and that seemed to work fine.
I have not inspected the wiring under the car, from the top of the engine bay and inside the car seem fine.
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Wednesday, January 23rd, 2008 AT 10:52 PM
Tiny
JACK42
  • MEMBER
Dead and still has spark? Now need to test injector pulse with a noid light to see if the PCM is firing them, have fuel pressure?
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Thursday, January 24th, 2008 AT 7:32 AM
Tiny
JWOLFF
  • MEMBER
I replaced the ignition control module and put a lot of heat sink compound on the back of the module and now the vehicle has returned to fully functional. Thanks for your help.
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Thursday, January 31st, 2008 AT 8:50 AM

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