Questions about car dying while driving.

5point0dude

Member
Sep 5, 2007
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Hey, everyone. My 1991 5.0 LX has been having some problems lately. First, I'll be driving around cruising at a constant speed when suddenly the car dies for a split second, the tach goes to 0, and then right back up to where it was before it died. It feels like the engine completely shuts off then comes right back on. The headlights, dash lights, and radio do not turn off. It does it a couple times within a few minutes, then doesn't do it again the rest of the time I'm driving. It has been doing this for a few weeks, every time I drive it. I cleaned the air filter, throttle body, MAF, and IAC module, but the problem still remains.

Second, the car has had trouble starting a couple times. It cranks for awhile then starts up. I'm guessing the starter is going out, but I'm thinking it might be related to the first issue also. Twice, I was slowing down for a red light and the car died. I cranked it and it started up after about 10 seconds. Also, the plugs, plug wires, fuel pump, and fuel filter were all changed less than a year ago. Any answers would be greatly appreciated, I'm stumped right now. Thanks.
 
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jrichker

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Dump the codes and see what the computer has to say. No codes and you get an 11 when you dump them, then replace the ignition switch if you haven't already done it.

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.

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



Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.

Underhoodpictures007-01.jpg


Underhoodpictures010.jpg


If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.


WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, and clutch (if present) is pressed to the floor, and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see Equus - Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.
Or for a nicer scanner see http://www.midwayautosupply.com/p-7208-equus-digital-ford-code-reader-3145.aspx– It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.
 

Bullitt95

10 Year Member
Jun 13, 2007
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www.angelfire.com
I'll be driving around cruising at a constant speed when suddenly the car dies for a split second, the tach goes to 0, and then right back up to where it was before it died. It feels like the engine completely shuts off then comes right back on. The headlights, dash lights, and radio do not turn off. It does it a couple times within a few minutes, then doesn't do it again the rest of the time I'm driving. It has been doing this for a few weeks, every time I drive it.

Second, the car has had trouble starting a couple times. It cranks for awhile then starts up. I'm guessing the starter is going out, but I'm thinking it might be related to the first issue also. Twice, I was slowing down for a red light and the car died. I cranked it and it started up after about 10 seconds.
Your problem is 99.999% likely to be either a bad PIP sensor or a bad TFI module. These are common problems in Foxes 'cause they're distributor mounted and sensitive to heat soak. The best solution is to replace the whole distributor with a new Motorcraft unit, especially if yours is the 20-year-old original.
 

jrichker

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Your problem is 99.999% likely to be either a bad PIP sensor or a bad TFI module. These are common problems in Foxes 'cause they're distributor mounted and sensitive to heat soak. The best solution is to replace the whole distributor with a new Motorcraft unit, especially if yours is the 20-year-old original.
Well intentioned but bad advice. TFI & PIP sensor problems usually either kill the engine until it cools off or cause a random miss that increases in frequency as the operating temperature goes up. They don't shut off and turn back on again like flipping a switch or loose connection. A reman distributor is $55-$75, a TFI is $30-$50. A paper clip to dump the codes and see what the computer think is wrong is less than a nickel.

Diagnose the problem in small simple and inexpensive steps. Ignition switches are a known problem area. It sounds like you are losing power to the computer & ignition and then it comes back on. That's why I recommended that you dump the codes and replace the ignition switch if you didn't find anything significant.
 

Bullitt95

10 Year Member
Jun 13, 2007
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Your diagnostic advice is correct jrichker and I agree that the OP shouldn't just throw parts at the problem, but the symptoms the OP described are exactly the same as what I experienced when my TFI module bit the dust early last year, and I didn't have any codes at all.
The PIP sensor and the TFI module are indeed cheap to replace individually but a 20-year-old distributor is likely to have advanced wear of the shaft bearings, so it's a false economy to do nickel-and-dime parts replacements (I've been there so I know). Reman distributors are cheap but have uncertain reliability so it's better to pay more and buy a brand new one with PIP sensor and TFI module attached. That kills three birds with one stone.
 

5point0dude

Member
Sep 5, 2007
51
1
9
Thanks for the replies, guys. I'm going to try to dump the codes to see if I can get something. The distributor is the original unit, and even though it might not be the problem, I've been thinking about replacing it anyways.
 

5point0dude

Member
Sep 5, 2007
51
1
9
And it did it again last night. I was driving home and slowing down for a red light, and the car died. Took a lot longer to re-start it. I was sitting there for about a minute trying to get it to crank over and it finally did.
 

mike0227

Member
Dec 19, 2004
53
0
7
Houston Texas
Car dies

Had the same problem with car dieing. I had just bought a well used 1990 in Los Angeles and was driving to Houston through the Nevada desert when it just died going down Baker grade in 105 deg weather. Coasted to rest stop and began looking for problem and found nothing. After car cooled started up and drove to Vegas and changed fuel filter then it did it again.

For the rest of the trip it only did it 2 more times and has not done it since. If I ever go cross country with the old fox the TFI will be replaced and will cross my fingers.
 
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