Engine Engine Revving On Its Own (burning Out My Clutch!)

XDIME03

New Member
Apr 18, 2015
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Hello all. Any help would be appreciated. I have a 1992 LX 5.0. When I start cold runs great drives good. After I drive for 15 mins or so when I clutch the rpm's jump up to 2k. Then after it starts that if I shut the engine off and it may restart its ok for a few minutes. Sometimes it does not want to restart as if the battery was dead. After sitting and cooling for a few minutes it will start back up again. Seems like something is getting hot. I was told possible iac valve so I replaced it but same condition. Not sure where to go from here.
 
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Would need to confirm engine temp sensor input, but along with your hard hot crank complaint I'm thinking you should start with verifying your battery power and ground connections especially at the starter and engine. Also the ground from the negative to the body as well as the ground strap from block to firewall. Also check the PCM connector for corrosion.
 
Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.

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.

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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.

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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.

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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.

Your 86-88 5.0 won't have a working Check Engine Light, so you'll need a test light.
See AutoZone Part Number: 25886 , $10
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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) Equus - Digital Ford Code Reader (3145It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $22-$36.
 
Clean your throttle body and IAC while you're at it.....and break out the brake cleaner and start spraying around the manifold, throttle body and vacuum hoses looking for vacuum leaks.

All free and easy to do.
 
my 93 coupe has the same problem iv replaced the idle air control and throttle position sensor and still nothing so dont waste your money on these parts if you find out what your problem is id greatly appriciate if youd share what fixed it with me!
 
most hot start issues with ford are the tpi module. From my understanding. I bought a napa tpi module and whenever i hit the clutch pedal the driver window would roll up. For some reason the only tpi module that works on my car is the one that came on my mallory distributor. motorcraft tpi fried my ignition coil in about 1 minute of the car running.

Edit: 93 5.0
 
I don't know how "stock" your car is but i have a chip and my car doesnt dump the timing when i press in the clutch. My rpms stay high right after i press in the clutch. If i wait for 5 or 10 seconds the rpms come down.