Hard to start 92 GT

Have you pulled codes yet? Has the IAC been replaced or cleaned lately?

I would think your IAC is bad or on its way out. When you put the other IAC and said it didnt really change anything. Did you try to start it in the morning or the 1st time in the day or just swap it out and started it

any chance it could be moisture in the dist cap? on the colder day there could have been less humidity in the air to get into a cracked cap. just throwing out an idea. had a similar problem once. A buddy told me to change the cap & rotor. It fixed mine.

The backfiring is due to a lean mixture problem or vacuum leak. Dumping the codes will spot ACT and ECT problems IF you dump them on a warm engine.

Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 19-May-2009 to update drawing for dumping the codes on 86-88 Mustangs with no check engine light.

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.

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

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 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.

Here's the link 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.

See Troublcodes.net Trouble Codes OBD & OBD2 Trouble Codes and Technical info & Tool Store. By BAT Auto Technical





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.

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.

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.

FWIW, you don't have a MAP sensor per se (the parts store guys might not list a MAP for your '92).

You might want to be sure the BAP's electrical connector is seated and check the TPS baseline. If the latter is reading a bit above or below 1.0V, that can generate a code. The issue in such a situation can sometimes be resolved without the need for a new component.

List the code numbers the code dump gave you. I have 5.0 Mustang specifc code definitions that tell you what's wrong and how to fix it. That can save you lots of $$$, because sometimes it is an adjustment or wiring problems and not a faulty sensor.

Check ECT.

One way I did it was to dump the codes on a stone cold engine. I usually got an ECT out of range code on a cold engine. Once I was working on a guys' truck exhibiting similar symptoms and was getting a code 11 (actually 111 on that particular deal...3 digit) meaning all clear but the engine was ice cold so it should have dumped a 116. Found sensor wire was cut due to engine install from previous owner...fixed the wire...cold naturedness and backfiring was gone. Also was getting a 116 on a cold engine just like it should have. That was a '95 F150 with a 5.0 and a M5OD-should be same principle.

Just a thought.