more weird problems....grrrrrrr

Use a vacuum gauge to determine if there is a leak - you should see 16.5"-18" of vacuum at 650-725 RPM. Use motor oil in a squirt can and squirt any suspect areas. The engine will change speed if the leak tries to suck up the oil. Do not use flammable liquid or propane to find leaks. A flash fire is a good hair removal method, but it is also painful and costly.. Ask Richard Prior about that...

No vacuum leaks found? Then dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

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.


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.

It is quite possible that your barometric pressure sensor is giving a false reading. Your car would misfire roughly until the EEC went into closed loop mode, after that it would adjust itself. i would recommend checking that.

so the coolant stays at 140 all the time even after runnin for a while? Is the top radiator hose warm? howd you check the sensor, ohmeter?

Get that working properly first before trying to fix the missing problem....you should at least have a thermostat, I would put in a 180 the lowest, or a 195.

randyb1976 said:

the hose gets warm but not hot...pulled the tsat out tonight and i had to really push hard to get the spring to move..like it was stuuck tight... also on the intake at the front there is a sensor that a little elbow goes on..believe its for the gauge...there is also one on the rear of the intake but no wire is on it...found an orange wire that looks like it should go there but someone splice it to a ground...does this sound right?

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If the front sensor looks stock, and the stock wiring (with the little rubber elbow) is there, that's for the stock gauge. The rear port originally had a square headed plug but it sounds like someone put an aftermarket sender there and then removed the gauge. Note that the rear port sucks for accuracy. I would put the inaccurate stock sender back there and lengthen the wire. Then put an aftermarket gauge's sender in the front (originally) stock location.

The orange wire is probably your HEGO ground, which should be grounded to the intake or head.

randyb1976 said:

the senser n the rear looks just like the front...if that isnt used for anything ill just let it alone..... where is the barometric pressure sensor located??

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What year of stang are you working on? Note electrical mods like mass-air conversions, etc.

The BAP is on the firewall, It's a dark rectangular looking box.