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.
See
http://www.troublecodes.net/Ford/
OR
See
http://www.mustangworks.com/articles/electronics/eec-iv_codes.html
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.
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.
For those who are intimidated by all the wires & connections, see
http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.
Or for a nicer scanner see
http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.
My capri is having issues for the 3 monthes. I bought it from this guy that had it sitting for 2 years. His son wrecked the car. So I fixed the body damage. It ran perfect until the water pump failed. It ran hot. I replaced the water pump and while I was in that area I replaced the timing chain. Well it didnt run to well it was hesitating and lack power. Checked timing and its correct. also it started to run hot so I replaced the radiator and thermostate which made no differance. Then I started replacing all the fallowing parts. Coolent temp sensor, MAP and, Idle position sensor. Every time I replaced something it seemed to run slightly better and run alittle cooler. I checked the catilitic converter and found that the H pipe was gutted. So I decided to disconnect the O2 sensors which made a huge differance. It had less hesitation and had alittle bit more power and, ran even cooler. So I ran it about a month with out them connected. I checked the compression which in all cylinders average of 170. Well the other day I bought O2 sensors and put them on. Car runs just like it did when I had the old ones connected. The coil checks ok too and coolent level is never dropping so I dont think Im leaking coolent into the cylinders. The spark plugs indicate that it runs slightly rich and hot but ok other than that. Could the computer gone bad?
Plus I checked fuel pressure and that checks ok at idle and driving.
