[awbazar]

Having considered a full Helm set for this car and not liking the hundreds of $ to acquire, I found some code listings and details on various internet sites. Never having had a MIL code show up on the "check engine light" for years, the beast now publishes daily new codes for my entertainment.

Can anyone direct me to a free or moderately inexpensive source of diagnostic trouble codes for a 93 Taurus? The latest mystery code kicked out was 539 which doesn't appear on any list I have seen. The prior favorite was 327. According to the information which I have, this is a "differential pressure flow exhaust circuit", DPFE, below minimum voltage. I cleaned the EGR valve which seems to operate ok, and found a broken vacuum hose to another sensor but can't get rid of 327.

The car seems to run as well as it ever did even with this 327 code and has no problems that I can detect. No rough idle, it has good acceleration, gets its typical 22 mpg, for a 3.8L, on trips with a lead foot driver, etc. Any clues will be immensely appreciated!

[Kevin45]

Here is a list of the codes. 539 is A/C on during test, 327 is EGR. I know on GM the computer has to be cleared with a scan tool. I don't know about Fords though. You might try having it done (clearing the computer) with a scan tool instead of just unhooking the battery. I am assuming you just unhooked the battery to clear the codes although I may be wrong. http://www.denniswolfe.com/Taurus/Re...ide/Repair.htm

[awbazar]

Thanks Kevin 45, the A/C was on when I did, the test which explains the 539 MIL code. I did try dumping the MIL codes which involves removing the jumper from the diagnostic connector once the MIL codes start to blink. To dump all memory called KAM, (keep alive memeory), I have to remove the negative battery cable for 10 minutes too. This dumps everything and requires running the car for 10 miles to relearn new settings for the combustion system. Thanks for the tip. Now I'm back to my EGR related solitary problem...327.

[dmorris1200]

Ford has used various types of sensors to monitor EGR operation. A code for this monitoring system doesn't necessarily mean that the EGR isn't working but possibly just the sensor that monitors the EGR is faulty. On some systems like the older 4.9EFI truck engines like in a 90 F150 Ford used a plastic sensor that was screwed on top of the EGR valve. Most cars in the 90's used either a PFE or a DPFE system. The DPFE was usually rectangular in shape and had two special heat resistant hoses that went to two vacuum nipples in the EGR tube which runs from the EGR valve to the exhaust pipe/manifold. When the EGR opened the DPFE sensor would register a pressure change in the EGR tube and tell the PCM the valve was working. These sensors often go bad due to condensation in the sensor through the hoses. The PFE is usually smaller and often plastic with only one vacuum line going to it. Some of the newer DPFE's are now smaller also but still have two vacuum lines. These sensors are usually inexpensive and only a few minutes to change. There are ways to test the sensor with a service manual or you could just try changing it and clear the PCM code.

PS. If you ever chnage one of these sensors and the hoses crack you must use Ford's special heat resistant hoses and not regular vacuum lines.

[awbazar]

Thanks dmorris1200 for the comments about the various sensors on Ford EGR systems. I agree that it seems likely that I have a sensor failure to perform rather than a "real problem" with the EGR system on this 1993 Taurus GL. My next step will be to observe the voltages and do some experiments to pinpoint the item most likely needing replacement. Thank you for the ideas.