EGR problem or not? Idle issue

Dump the codes and see what the computer says is wrong. EGR codes will come up as code 3x.

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.

Hmmm. kind of sounds like an EGR position sensor because opening the EGR helps it idle, which is rare, because that will usually stall a vehicle. The computer thinks the EGR is open, therefore compensates timing and fuel, causing it to stall. The EGR is probally mostly clogged up as well becaues a wide open EGR will usually stall a vehicle fast.

90mustangGT said:

Hmmm. kind of sounds like an EGR position sensor because opening the EGR helps it idle, which is rare, because that will usually stall a vehicle. The computer thinks the EGR is open, therefore compensates timing and fuel, causing it to stall. The EGR is probally mostly clogged up as well becaues a wide open EGR will usually stall a vehicle fast.

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You are right about that. One of the Key On Engine Running tests opens the EGR and watches for the RPM's to drop. That's how the computer can tell if the EGR is opening while it is in test mode.