1991 eighty-eight Help with Codes Please

The SES light on my '88 Royale 3.8L 138k miles came on. Car starts and runs OK, though feels a little rough at idle (not sure if this is real or my imagination...my better half thinks it is a little rough idle too, making me really doubt myself...). Checked trouble codes and got 63. At AutoZone they told me the code is for Manifold Absolute Pressure (MAP) and printed me a few pages describing it. The AZ paper indicates it is used on 1996-99 models. I don't see one on my '91 although the Haynes manual for '85-2000 Buick Olds Pontiacs mentions and pictures a location for older models as well as a picture for '96-later models. The Vehicle Emission label on the car does not show a vacuum line going to a MAP? The Haynes bok has code 63 also as "(MAP) sensor volatge high (low vacuum detected)." However, when I searched this forum, code 63 has been described as EGR.

Can someone explain which code decription is correct for this car?
If the code is for the MAP, where on this car do I find it?
Any suggestions on how to diagnose why the SES came on?

Sorry for the long note, and Thanks for any help!

Steve

Lots of mis- info out there. There is no map on this engine, there is no listed code 63 either. The engine has a maf sensor. AZ is not the place to have the codes scanned, you are better off jumping the a and b terminals and counting the flashes, the 2 top r/h ports on the dlc. Check this link. http://www.troublecodes.net/GM/91_38C.shtml

Lots of mis- info out there. There is no map on this engine, there is no listed code 63 either. The engine has a maf sensor. AZ is not the place to have the codes scanned, you are better off jumping the a and b terminals and counting the flashes, the 2 top r/h ports on the dlc. Check this link. http://www.troublecodes.net/GM/91_38C.shtml


hmmm....AZ did not do the scan. I did, reading the flashes after jumping the 2top r/h ports on the dcl, and I definately got 63 after getting a 12 (12 indicates start of diagnostic mode according to the Haynes manual). So now what? Any help appreciated!

Do a full scan on a legit scanner and see what you get, the complaint of a little rough is too vague without additional diagnostics.

I replaced a few well-worn vacuum hoses and fiddled with the EGR (cleared gunk build-up from the solenoid springs) then pulled the negative battery cable to clear the codes. After reassemble and starting the engine the SES was off. I'll reply again if it comes back on while driving. But appears good for now.

Code 63 is exactly that... Its an EGR circuit fault... with the codes gone, and if you have driven the car and the light has not come back on you may be fine.. If the SES come back on check the codes and see if the 63 returns..