Cadillac Repair: 1990 Cadillac Deville Ignition Problems, new distributor cap, cadillac deville

Question
I have a 1990 Cadillac Deville Sedan with a 4.5l engine with 200,000 miles on the clock.  A while ago the car started running rough. I replaced the spark plugs and spark plug wires.  The car ran better for a few days and then the problem returned, and seemed worse.

I checked the distributor and replaced the distributor cap and the rotor.  The coil seems to be fine as it generates a healthy spark. The electrical harness running through the distributor was in a bad state - the insulation around most the connectors fell apart as I attempted to verify the connections.  Since a new harness cost $194 and the controller $98 (from Cadillac), and the Hall Effect Switch was $118 (from Schucks), I pulled these parts from a junkyard 1992 Cadillac Deville Sedan 4.5l.

In all I replaced the harness, the Controller, and the Hall Effect Switch with the parts from the junkyard car, and it has a new distributor cap and rotor.  I took it for a test run and the car ran fine, no error codes.

Later the same day I ran it for about 50 miles and all appeared well, when the car suddenly turned rough again and stalled.  It showed error codes E12 (no distributor ref signal), E53 (distributor signal interrupt) and E97 (P/N to D/R @ high throttle angle).  After it sat for an hour, I cleared the error codes and it started fine, but I barely made it home with the car finally stalling in my driveway.  This time it only showed E53.

This morning I reseated the connections and drove the car for about 10 miles.  It runs fine when cold, but after 3 miles or so some roughness seemed to reappear.  I did not stall again and there are no more error codes, but the roughness (slight misfire?) seems to indicate to me that the underlying problem is still hiding out somewhere.

Any suggestions will be much appreciated.


Answer
If your engine roughness is at idle speed you need to perform the IDLE RE-LEARN PROCEDURE.

You will need simple electrical schematics, Test procedures and picture locations of the components within the system that is causing you problems of which can't be done on this website which only allows one picture. I do not have a website so you will have to e-mail: onlineautohelp@msn.com in order to obtain the information.