Northstar Engines and System Technical Discussion Discussion, 94 concours, test your knowledge in Cadillac Engine Technical Discussion; Hey Guys, lookin for a little help. My problem is after car reaches full operating temperature it begins to shudder ...
Hey Guys, lookin for a little help. My problem is after car reaches full operating temperature it begins to shudder or miss intermittantly. starts out very slight and becomes gradually worse but continues to be intermittant. went to my local dealership and they diagnosed my 94 concours with a bad icm said 800 bones to fix, i said thats too much ill take it home. took it home and put in a used icm and had identical problem. talked to tech and he said he was just going off of the codes - po23 electronic spark timing (est) signal problem (egr). po25 (ignition control module ) 24x reference low. and po83 crankshaft to ignition module failure. he said he never cleared codes these were history codes. I then entered this web site and began reading. I cleared codes and did a snapshot and got the po25 code again. I suppose the other codes may come back as i just did this tonite at the onset of the problem comming back. was hoping someone might save me some time and money.
Thanks for your help,
I had similar problems, one time I changed plugs and wires, took care of that
the other time it was a bad 'ignition pack' (?? not sure what you call it but its the thing that sends power to your plugs, I think each one controls 2 cylinders so you misfire on two when one of these 'packs' go down)......But these are just some huesses based on my experience, theres alot of smart folks here who should be able to help you tackle this systematically.