I started this topic in an old thread but am moving it here since it's become apparent that this is a separate issue for a separate subforum.
Synopsis of the issue with my 1985 Eldorado as it was:
- Hunting/Surging at idle (Drive + brake) after things warmed up (usually a ~10 mile freeway drive).
- Stalling sometimes at stoplights or when doing parking that required reverse (again after warming up).
- Smooth idle in Park (I started putting the car in Park at stoplights to avoid stalling).
Thank you for the advice, I now agree that it's probably not caused by the torque converter. I do have the factory service manual but my copy is missing the ISC adjustment pages! I read the procedure on the forums but have been a little afraid to do it (the instructions were a bit rough and I thought I read something about risking frying the ECM) and at this point I'm also not convinced it's the culprit. I had though perhaps the EGR was to blame but after removing it and checking for deposits/blockage I found the passage was very clean and the plate seemed to function as it should (I just wanted to cross that off of the list).Originally Posted by carnut
Driving around town has been perfectly fine aside from some slight issues at idle, but last night I foolishly took it on a 200 mile trek (leaving the manual behind so I don't have it with me to reference). Well on the way there's one long hill with a steep incline that also requires me getting in the very right lane and because the car maxes out around 40mph with the pedal to the floor. This particular time, I noticed it was running pretty rough when I got to the top but there wasn't much I could do... It smoothed out and after driving around 50 miles further I hit traffic. That's when I noticed the rough idling but this time different. Rather than hunting and surging, it was just very rough, perhaps with a slight rhythm. To make matters worse the dash Brake light came and went as I navigated the traffic. The brake pedal was hard when the light was on and I'm under the impression I was manually applying all the force. At times I would apply the brakes manually and apply a bit of gas just to juice the booster into helping me out.
Now my thoughts go to vacuum... I did a rough visual inspection of the lines and there's no painfully obvious rot/holes. I have some WD-40 handy to inspect the lines with but I haven't gone ahead and done so yet. I'm thinking either the booster itself or the lines aren't sealed? The ISC seems to be doing its job, I can see the plunger moving in and out to compensate for power requirements. The engine still fires up perfectly fine, seems to idle smooth for a few minutes but now the rough idle also occurs in Park as well (Park was untouched before).