labguy

Cars been running fine until started it up at lunch. It immediately began running rough and had no power. Engine light came on. When I finally got it up to about 25 mph, it began to even out and run smoother. All the way to my Indy, it would begin running rough and wanting to stall at idle. He won't be able to look at it until Tuesday.

I am no mechanic. Any thoughts?

nkx1

Sorry, no idea!

My mechanic would tell you (over the phone) that it could be any one of 200 things (or however many possible engine codes there are).

Good luck- hopefully it's nothing too catastrophic!

It would be cool if you can provide an update in case anyone else has a similar issue down the line.

Rudeney

So it's only an issue at lower speeds? Just an off the cuff guess, but maybe it's a bad accelerator pedal. You might try the resync procedure:

1. Make sure everything in the car is turned off and closed.
2. Turn the key to position 2 so all the dash lights are illuminated.
3. Press the accelerator fully to the floor, depressing the "kick-down" button.
4. Hold he pedal for 5 seconds and continue to hold it down.
5. Turn the ignition switch back one click to position 1.
6. Release the accelerator pedal, but leave the key in position 1.
7. Sit quietly and wait for about two minutes - do NOT open or turn anything on.
8. Listen for a "click" or "ping" noise form the dash.
9. Start the engine and drive the car for at least five minutes.

Merc Mania

My 2009 CLK 550 began idling noticeably rough a couple of days ago when I started the car in the morning, so I hurriedly turned off the ignition and had it looked over. Turned out that the starter motor was beginning to fail due to some internal corrosion, and was not fully retracting after the engine cranked over, causing the starter cog wheel to remain partially engaged with the engine flywheel, as the engine idled.

Luckily I cut it off quick before any damage was inflicted on the flywheel, so once the starter was refurbished, the engine fired up on the first crank, and proceeded to purr like a kitten, smooth as silk. This is got to be one of the most unusual causes of a rough idle that I have ever encountered in any vehicle.

labguy

Mechanic contacted me today and said he pulled the code and it was for "Cylinder #1 misfire". So, they pulled the plug and he said it looked fine and asked me when plugs were last changed. I told him at 106k (at 128K now) miles and Dec 2017. So, plugs should still be good. He also said that when they put the plug back in, it no longer was misfiring and that it drove beautifully. They are going to drive it again tomorrow.

Any more ideas with the added information?

Rudeney

Bad coil/plug wire? Or maybe it was just poorly seated?

labguy

I am hoping it was just poorly seated and when they took it out to inspect it, they put it back correctly. Anyhow, picking it up today.

BTW, they did a ATF change and drained the TC without me even having to ask!