T-Roll

I recently bought a clean, stock 2001 E55 AMG with 125,700 miles on it...it shakes a bit / has a miss when idling and my mechanic said he didn't know what was causing it...that it'd likely be hard to determine, however, he recommended I buy a bottle of "B-12 Chemtool Injector Cleaner" by Berryman (see below).

Two questions for all you guys please:

1) Any guesses why it may shake a little / miss when idling?

2) Have any of you had success with the below product? (or know much about it?)

Thank you
T-Roll

B-12 CHEMTOOL® INJECTOR CLEANER FUEL TREATMENT
Formulated with High Energy Solvent Technology (H.E.S.T.) to clean all gasoline injector system circuits by dissolving varnish, carbon, and gum deposits. Contains highly effective detergents to thoroughly clean and lubricate injectors. Eliminates after-run.
Part #1112 NET 11 fl. oz. Pour Bottle

saintz

Have spark plugs been changed? They should have changed at 100k miles.

Mercedes recommends Techron. A lot of people have used Sea Foam. These are generally all pretty similar cleaners. If the problem is a clogged injector causing the stumble on that cylinder, it could help.

jtbeche

Wouldn't these also be the same symptoms of a bad MAF?

saintz

Good point. Does it idle rough, or does it actually have a misfire? Misfire should throw a code you can grab with an OBDII scanner. Also, a misfire would be more rhythmic, once every 8 fires, versus just being "randomly" rough.

Also check for leaking or sagging engine mounts. They go bad easily and will cause vibration through the chassis. When you rev the engine with the hood open, you would also see the engine tilt a lot.

desired_speeds

usually the miss/ shake is caused by the spark plugs/ wires. In my case, it wasn't. I'm still trying to trace the reason behind it. I get no power loss whatsoever, just that when you're sitting at idle the car wobbles a bit sometimes.

jtbeche

I have the same issue from time to time now. Not always, but on occasion when I'm sitting at a stop light. I have almost 130K miles on the car and the previous owner changed the plugs/wires at 100K so I'd assume those are alright. I was thinking it might be time to change my MAF. I just ordered motor mounts yesterday as it's also pretty rough when I idle. I'll start with the mounts and maybe change out the MAF if I continue to get the wobble and hope that fixes it.

ruBENZ

+1

desired_speeds

Thats the thing though, my mounts are new and I swapped the maf with another bosch and it did the same thing. When hooked up to star, the actual values for smooth engine running show that cylinders 4, 5, 7, 8 fire out of range every once in a while. I've swapped coil packs and wires and it's still the same cylinders, so I'm pretty lost at this point. Someone told me to clean the egr because if it gets stuck slightly open, it would not throw check engine but may cause these symptoms with no power loss.

MBFLO

Thats only time it ever happens to me . Not on occasion but once in a while . I'll pull up to the stop light and itll start to jerk like it wants to go but i notice the rpms go up n down slightly . usually put in in N and give it some gas and put it back in park n goes back to normal . My guess is its he MAF but i just keep tellin my self its that 5.5L engine wantin to let loose