Very shaky idle
Thread Starter
Super Member
Joined: Sep 2019
Posts: 706
Likes: 71
CL55
Very shaky idle
Hello everyone I have a 2002 CL500 with 170k Miles and when I first got it this didnt happen but now at idle when its up to temp it shakes like crazy and when letting off the brake to creep forward you can feel it back and fourth. I replaced all the spark plugs, the coils are good and I have all my vacuum lines connected. Does anyone know what the problem could be? I will attach a video so you can see the rpm it idles at and ill move forward a little you can look at the mirror and you can see the vibration a bit. Thanks!
Video: https://drive.google.com/file/d/14Tg...ew?usp=sharing
I pulled the codes with my OBD 2 scanner (I have no cats)
p0106
p0305
p0307
p0410
p0432
p0422
p0300
The misfire codes could be from before I changed the spark plugs
Video: https://drive.google.com/file/d/14Tg...ew?usp=sharing
I pulled the codes with my OBD 2 scanner (I have no cats)
p0106
p0305
p0307
p0410
p0432
p0422
p0300
The misfire codes could be from before I changed the spark plugs
Last edited by MartinWake; Jan 15, 2020 at 10:48 PM.
Super Member
Joined: Dec 2007
Posts: 980
Likes: 224
2005 S500 Designo
Did you take out both cats or only the rear cats? It sounds like you took out both, so the rear O2 sensor could be a bit pissy and cause the engine to run lean. What are your temps like? What did your spark plugs look like when you pulled them out?
It sounds like your replaced your spark plugs and confirmed the coils are good. Did you clear the codes after doing so? Does the shakiness persist after clearing the codes? How long before the CEL comes back on?
It sounds like your replaced your spark plugs and confirmed the coils are good. Did you clear the codes after doing so? Does the shakiness persist after clearing the codes? How long before the CEL comes back on?
Thread Starter
Super Member
Joined: Sep 2019
Posts: 706
Likes: 71
CL55
Did you take out both cats or only the rear cats? It sounds like you took out both, so the rear O2 sensor could be a bit pissy and cause the engine to run lean. What are your temps like? What did your spark plugs look like when you pulled them out?
It sounds like your replaced your spark plugs and confirmed the coils are good. Did you clear the codes after doing so? Does the shakiness persist after clearing the codes? How long before the CEL comes back on?
It sounds like your replaced your spark plugs and confirmed the coils are good. Did you clear the codes after doing so? Does the shakiness persist after clearing the codes? How long before the CEL comes back on?
Super Member
Joined: Dec 2007
Posts: 980
Likes: 224
2005 S500 Designo
If they looked fine they should be fine.
Did you take out both cats or just the rear cats?
Thread Starter
Super Member
Joined: Sep 2019
Posts: 706
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CL55
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MBWorld Fanatic!
Joined: Jul 2012
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2002 CL500 to CL55 conversion
Did you take out both cats or only the rear cats? It sounds like you took out both, so the rear O2 sensor could be a bit pissy and cause the engine to run lean. What are your temps like? What did your spark plugs look like when you pulled them out?
It sounds like your replaced your spark plugs and confirmed the coils are good. Did you clear the codes after doing so? Does the shakiness persist after clearing the codes? How long before the CEL comes back on?
It sounds like your replaced your spark plugs and confirmed the coils are good. Did you clear the codes after doing so? Does the shakiness persist after clearing the codes? How long before the CEL comes back on?
rear o2 sensors are only there to test if the catalytic converters are working
to answer the original post, a shaky idle is most often caused by a loose vacuum hose.
the m113 engine has a notoriously annoying hidden vacuum hose underneath of the intake manifold which can fail, once it fails it cannot be properly repaired because there is no hose fitting, the hose instead feeds into the intake. They say the proper fix is to replace the manifold
but sometimes also caused by an overly lean or overly rich mixture .
this can be a lazy maf sensor, primary o2 sensors failing, clogged exhaust, bad fuel, clogged injectors, clogged air filters
MBWorld Fanatic!
Joined: Jul 2012
Posts: 1,254
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2002 CL500 to CL55 conversion
There is a technical bulletin from 2001 that states certain ecu’s built in 2001 need to be replaced due to a lean idling condition , you can see if your ecu is on the list by matching up the part number on the ecu
