Rough idle and loss of power suddenly

Tiny
SDMMRT
  • MEMBER
  • 1993 MERCEDES BENZ 560SEL
  • 100 MILES
Car has been running perfectly.
drove to a shop, went in for 5 min. Started car quickly, put into reverse and saw it was not running. Put back into park started it again and Suddenly was running very rough at 500RPM or less had very little power. And would stall at the lights a few times limping it home.
disconnected the battery let sit over night seem a "bit better" and will run but not at all correctly. Very low power, rough idle and rough shifting.
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Wednesday, September 4th, 2013 AT 10:32 AM

15 Replies

Tiny
KHLOW2008
  • EXPERT
Check the spark plugs and related components. Could be a loose plug cable.
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Wednesday, September 4th, 2013 AT 11:31 AM
Tiny
SDMMRT
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Will do and advise.
Happen that suddenly?
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Wednesday, September 4th, 2013 AT 11:51 AM
Tiny
SDMMRT
  • MEMBER
All checked and good right from Rotors back. Makes no difference
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Wednesday, September 4th, 2013 AT 5:17 PM
Tiny
KHLOW2008
  • EXPERT
Did you check the plugs and test if any particular cylinder is misfiring? While engine is running, try to disable each cylinder individually and test if any does not make any difference to engine running condition.

If sparks are not the problem, it could be the injectors.

For checking/retrieving trouble codes, a special tool is required and that would mean going to the dealer.
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Thursday, September 5th, 2013 AT 6:09 AM
Tiny
SDMMRT
  • MEMBER
Yes 2358 are all dead. Which means the left bank distributor is not suppling spark to these plugs.
The main coil wire is suppling power and can be indicated by an inductive timing light. However all 4 plug wires are dead. So the dist and rotor will be replaced. I hope this is it. Because after extensive cleaning and such I can not get a spark from any of these lead wires.
Or maybe the coil is weak?
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Thursday, September 5th, 2013 AT 7:43 PM
Tiny
KHLOW2008
  • EXPERT
It is possible you have a bad coil. Any possibility if swapping with the right bank?
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Friday, September 6th, 2013 AT 6:12 AM
Tiny
SDMMRT
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That is what I thought and am picking up a coil for the left bank.
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Friday, September 6th, 2013 AT 6:23 AM
Tiny
KHLOW2008
  • EXPERT
Keep us updated on how it goes. Good luck.
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Friday, September 6th, 2013 AT 6:51 AM
Tiny
SDMMRT
  • MEMBER
No go coil is fine. Most likely the ignition control module. Problem is how would one test this before you spend Thousands! To get a new one? These are insanely priced!
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Monday, September 9th, 2013 AT 3:39 AM
Tiny
SDMMRT
  • MEMBER
BTW this car is a 1993- 500 SEL with 100,000 miles on it. So it could very well be the module however it would be good to confirm that is the real problem first.
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Monday, September 9th, 2013 AT 3:42 AM
Tiny
KHLOW2008
  • EXPERT
Sorry I could not find any manual testing procedures for the module and if you have access to a scan tool, that should help to determine the cause of the problem.
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Monday, September 9th, 2013 AT 7:11 AM
Tiny
SDMMRT
  • MEMBER
Well I have a new controller on the way.
I do not have any codes showing where I have a check engine indicated. However does one need to clear all codes before the new module goes in?
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Tuesday, September 10th, 2013 AT 11:57 AM
Tiny
KHLOW2008
  • EXPERT
It is surprising that the MIL is indicating with no codes, which usually is a fault with the engine control module. There is no necessity to reset codes prior to installing the new controller and since you have no codes showing, I don't see how you can reset them.
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Wednesday, September 11th, 2013 AT 5:55 AM
Tiny
SDMMRT
  • MEMBER
Kinda what I thought. Just checking your opinion.
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Wednesday, September 11th, 2013 AT 6:19 AM
Tiny
KHLOW2008
  • EXPERT
Lets hope the next thing you does solve the problem. Keeping my fingers crossed.
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Wednesday, September 11th, 2013 AT 6:49 AM

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