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1988 420sel Running Rough

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thebenzmane55

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Registered
05 Z71 Burban 2JZW210TT 93 500E and 20 others
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105 Posts
Discussion Starter • #1 •
Ok, I am a Mercedes Benz Mechanic and my 420sel is only my winter car, But the problem i have is it idles rough and I can not figure out what is going on. I have put on distributor cap, rotor, wires, plugs, different ignition control unit, coil, almost everything for the ignition system, I have also run 93 octane with bottle upon bottle of injector cleaner, tapped on the injectors and everything. But still the car idles rough at idle. Do i have to tare the motor down and have the valves reseated? Has anyone else had this problem and was able to fix it with out engine work?
 
L

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Mercedes 420 SEL 87'
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165 Posts
#3 •
My 420 gives a kick every 30 seconds or so at idle and the oil pressure gauge bounces at the same time. Changed an extensive list of parts but still hasnt gone away.
 
AxelWulff

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Premium Member
1990 SEC
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4,148 Posts
#4 •
In addition to worn ignition components, you'd want to check the follwing:

- Vacuum leaks (very commmon issue...)
- EHA (electro-hydraulic actuator)
- Cold start valve
- OVP (over-voltage protection)
 
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AxelWulff
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