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1987 Mercedes Benz 300E
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38 Posts
Discussion Starter #1
need some help on my W124
i already changed the plug wires and put in new plugs, for some reason, when in idle, the engine seems to sputter and is not as smooth as it was or suppose to be.

what else needs to be replaced when changing plugs and wires??

thanks for your help in advance!!:(
 

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99 CLK 320
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85 Posts
need some help on my W124
i already changed the plug wires and put in new plugs, for some reason, when in idle, the engine seems to sputter and is not as smooth as it was or suppose to be.

what else needs to be replaced when changing plugs and wires??

thanks for your help in advance!!:(
Get yourself a homebrew code reader and pull the codes.

Just search "code reader"
 

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Registered
MB w123 250D om602 10v 1983
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95 Posts
need some help on my W124
i already changed the plug wires and put in new plugs, for some reason, when in idle, the engine seems to sputter and is not as smooth as it was or suppose to be.

what else needs to be replaced when changing plugs and wires??

thanks for your help in advance!!:(
I have the same issue on my 200E, I've changed plugs, wires, cap, rotor, etc etc and still won't run smooth, the only thing I've found out that gets the car to run without "misfire" (it's not really a misfire but running unclean) is to adjust the duty cycle to about ~70-75% which is not optimal, I'm still trying to figure out why.
 

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1,749 Posts
need some help on my W124
i already changed the plug wires and put in new plugs, for some reason, when in idle, the engine seems to sputter and is not as smooth as it was or suppose to be.

what else needs to be replaced when changing plugs and wires??

thanks for your help in advance!!:(
Was this present before you installed new plugs/wires? If so, is it the same/worse/better?

Does it misfire all the time, or does it seem random, doing it some days but not others? Is the misfire constant, or do you feel it only occasionally, if relatively frequently?

Does it happen for an entire trip, other times it misfires a few times at a stoplight, then is fine? Length of run-time, temperature (both engine and ambient), and driving environment do not seem to have any effect on mine, which bugs the crap outta me.

I have the random kind, and I think/I] it's a crankshaft position sensor, but I've not yet tested it.
 

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89 300E; 00 E320
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2,515 Posts
For basic tune up? If they are old or worn then distributor cap, rotor, rubber gasket.

A little more: Coil, OVP, oil filter, oil change, air filter. Clean throttle valve, check for cracked hoses and vacuum leaks. Clean throttle body, clean and ATF throttle linkage. Replace all fuses with copper fuses.

A lot more: Oxygen sensor, fuel filter, fuelpump/s, relays, sensors...

What did the plugs look like that you replaced, what plugs did you use, how much do you want to spend just replacing parts? Diagnose - Repair
 

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1987 Mercedes Benz 300E
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38 Posts
Discussion Starter #6
thanks for all your comments
well initially the car was running smooth then all of a sudden it started misfiring, i looked at the cables and there was cracks so i decided to replace all the plug wires and the spark plugs as well but never replaced the rotor, distributor etc needed for the tune-up. should i go ahead and replace those too??
 

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1,749 Posts
thanks for all your comments
well initially the car was running smooth then all of a sudden it started misfiring, i looked at the cables and there was cracks so i decided to replace all the plug wires and the spark plugs as well but never replaced the rotor, distributor etc needed for the tune-up. should i go ahead and replace those too??
Absolutely!

The rotor and distributor can be large contributors to misfiring.

If you're gonna do it, go all the way.
 

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1,749 Posts
kool, thanks mckellyb, ill look into it next week
I know it sounds like I'm making it up, but after a certain, unknown point of time, as soon as you so much as disturb the dust on some items, they stop working properly.

For me, electrics are one of those things.

As a long-time connoisseur of beater cars, you'd be shocked what can work seemingly just fine...until you touch something even semi-related.
 

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300 CE 24V Sportline
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918 Posts
Only the best will do ...

kool, thanks mckellyb, ill look into it next week
Don't be tempted to buy low cost distributor parts. I've done this and regretted it.

My advice is to go to MB and ask for a discount. I did this and the price came out the same Bosch or Beru from independent suppliers.

Failing that, Bosch or Beru.

RayH
 

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W123 wagon, E30 325iS, Suzuki SV650S
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83 Posts
I recently had a problem with my E30 BMW misfiring which then escalated to running very roughly and loss of power. Turned out that one of the fuel injector wires wasn't fully seated and the plug was fouled. Reconnect the wire, new plug, and viola. Back to tip top shape. There's the possibility it could be a vacuum leak somewhere too. I've seen similar issues with these older Benz's that were a vacuum leak.
 

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1,749 Posts
Don't be tempted to buy low cost distributor parts. I've done this and regretted it.

My advice is to go to MB and ask for a discount. I did this and the price came out the same Bosch or Beru from independent suppliers.

Failing that, Bosch or Beru.

RayH
I've found, for the older models, sometimes the dealer offers a discount just 'cause you're keeping one on the road!

The Austin, TX, place was like this. Was quite cool.
 

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W123 wagon, E30 325iS, Suzuki SV650S
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83 Posts
I've found, for the older models, sometimes the dealer offers a discount just 'cause you're keeping one on the road!

The Austin, TX, place was like this. Was quite cool.
Sometimes the service techs even come out and gawk at the classic MB. My friend recently took their W123 into a dealership for a service and the service techs didn't know how to work on it. They didn't how how to gap points. They were all in awe that a '79 was even still on the road.
 

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W123 wagon, E30 325iS, Suzuki SV650S
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83 Posts
cbc atl

You're very welcome. It's a pleasure to be here and sponsor the site. And these older Mercedes have a soft spot with me. My family drove them as I was growing up and I've worked on many of them. Lots of memories.
 
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