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1994 E420
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3 Posts
Discussion Starter #1
rough idle. If sits for 2-3 days will start up right away, run fine for a while, then will not restart until wait 20-30 minutes. Lately has been running very poorly. No power. missing badly. Recently changed wiring harness and ignition wires both of which were bad. This helped a bit. Anybody know how to check the injectors. Or have access to engine diagnostic manual. Any ideas. Thanks.
 

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W126C AMG 6.0
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846 Posts
Did you check the distributors and coil packs? They have been known to get brittle and crack so your spark is spread out. Injector problems are rare.
 

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500E, E320, 190E, E55
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1,006 Posts
I would change all of your ignition components including spark plugs and both ditributor caps and rotors. M119 is very sensitive to worn caps & rotors.
These motors do not have coil packs. When was the last time you replaced your fuel filter? Keep us posted.
 

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Depends on the day!
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13,337 Posts
Could be a throttle slide that has given up the ghost..but I would check the caps/rotors first...much cheaper. Pull your plugs, if the car is running THat lean you'll see it in the plugs.

Jonathan
 

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1994 E420
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3 Posts
Discussion Starter #6
I checked the plugs previously and they were OK. I hesitated to buy new caps and rotors since they looked OK and I already spent $1100 on the ignition wires and harness. I can pull the plugs and check them again. I can buy the caps and rotors too since its only a couple hundred bucks but I actually suspect it is in the emission control system (the engine check light did come on briefly once). The engine runs so hot which is what destroyed the wiring harness so I thought maybe the injector seals were also destroyed but I have not pulled the injectors. I will pull the plugs again and check the vacuum this weekend. Thanks for the advice and I will keep posted.
 

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1994 E420
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3 Posts
Discussion Starter #7
Thanks to all for suggestions. Turned out it was the rotors/caps. Changed them both and now works fine. Am very surprised as these are usually high tolerance items which wont fail on most cars unless they are obviously cracked/arced. Anyway hopefully fixed now.
 
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