Hi, I'm new to the forums and I'm already asking for help, heh. I got a 88' 420SEL thats in pretty good shape body wise, the thing that bothers me is the engine performance and the gas consumption. The car idles really bad, not every time but most of the time. You can practically make "Shake-&-Bake" meals just by sitting in the car. Also, there is the lack of power from the v8, feels like its not running all cylinders. I don't know about anyone else's 420's but the car can barely reach 80mph without the engine struggling... so I go 60mph on the freeway.. [:@] .. This car is sucking the living crap out of my wallet. I would fill it up completely with premium on monday, then by friday it would almost be time to fill up again...
I'm guessing it could be injector problems, if not carb... I think its fuel injected [&:] . I'm deciding whether I should change all of the injectors to try and improve the idle and the gas consumption, since I'm thinking its running way toooo rich.
If anyone knows what the problem is, please let me know before I go ahead and perform these changes. I like to be at least 90% sure of what I should do before I actually do them. Please help! I really love this car, but I will have to sell it if the constant fill ups continue...

 

Thats because it probably isnt running on all cylinders. Replace the spark plugs and the wires and if that doesnt improve it then replace the cap. But wait for the cap untill after the plugs and wire. As far as fuel consumption. Yeah they like gas i have a 560 and get between 14 and 16mpg so it thats ur average with new plugs i would think with the smaller motor 18 might be right.

 

Thanks, Ill try that. If your advice doesnt work then Ill let you know. But again, thanks