500SEL no power at all!
 

Hey guys, bought a 1985 500SEL us version about a year ago. Car sat for about 10yrs. New fuel filter, pump, sparkplugs and drained old gas and got the car running. However when i drive the car it has no power, if i stomp on it the car accelerates about like a old ford pickup. I have faster take off in my 350SDL! Not sure what all i should check. Since its us version i plan on removing both cats which will should help. Im curious as how to bypass the 02 sensor? My assumption is a resistor or very simple circuit would do it. I also understand that these cars have a timing retard resistor for us version. Not sure where it is but since i run 93octane I think removing that would help. And someone suggested a fuel distributor rebuild to me. Anyone have any good suggestions? Im selling the car to a friend and he needs it within the next week or so, so id like to get this problem resolved asap.

I would check the fuel pumps. Also the fuel distributor is probably all gummed up. Does it sputter like it wants to accelerate or does it feel like it is running like it should if it only had like 50 horsepower? When the fuel pumps were failing on my 420sel it would sputter real bad because I was starving for fuel.

no sputter at all just feels like it needs +50hp. and the fuel pump and filter are brand new.

Quite possible a gummed fuel system including the injectors .Techron or something similar may do the job.
Is Fuel pressure normal?
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I put something similar to techron in when i first got the car. it was supposed to take any water out of the fuel and clean injectors. I have no tested the pressure. I had assumed if the pressure was bad the car wouldnt start.

Make sure both fuel pumps are running. I solved this problem once by replacing both fuel pumps, one of them did not work.

the car only has one fuel pump, and i put a new one in and its working.

You have the older model after 1985 they have two pumps. What size pump did you use 4 or 6 psi?

In all honesty...no idea, when i bought the new one i just matched it with the bosch part# it called for. So it should be the right one

What kind of spark plugs did you use? These engines run best on a basic plug like the NGK BP5ES, also the condition of the wires/rotor/cap all matter too.

Bought OEM plugs from Benz, and the wires and rotors werent replaced but they look in very good condition

Low power can be caused by an improperly adjusted fuel distributor, or a malfunctioning EHA (electronic hydraulic actuator) on the side of the distributor....

Make sure the transmission control pressure cable is hooked up and adjusted correctly. If it's shifting late / not downshifting correctly it can make the car feel like a dog. Also, make sure no brakes (esp. parking brake shoes) are dragging - if it sat for a long time that could be a possibility.

A choked exhaust system will give you very similar symptom ,and quite possible over a long period of disuse . Easy check with a vacuum gauge, or loosen joints progressively to get a free revving engine in Park .
I assume it does not rev up readily in park.
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It revs just fine in park as far as I can tell, no delay or skip or anything. I suppose the transmission cable could be a possibility as afore mentioned. It does seem to shift rough buti don't think that would be the cause of such a large power loss like what I'm getting