'87 560 SL RPM drop/surge @ 50 mph

[cjingersoll]

At @ 50 MPH, the engine RPM drops 200-300 RPM then surges back up, and cycles like this when I'm cruising, not accelerating. I've replaced a lot of parts: fuel distributor, O2 sensor, intake manifold gasket, EGR valve, EHA unit, throttle valve assembly.
Thanks for any help!
cjingersoll

[yabass]

Hello, i also have an 87 sel and noticed that you had the fuel distrubitor replaced. I have been told that that is a problem with mine and wondered if you did the work yourself or had done, and how big a pain is it to do? also if you replaced the distrubitor with a rebuilt one ?, what is the reason for the vast price range in the parts ?? they seem to go from 500 to 2300 ? i know you get what you payfor but that goes a long way. Hope you had a Merry Christmas and will have a Happy New Year... Thank You , yabass

[johnjzjz]

i did not see you have changed the gas filter but i guess you have done that as its cheap -- jz

[yabass]

no i didn't, i just relied on a mechanic actually two that both said the samething. it is a second car and it has been sitting for me to get to it. I did have the gas fulter replaced about a year prior to the problem but they can go anytime i am sure. I can do it, the one in the rear under the frame by the wheel well?? Thanks for you email

[yabass]

is a 1987 able to be diagnosed by a code ?

[Roncallo]

Originally Posted by cjingersoll

At @ 50 MPH, the engine RPM drops 200-300 RPM then surges back up, and cycles like this when I'm cruising, not accelerating. I've replaced a lot of parts: fuel distributor, O2 sensor, intake manifold gasket, EGR valve, EHA unit, throttle valve assembly.
Thanks for any help!
cjingersoll

Try removing the cruise control link and see if this still happens. That will rule out cruise control issues. This may also be an idle valve or idle control unit.

[Roncallo]

Originally Posted by yabass

Hello, i also have an 87 sel and noticed that you had the fuel distrubitor replaced. I have been told that that is a problem with mine and wondered if you did the work yourself or had done, and how big a pain is it to do? also if you replaced the distrubitor with a rebuilt one ?, what is the reason for the vast price range in the parts ?? they seem to go from 500 to 2300 ? i know you get what you payfor but that goes a long way. Hope you had a Merry Christmas and will have a Happy New Year... Thank You , yabass

I have a good used one for sale on my E-bay sight.

[cjingersoll]

I had an after market shop specializing in German cars remove and replace the fuel distributor. They charged the upper price range for a rebuilt one. I had to replace it and the injectors because of rust from water in the fuel and the car having sat for a long time before I bought it from an older man.

[whunter]

I moved this to the SL forum for a more focused answer.

RE: Your PM, 1987 560 SL RPM drop/surge

---------------------------------------------

Issue: RPM Drop/Surge while cruising 45-55 mph
Hi Mr. Hunter; I'm new to this forum and have posted the below matter; I am sixty-two, aging fast, frustrated and now quite poor from fruitless attempts to fix a problem, spelled out below.

Repairs, to date, to no avail:
· 6/11/08 Replace Fuel Distributor EHA
· 10/7/08 Replaced O2 Sensor/Sensor kit, intake manifold seal rings,
· 2 air distribution hose and connectors, intake manifold gaskets, intake plenum gaskets, Vacuum hose plug, fuel distributor o-ring, fuel injector seal, washer nozzle duel jet and connectors, ERG Valve, throttle valve assembly and base gasket.
· 11/11/08: Replaced fuel distributor, o-ring, fuel filter, fuel injectors and seals
· 1/19/08 : Replaced Air Mass Meter NLA 5/08 (potentiometer), throttle body gasket, air duct housing, Air. Dist. Hose connector, air duct flange, new spark plugs.

I'd appreciate any help.
Thanks, Charlie in, PA

[yabass]

Thanks for all the help everyone, I replaced the fuel distrubitor with a used one for $175.00 and it runs like a champ. As a matter of fact i just got it smoged and paste yesterday!! thank all of you once again
yabass