Problems with late US 280 SL Pagoda- help needed

[Durango2k]

Hi there,

I am facing a lot () of troubles with my late 280 SL.

It was exported to the US in 1970, and it features some emission control stuff.

Problem: When cold all is fine. When hot it idles ROUGH and cuts out. Almost undriveable in town.

I found:

- the Head is stamped 280 SE
- the camshaft is a "05" one
- the pump is a R24Y one
- I have 2 rectangular relay blocks on the front left fender and a small "tin can" with 2 hoses + a wire going under / in it
- the dissi is a 062 one, so it has a transistor ign.


This means to me I have a late emission controlled US car. 160 HP, not the 170 HP Euro model.

Now, I looked and took care for:

- valve play: Adjusted. Since, it revs better
- connected the "tin can" to the pipe which formerly went directly into the distributor
- checked timing: looked fine to me
- checked and adjusted (new ball joints) the gas pedal actuator parts. Now the throttle opens when the pump "opens".
- I turned the "fob" on the pump leftmost. Maybe I can give it a few more turns but not many I believe.
- I checked the WRD: Closed the huge air correction screw, caused a loud hissing noise when cold. Pressing the intake pipe on the rear made the engine starve. When warm this was not the case- so it is not sucking air and this means the WRD is ok.
- adjusted the throttle to the point where it is JUST starting to bind.

Effects: Since I have done that, it is at least driveable when hot above 2500, 3000. Formerly, it went like a cangaroo from ~2300 upwards. Exception: Accelerating it ran nice, but driving along was impossible. This tells me it might be a problem with "not enough fuel OR a problem covered by a richer mixture".

But the main problem of a rough ride + a VERY rough ride at idle did not go away after having done the above.

What can I do next ? I think I will give it one more try and disconnect the pump from the throttle after driving it hot and check if it idles better with more fuel, or more air, then.

I then thought I should check ALL sensors (maybe one is giving wrong input, now, how do I do that- I don't even KNOW them all ?), and / or remove the ignition controller, and check that (no idea how, maybe I can open + resolder it or something like that) ?

I have at the moment not the slightest clue what fault I am hunting here. Wrong mixture ? Ignition troubles ?

Many thanks for any help- a structured way to follow to eliminate as much as possible would help me most....

Carsten

P.S:- Just found this maybe the wrong section- is there a method to moove this post to "where it belongs" ?

[Cees Klumper]

Hello Karsten and welcome.

I don't really know about the emission controls (others here will be able to comment on those) but noticed the following in your post:

"I turned the "fob" on the pump leftmost. Maybe I can give it a few more turns but not many I believe."

If you are referring to the slotted idle mixture screw located at the rear of the injection pump, you appear to have turned it to the richest possible idle mixture setting which may not be what the car needs.

"I checked the WRD: Closed the huge air correction screw, caused a loud hissing noise when cold. Pressing the intake pipe on the rear made the engine starve. When warm this was not the case- so it is not sucking air and this means the WRD is ok."

I am not sure I understand because as far as I know, there is no air correction screw on the Warm Running Device, only a small air filter. The only air correction screw I do know is situated on the air intake manifold. This should be used to, together with the idle mixture screw, set the correct idle air/fuel mixture.

Have you checked / replaced the plugs, plug wires, coil other ignition components ? Are you sure you have the correct distributor (advance/retard type) suited to the other components? (my car gave me similar troubles when I first got it, and it turned out to be the incorrect distributor type). You could consider replacing the ignition system with the more modern 123 unit, this would not only eliminate that possible cause but could improve the engine operation more broadly.

Another area of course is the whole fuel system; debris from sitting has caused many huge headaches. See the many posts here on the subject.

Sorry I can't be of more help, but these are the things I would look into first if I were you.