1978 280SE Engine Sputtering

[wbeyers]

It used to happen rarely, but now more often. I will be driving along and I can feel the engine beginning to sputter. (six cylinder gas) If I press the gas pedal, it will get worse. It seems to occur after I have been driving for a while or when it is hotter outside. It used to be fine in the morning when the weather and engine were cooler, however, now it occurs more often.

I have replaced the fuel filter, spark plugs, and spark plug wires to no avail. I drive this car every day and love to do it. You other owners know what I mean. So it is so frustrating not to be able to depend on it. This is my first post and it is great to be in communication with like minded W116 owners.

Thanks, Bill

[vlv8vic]

Welcome, and they certainly are a great car.  Mine has a particular tune to it that my other half has come to know which alerts her that I'll be coming in teh door in a few minutes!

In terms of your issue, I'm still probably a noob by the standards here but i don't doubt you'll get the answers you need.
A few things I wonder-
Does the car start alright?
Fuel pump perhaps?
Everything seems to revolve around the bloody warm up regular at the moment, it's all i can think about.
Maybe the coil is on the way out, they'll regularly cause issues when warm if they're packing it in.

Hopefully someone can give you more idea of what to test and check to get to the bottom of the issue quicker than i could.

Japes.

[plmstr92]

Maybe now is a good time to check valve clearances.From experience with the M110 unit the required clearance tends to close up over time and causes poor running.Its a progressive action so it would worsen over time.

Good luck with your diagnosing 

[oscar]

edit; deleted my post.  Just realised your car has k-jet which I know nothing about so over to someone else    Welcome Bill

[sblakely]

My '79 280se sputtered only when idling or coasting.  I fiddled with the ignition timing and the sputtering stopped.  Apparently it was firing early.  You probably already have the ignition timed in, but if not it's an easy thing to do.  There's a page for adjusting the timing in the library.

[wbeyers]

It always started roughly, however, when warmed up, ran very nicely, particularly after new plugs and spark plug wires. Of course, later when begining to sputter, it was like night and day. As I mentioned, I have also changed the fuel filter. The fuel pump is an interesting question. Is that located in the fuel tank and also is there more than one fuel filter?

Thanks for your advice so far. I passed them on to my mechanic who was intially receptive, but I think is perhaps insulted. Nevertheless, he charged me so far with two repairs that didn't fix the problem, so I am not being sensitive about his feelings at this point.

Cheers, Bill

[plmstr92]

Fuel pump is external, under the car at the rear.A couple of checks you can do is test for correct fuel pressure and flow, which would be 1ltr per 30 seconds if i remember.