engine shut off on drive

Hello,

my problem is 350 slc, automatic, 1975, W107, D Jetronic. I have few questions regarding regulation:

rough idle, I should set idle to 1300 rpm on Parking mode and by switching to drive mode rpm drops to 700 rpm or less, engine works weak;
then I start driving, turning a steering wheel with AC on or off, parking the car engine often shuts off;
rich runing, bad air fuel mixture, how to lean mixture ? I wondered that with fuel pressuere 1,5 bar engine works better on idle, leaner, but still shut off on drive mode.


thank you for your advice
Tomas

Hi Tomas,

thanks for bringing it to forum. Your mixture seems totally wrong. Otherwise engine would have the power to run at 750 rpm. 1300 rpm is for sure too high. Engine can drop 50 to 100 rpm when switching from N to D on automatic gearbox. The reason seems to be fuel excess as you can smell it.

Now what can be the reason? Either it is false air, or broken MAP sensor preferably with misaligned idle-run switch. A mistuned ignition can also create an engine to have no pwer. But then it would not stink with excess fuel.

Now reducing fuel pressure is an absolute NO GO !!! Don't do that. You would correct a wrong mixture in idle and part-load but also ruin mixture at other loads and rpms. You would even risk your engine when it runs far too idle at another load point. It can overheat from lean mixture.

Hello,

I should start from a very begining
some years ago my engine with no. M116.982 , year 75, was in bad condition cylinders compartment - scratches in cylinder, blue smoke.
So I decided to change engine, we swaped with engine M116.985 from a later model, from year 76 and up. We changed just a cylinder block, fuel injection left the same dJetronic.
engine has a good power, compression is even in every cylinder, everything is ok except bad mixture and Drive mode failure.

Question: does such engine blocks interchange is technically compatible and can affect or no affect air fuel mixture and possibility to adjust dJetronic properly ?


Thank you for your answer

Hi Tomas,

block and main shaft should be identical. Changes should be in cylinder head and maybe pistons. Did you verify that your mainfold is air-tight after mounting it. Let us know what vacuum level you have on idle (750 rpm).

Hi Volker,

all manifold rubber parts are changed and new, we tested for leakage , no air leakage. We'll check vacuum level on idle , what is correct vacuum level ?

A good engine should bring -0,5 Bar.