My Mercedes-Benz 1979 280 CE idols fine. When not in gear or asking for power or driving. The car seems to stall when accelerated. I am unable to figure out why. It has a mechanical K jet. Any suggestions.
Alright, update on the issue
The issue is still there however, when it starts cold it does work fine till it gets to operating temperature. I do feel a it of hesitation but it does accelerate. After about a 5 minutes and a mile long city drive the same error happens. If I accelerate there is no response. and it makes a pop if I force the pedal down. So I pulled in to the gas station and filled it up with gas. After that it did start when I floored the accelerator and then it drove back normally with the accelerator responding. I am not sure where to do from here.
I have checked the fuel pressure, it remains the same
I have replaced the warm up regulator with two units and still the car does the thing mentioned above.
*Car does not have a o2 sensor with Lambda drive, its mechanical K-jet
Any suggestions......
I have not owned a car with that system in ages. (The old 8-valve 2.0 Saabs used it.) Maybe some hints here:
https://www.benzworld.org/threads/k-jetronic-troubleshooting-from-a-couple-of-specialists.1667628/
Does your fuel injection system include the Lambda feedback system with O2 sensor? The K-Jetronic is very sensitive to any vacuum leaks (you said you have an intake manifold gasket leak) and to fuel distributor adjustment, and with Lambda the O2 sensor needs to be good and the duty cycle needs to be correct for it to work properly. Ditto for fuel pressure. This is decades-old fuel injection technology and it cannot adapt and correct for problems the way that today's sophisticated systems can. Everything has to be just right for K-Jetronic to function properly and there are not a lot of mechanics around any more that are familiar with it.
https://www.benzworld.org/threads/k-jetronic-with-lambda-overview-and-adjustment.2182425/
No sure, Have to check if its Lambda system. But its not electronic. Its a mechanical K-Jetronic.
I'm familiar with it having owned cars with that system. Although K-Jetronic is mechanical, the Lambda addition (introduced by Volvo in 1976 and quickly adopted by others) adds electronic feedback control to the system for emission control. I don't know when K-Jetronic Lambda was adopted by Mercedes, but the link I provided shows adjustment procedure for a 1980 model so equipped.
It probably doesn't have any compression left.
Why the down vote? A 43 year old engine, low compression is certainly a possibility for lack of power.
Checked it and it has compression in at cylinders. All we averaging the same. after wet and dry test
What was the compression reading? What number PSI?
Average were around 118 psi for all 6 cylinders. when tried dry and 121 when wet.
Catalytic converter may be clogged.
Its free flowing.
How do your spark plugs look? Any vacuum leaks? Fuel injectors OK?
https://ngksparkplugs.com/en/resources/read-spark-plug
Yes they are checked and the injectors are new, plug, wires, coil, rotor and cap are new. It does have intake manifold gasket leak but it does not make a sensible reason that the engine stalls under load.
Compression should be 150 psi+ for all cylinders.
Yeah, it's a bit low but there's still enough compression that the engine should run OK albeit with a little less power than new. I've owned and worked on those K-Jetronic systems and they can be very touchy. The intake manifold gasket leak is a big red flag, that fuel injection is very sensitive to vacuum leaks and if it has the Lambda feedback system a leak will also throw the duty cycle out of whack, creating problems. I think it's going to come down to either the fuel injection not working correctly or maybe the ignition cutting out. (If the latter the spark plugs should show signs of carbon fouling or even wet gas.)
Check the ignition coils, distributor and wires I've worked on a few of these that had some what similar issues and it was a misfire only under load and or any increase in rmp.
Is it an automatic? Does the tranny shift as it should? Any better when shifting it manually?
