Hello

I have an 84 240GL auto. The car has a bad miss/skip/hesitation. It is the same hot or cold. It spark knocks some also. Sometines it acts like the timing has moved when I try to start it. The tach also swings wildly. The wiring harness is good, I just replaced cap, rotor, and plugs to no real effect. Any clues would be appreciated. I have a couple of parts cars so parts swappinbg to diagnose would be no problem, just need a few ideas as to where to start...


Thanks

Bavman25

Since you've already done some work on the spark side with cap, rotor and plugs, I'd move to the fuel side. Take the fuel supply hose loose at the fuel rail and crank the engine over with the open end of the hose in a jar. Is the fuel flow strong and steady. If so, replace the fuel pressure regualtor since you've got spare parts laying around. If the fuel flow looks weak, check the fuel filter. Does it run better with a full fuel tank indicating the in-tank pump might be shot. Can you hear the in-tank pump running with your ear to the open fill pipe. Is the main pump under the frame running. If nothing pans out here, check the timing. I've found my 83 with a B23F at 297,000 miles runs better with the timing set at 17-18 BTDC instead of 12. One of these days I'll figure out why. jp

If your tach swings eratically while the engine is missing, suspect the ignition harness, its connectors and the hall effect / impulse sensor. On the connectors, there's the well known problem where they don't always make good contact once removed a few times, and benefit from special rolled sleeves (to increase OD) and dielectric grease.

I had a bad connection at the distributir hall effect device and the engine would miss whenever I went over a bump...

Greg

Is it hard to start? What kind of shape is the timing belt in?