1993 300E 2.8 Cold Throttle Response

[jbjork70]

Hello,

I have a 1993 300E with a 2.8L gas auto and 180k miles. My main issue with the car is throttle response when the engine is cold. Until the engine is fully warmed up, when driving the engine slowly accelerates without regard to how far down I push the accelerator. Once the engine is hot, throttle response is fine.

A couple strange issues are when the engine is cold, the throttle response is poor until I hit 2800 RPM. Once the engine hits 2800 RPM, the engine finally "takes off" and accelerates dramatically. I'm thinking the issue may be a vacuum leak issue but I have yet to find any visible leaks or cracked hoses.

Also, I have some hard starting in cold weather. If the engine does not start on the first crank without any throttle, then I have pump the throttle to get the engine to start. I don't think I should have to use throttle when starting a fuel injected vehicle.

I have a code reader with the blinking light from Ebay (works great), but after I reset the faults and fixed some issues, I'm showing no current faults for several weeks. I have also replaced the spark plugs, plug wires, air filter, water temp sensor, and air intake temp sensor.

I've done a lot of research on these boards and in books but before I pay to have a tech to go hunting for the problem, I would appreciate any possible suggestions you might have.

Thanks,

John B