W124 hard to start, rough idle/acceleration - PeachParts Mercedes-Benz Forum

Matt565 · #1 06-01-2002, 10:56 AM

Lately, my 260E has been very hard to start when it is hot. If it is cold, it fires right up, but if it has been running and i try to start it, it is almost impossible. It tries to start (vibrates for a second) then cuts off. It will do this several times before starting. This is quite embarassing in a crowded parking lot.
Also, the acceleration is not smooth. It feels like the engine is pushing and pulling, especially at higher RPM's and it does it worse when the air conditioner is on.

Matt

jay123 · #2 06-01-2002, 12:45 PM

Check your OVP fuse..10 amp on the OVP relay. Also, consider replacing the fuel filter, cap, rotor, and plugs. Could also be the cold start valve. Usually, when the OVP is bad, or the fuse blown (10amp), the cold start won't work.
Give it a try..

Matt565 · #3 06-01-2002, 03:00 PM

The cold start valve is fine, because the car starts good when it is cold and ildes at higer RPM's until it warms up. I checked the OVP fuse and it is perfect. I am not sure how to diagnose a bad OVP, but the ABS and airbag lights are not on and when I took out the OVP fuse to check it, the ABS liht turned on. this makes me think that the OVP is ok. Also, I have replaced the rotors and plugs within the last 200 miles. Sorry to sound ignorant, but what do you mean by "cap"?

Matt

jay123 · #4 06-01-2002, 05:14 PM

The distributor cap. If hard start is when hot/warm, i agree it won't be the cold start. Sorry about that. I miss read and focused on the hard start issue. Consider changing out the fuel pump relay and fuel filter. Could be the culprit. Check some of the other threads here for the similar issue. Do a search for hard starting..

Gary! · #5 06-01-2002, 06:49 PM

How the engine run when driving? any irrgular and rough running? if yes, try the compression test on all the cylinder, see whether is the lack of compression or not.

#6 06-02-2002, 11:53 AM

I had the same problem with my '94 E320. Turned out to be the fuel pressure regulator. Had the OVP problem about 2 years ago. Symptoms were car not starting at all and then after waiting a while fired right up. Very unpredictable.