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Old 11-28-2007, 02:48 PM
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Join Date: Nov 2007
Location: texas
Posts: 7
560 stil acting funny

I've posted before about some idle/power issues with my '86 560sel. It starts right up when cold, but idles roughly for a bit. When I take off, I have alot of power, but when the car warms up, the power seems to be so so. As I've stated in previous posts, I've replaced the OVP, EHA, fuel pump relay, fuel distributor and temperature switch, cleaned the idle air valve, checked timing, and changed all manifold and vacuum lines, as well as all filters. I have sprayed carb cleaner on and around the injectors, but have not noticed any change in idle, that would indicate a leak. The only other thing that has not been changed out as of yet is the o2 sensor.

The car has a hesitation/sputtering when it warms up. It manifests itself when you accelerate from a stop. Also, I am intrigued as to why it has so much power when cold, yet becomes a dog when it warms up.

This change in performance literally happend from one day to the next.. befofre, I had great power, all the time. I did however, have a "miss" that would come and go without any rhyme or reason.

I cannot help but think that I have something electrical going on, any ideas??
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Old 11-29-2007, 05:38 PM
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Join Date: Oct 2007
Location: Greater Metropolitan Beaverdam VA
Posts: 2,107
I had similar problem on my 1988 560SL. Problem was the engine temperature sensor that feeds the fuel injection computer. This sensor is located in the intake manifold, front of engine on the driver side just under the front edge of the air cleaner. The sensor has a green top and two wires attached. You must remove air cleaner to access.
The problem is obviously engine temperature-related. I think you replaced way too much stuff chasing this problem. Let logic and ALLDATA be your guide.

Rough idle may be a separate problem, probably a vacuum leak. There is an intake manifold vacuum outlet on the rear of the engine on the passenger side. My connecting rubber hose was rotted/split there. Replaced and idles smoothly. The clue to that hose being bad is your "economy" indicator. If it does not work or does not go full range, that vacuum connection needs attention. The connection may be found by tracing the vacuum tuble that runs from a 4-way vacuum connector at the driver's side firewall and across the top of the firewall into the intake manifold vacuum outlet.

Last edited by rocky raccoon; 11-29-2007 at 05:49 PM. Reason: add information
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