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Old 11-30-2007, 07:32 AM
rocky raccoon rocky raccoon is online now
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Join Date: Oct 2007
Location: Greater Metropolitan Beaverdam VA
Posts: 2,518
1988 560SL rough idle repair report

Symptoms: 1988 560SL starts and runs good but has a rough idle. "Economy" indicator not working, driver's door power lock not working (all other power locks o.k.), footwell heater door shutter will not open.

Fault Isolation: This is a classic vacuum leak problem. Symptoms are limited to a leak common to the driver's door, dashboard indicator and possibly heater controls. The inoperative Economy indicator is your easiest clue. Refer to ALLDATA for component locations. In engine compartment at driver's side firewall there is a 4-way vacuum connector with 3 lines leading through the firewall. Since the faults are multiple and one of them is the driver's door, the problem should lie in the vacuum source line to that connector. Traced that line across top of firewall to a vacuum outlet connector on rear of intake manifold left (passenger) side. My flexible connector tube was rotted and split at that connection.

Repair: Replaced the flexible connector tube using thick wall plastic tubing. Space is limited between the connector and the firewall and you must reach through the fuel injector linkage. Tiny little hands and/or a lot of patience are your best tools.

Result: Smooth idle, Economy indicator works and driver's door power locks. The footwell heater flaps now work sometimes but are still squirrely. I have other problems there.
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