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#1
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High idle problem - overload relay?
I have an '82 380SL. It is idling at about 1200 in neutral, 900 in gear. I have already replaced both the idle control unit and the valve - no difference. It also surges the idle rythmically when in neutral.
When I pull the overload protection relay out while running, the engine idles normally (750 in neutral (no surging), 600 in gear). The fuse on it is not blown. I put it back in and it starts misbehaving again. My guess is: bad overload protection relay; replace it. Any other ideas? Thanks, John |
#2
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Strange
I don't see what a new OVP would do for you in this situation. When you pull the OVP, you go back to manual control of both the idle and the mixture (because the OVP also supplies power to the lambda system).
My suspicion is that you may have some or all of three problems. - bad temp sensor (back of right head) keeping the idle high in warm-up mode even when hot. Try pulling the connector and bridging the contacts. You should see an idle increase with a hot engine. - lazy O2 sensor or slightly lean mixure causing over-correction. Put an old fashioned dwell meter on pin 3 of the diag socket and see if the on/off ratio matches the surging of the idle. - vacuum or air leaks
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Chuck Taylor Falls Church VA '66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe |
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