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Registered
1987 560SL
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92 Posts
Discussion Starter #1
Its been almost a year now and I am still chasing that O2 sensor flicker. I always thought it was the OVP relay but as it turns out the relay clicking was the one below the OVP (the one closest to the fuse box as there are three in that area) That relay as it seems cuts off the smog pump and triggers the O2 light. Also I dont know if it is related or not but I had to change the Aux fan relay twice!!
it is worst when the car is cool but still happens at warm temps. SO far I have inspected all wiring, cleaned all connections, changed all the fuses to copper, disconnected the smog pump, changed that clicking relay, cleaned all connections to the temp sensor, idling valve (connected and disconnected all and no effect on that light flicker) the car idles hard when that click and light are on but runs fine otherwise. it died only once. I checked the wiring diagrams and found the vacuum valve and checked that was well and the vacuum seems to be getting in and out with no trouble and the valve is being triggerred appropriately
I am just baffled, any thoughts or ideas??
 

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Registered
1987 560SL
Joined
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92 Posts
Discussion Starter #2
SOLVED!!!

So I chased the voltage and everything was on the spot, then I head to check on the idle valve and removed the air cleaner, to my surprise there was a large puddle of gasoline under it. I cleaned it up and fired up the engine again, behold the main fuel line leaking!!!! Got that fixed and my car is good as new!!!


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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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32,314 Posts
Major catastrophe avoided. Sometimes we forget to start at the beginning with the simple stuff. Thanks.
 

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Registered
1987 560SL
Joined
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92 Posts
Discussion Starter #5
Well I was wrong!!! The o2 gremlin still goes on and off, I finally found the clicking relay, it is the relay just below the ovp labelled 32 with it the idle fluctuates and the O2 lights come on, thoughts!??


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Registered
1987 560SL
Joined
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92 Posts
Discussion Starter #6
SOLVED, again!!!

Yet another update, no fuel leak, no worn wires, new fuses and more and still o2 sensor clicking, disconnecting the O2 sensor had no effect what so ever, so fed up with all that and since the ECM is the only thing left, I bought one off eBay and installed it and viola, problem solved!!! The ECM was giving wrong messages somehow and was messing up a whole bunch of things, the smog pump operation, the idle, the O2 sensor light

Any way I hope this helps anyone who has the same issue


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