1996 c280 sport with high tickover

rob the painter

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Greetings all. I was just wondering if anyone can help me.

My c280 straight six ticks over at around 1500- 1800 rpm when the engine is warm. First thing in the morning when cold, the tickover is under 1000 rpm as it should be under normal conditions.

I removed the throttle body, cleaned it with carb cleaner, inspected it (I noticed an adjustable 'stop' inside the mechanism so maybe it can be re- caliburated?) and built it back up using grease on the original gasket as it looked serviceable. I also replaced the MAF meter.

After doing this the car went into limp home mode. I took it to the garage for a scan but it seemed to cure itself. It was MOT'd, passed, but played up again reversing off the ramp. The mechanic ran a fault code read but it gave confusing readings. He also said there was low voltage at the ECU. It now drives fine as you would expect, save the high tickover.

I have a feeling it may be the coolant temperature sensor, as there is a smell of fuel, suggesting it may be running rich. Sadly I can't seem to find it. I can only see the coolant sensor (4 pin plug) which, when removed with the engine running, only disconnects the guage (so I assume thats not the ecu sensor).

I would be grateful if anyone can offer any advice. It would be a pleasure to drive if it would run right.

Kind regards, Rob.
 
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rob the painter

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coalville, leicestershire
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Touch wood,I think she's cured. There is a relay near the ecu that had a loose coil which was arcing out on the relay body. One careful blob of solder later and she ticks over like it should.
 

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