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1987 230E silver W124 (sold). 1991 W140 400SEL silver.C280 W202 Silver (RIP) 2006 W203 C220 CDI
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100 Posts
Discussion Starter #1
The story so far;
For several weeks before the event, the car had an occasional miss, noticeable only when at idle.

Other than that, the car was performing flawlessly, and would easily do 0-100kmh in 6 seconds.

Serviced every 10,000km as per advice from MB, along with tyre rotation.

Then;
The missing issue came more pronounced, especially with a loss of power on acceleration, causing a bit of stress at intersections!

On Christmas eve, en route to Benalla, the car lost power dramatically, to the extent that the car was flat to the floor to maintain 100kmh, and using over 20 litres/100Km. This was later measured to be 35L/100Km. She is running VERY rich.

The car was trucked by RACV to MB Shepparton, where the fault was diagnosed as a faulty Air Mass sensor. At the same inspection, it was noted the wiring harness was cracking in places. Most noticeably a 3cm section on the passenger side underneath the main air intake.

A replacement MAF was sought and installed as advised.

However, the lack of performance remained the same. The MAF was turned partially in its mount, about 1cm clockwise as seen from above, and the performance improved – slightly. But now was not idling properly, and would stall when the AC was on.

AS MB Shepparton were overbooked for several weeks, the car was driven to MB specialist Hans Stephan in Shepparton, who performed a computer diagnosis that revealed the only issue was the idle contact switch.

This would explain the new problem of idling. However, the other diagnosis tests passed everything including the MAF, air inlet temp and O2 sensor, which would indicate the MAF was working correctly.

After the computer section was completed, the number 6 spark plug was removed and showed signs of rich running, with a very slight overgap. An examination of service records indicate a plug change is due, but other than that, they are working.

That’s where things stand at the moment. She is still running rough, and very rich... around 30L/100Km with NO performance whatsoever.

Over to you.
 

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Registered
1987 230E silver W124 (sold). 1991 W140 400SEL silver.C280 W202 Silver (RIP) 2006 W203 C220 CDI
Joined
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100 Posts
Discussion Starter #2
Okay,
Three months down the track and the car is FINALLY back on the road.....

To cut a long story short,
* the smoke was diagnosed as being blowback from an over full gearbox (at last service)
* MB star machine diagnosis was faulty engine loom and MAF ($3500)
* Loom and MAF replaced. Im walking with a limp due to hip pocket injury.

Performance STILL next to nil. Running super rich, STILL about 35L/100km. It was the same as before, other than the smoke had cleared...

Contacted mechanic friend who popped over, and suggested I take the car to Wharfside Motors in Echuca. Thery are fuel injection specialists and auto engineers.

* Fault diagnosed as ignition (He took less than ten seconds after driving it, and about two seconds to confirm his theory once he lifted the bonnet)
* Fault traced to driver side rotor button.. Multiple short circuits and a crack or three.




* Passenger side rotor button checked and cleaned. OK and within tolerance.
* Replacement part ordered and arrived TWO days later.
* Part installed and plugs checked. Gaps within tolerance according to spec. Fouling due to fuel buildup (no spark remember?)
* Car taken for a run, and plugs examined; clearing up.

* Car delivered to me... in perfect bloody working order...

Cost; $350. of which the part was $150.

Wasted cost; $3500 for a new loom and MAF.


Moral of the story according to the Mechanic was not to trust the STAR Machine for a complete diagnosis. Always start with the basics and work UP.

Anyone want a loom and MAF? ;)
 

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1993 300SEL (Sold) 2007 X5
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7,218 Posts
Well if your harness is cracking you need to replace it anyway - actually looking at your original post I would have suggested caps and rotors as I had a similar issue - seems I missed this thread along with everyone else.
 
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