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'01 SLK230 Kompressor, '95 C280, '98 BMW 528i, '86 BMW M635CSi EURO, '87 190E 2.3-16
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441 Posts
Discussion Starter · #1 ·
Doing around 90 mph on the highway car suddenly hits the "wall". Feels like no boost, struggling to go over 80.
Next day it "cured" itself, but only for the duration of that day.
Car also warms up differently now.

My MAF is clean, clutch is good, supercharger is in working order, all intake from filter to throttle is undamaged, engine idles perfect. Car has 82 kmi, well taken care of.

I have a suspicion that the the bypass flap (don't know the name of it) located on top of supercharger stopped working properly and stays open all the time so there's no boost.

I've checked it (took it apart, gave 12 to motor) and it works fine. It does make noise with ignition on, but does not react to the gas pedal (I had the intake partially apart when I tested it).

It has 5 wires at the plug with 2 of them connected to mysterious sensor under the plastic engine cover, on top of intake manifold (air temp sensor?).

Anyway, I was wondering if anybody experienced the same and can shed some light on the issue.

Thanks in advance!
 

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Two 1998 SLK230s, 2003 SLK230 SE, 2002 ML320
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920 Posts
Any codes? I had loss of boost on a '98 SLK (not quite the same as yours). It was a faulty camshaft advance sensor which would go open circuit (faulty) when the engine got up to temperature. The ECU inhibited the supercharger under that condition to protect the engine.
It's worth checking for codes and also live data on Carsoft to see what the ECU thinks is happening.
 

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'01 SLK230 Kompressor, '95 C280, '98 BMW 528i, '86 BMW M635CSi EURO, '87 190E 2.3-16
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441 Posts
Discussion Starter · #3 ·
Read the codes - "Turbocharger Wastegate Solenoid", I was right.

I took it apart again, the motor part looks ok inside, brushes are not worn.
In case it was just dirty brushes that caused it to draw too much juice and made ECU shut it down (another theory), I've cleaned them and cleared the codes.

Not sure if it's gonna help, but worth a try I guess...
 

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2002 SLK 32 AMG 1997 SLK230 & 1978 280CE
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377 Posts
Attached is an excellent article on SLK boost control.....

.....control of the Air Bypass Valve is via a PWM (Pulse Width Modulation) signal

.....best check is to look for any sign of movement of the bypass butterfly when you 'gun' the throttle in neutral with hose disconnected

.....a diagnostic boost gauge will give you the best indication of what is going on.....have a good look at all your inlet ducting to make sure there is nothing undone or leaking

....you will have no boost if the ABV is not working correctly......but quite a few things can cause the ECU to think the ABV is malfunctioning and switch off the boost.........faulty MAF is a common cause....another is a boost leak

Please post the actual DTC Code.....???P0243 or???P0803 and any other (including pending) codes...

Cheers

David
 

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Registered
'01 SLK230 Kompressor, '95 C280, '98 BMW 528i, '86 BMW M635CSi EURO, '87 190E 2.3-16
Joined
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441 Posts
Discussion Starter · #5 ·
Thanks a lot!
So far ABV works ok. I'll post the code if it pops up.
As I mentioned before, I have checked the intake all the way to the throttle, there are no leaks.
 

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'01 SLK230 Kompressor, '95 C280, '98 BMW 528i, '86 BMW M635CSi EURO, '87 190E 2.3-16
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441 Posts
Discussion Starter · #6 ·
Ok, one week after brushes were cleaned the problem has not reappeared (did around 300 miles), so I guess that was it.
 
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