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Hello!

Bought my R170 a few months ago and it has ran like an absolute turd ever since I got it (106K miles). I have always had problems with a rough idle, where it starts at around 1500RMP then calms down to normal after a few minutes. It jerks back when moving in reverse, then runs overall sluggishly and like its under load most of the time when in drive. Originally, the car would stall out completely. I replaced the battery, K40 Relay, and Crankshaft position sensor. Afterwards, car runs somewhat better for a couple weeks. Now, while the engine doesnt stall, when stopped or driving slowly, the car will occasionally lose acceleration. I can lay down on the pedal and the car will most of the time cruise at around 20mph until I can pull over. At this time, the engine is roaring, and feels like its going to jump out of the engine bay. Even when holding down on the brake, the car will sputter and jump, almost to the point where it is able to overpower the brakes and inch forward. Usually I can shut the engine off for a moment, restart, and itll drive relatively okay for the rest of the way back home.

Ive cleaned the MAF sensor, replaced the CPS and K40, and have 0 CEL lights for the issue. The only lights are for my BAS ASR, which is related to the brake pump. Im at an absolute loss as to where to even start repairing this thing. I don't want to go and throw hundreds of dollars at random parts until I have a half a new engine to find out the fix. Right now I'm looking at replacing the spark plugs, ignition coils, and fuel filter, but honestly I have no idea where to even start with this thing.
 

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1998 , SLK 230
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225 Posts
If you don't know the history of the spark plugs and filter, I'd change them anyway as a routine service item and see what happens.
 

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2002 SLK230
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594 Posts
Sounds like you have a leak in the pressurized air coming off the SC. Track it's path to make sure no clamps have broken nor any tubes cracked.


You also need to look at the wiring harness as it goes to the cam sensor.....they can be fouled with oil and screw up everything!

jeff
 

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Registered
1998 , SLK 230
Joined
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225 Posts
Sounds like you have a leak in the pressurized air coming off the SC. Track it's path to make sure no clamps have broken nor any tubes cracked.


You also need to look at the wiring harness as it goes to the cam sensor.....they can be fouled with oil and screw up everything!

jeff
Stubby has posted here somewhere directions for making a test rig to find supercharger leaks.
I had a leak from the small line on the RH front of the engine ( can't remember what it does) . Fixing it regained a huge amount of power.
 
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