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Engine Shakes & Stalls (2003 C-230K)

2K views 6 replies 4 participants last post by  Buellwinkle 
#1 ·
This is my first post. Yesterday, I was sitting at a stop light. The car started shaking. I noticed the RPM needle bouncing up and down to dangerously low levels. Then the car just stalled. It does this now whenever the car is idleing.

I don't know much about cars, but my first guess was something to do with fuel injection, but I may be way off.

Another concern I have is that with gas prices so high, I have been putting 87 octane in for the last 2 years rather than the recommended 91 octane. Could this hurt the car? High octane gas just seems like a racket to me...

Diagnostics are about $100/hour, and it is SOOOO like me to pay for something only to find out that my spark plugs need replacing...does anyone know what this might be...or has anyone had similar issues?

Thanks so much!
 
#2 ·
no to sound mean but do a little research on why you need higher test gas. It has to do with compression levels, preignition and boost...

there are multiple problems that it could be.

valves
plugs
cats
02 sensors
MAS
timing

do you run an oily K&N?
Jake
 
#4 ·
dexter.clampett said:
Another concern I have is that with gas prices so high, I have been putting 87 octane in for the last 2 years rather than the recommended 91 octane. Could this hurt the car? High octane gas just seems like a racket to me...
Dude, don't do that to your car! Your engine runs more efficiently with the proper octane rating, not to mention that you could be destroying your engine incrementally. The savings in gas prices for lower octane fuel are vastly outweighed by the greater fuel efficiency and the savings in repair costs when using the proper octane rating reccommended by the manufacturer. You might also be voiding your warranty, if you still have any. Not sure what the specifics are where you live.

Read: http://www.superchargersonline.com/content.asp?ID=104
 
#5 ·
dexter.clampett said:
I have been putting 87 octane in for the last 2 years rather than the recommended 91 octane. Could this hurt the car? High octane gas just seems like a racket to me...

Thanks so much!
See what happens when you cheap out. For pennies per gallon you can now have thousands of dollars worth of repair. I've seen a dyno where someone used 89 octane and he lost a bunch of power.

But lets see how much money are you willing to invest. The first thing is you'll need an OBD2 scanner or software, find one that will work with MB or make sure you can return it if it doesn't. Your check engine light may not be lit but that doesn't mean there are no pending codes. The likely problem you are having is the CPS (crank position sensor). It's reasonably cheap (as MB sensors go) and easy to install.
 
#6 ·
Buellwinkle said:
But lets see how much money are you willing to invest. The first thing is you'll need an OBD2 scanner or software, find one that will work with MB or make sure you can return it if it doesn't. Your check engine light may not be lit but that doesn't mean there are no pending codes. The likely problem you are having is the CPS (crank position sensor). It's reasonably cheap (as MB sensors go) and easy to install.
Thanks...but I am a broke law student...I hope it is the CPS as you say. So, do you have one of those OBD2 scanners? I live in Irvine (The O.C.)...hook it up! :thumbsup:
 
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