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Misfire, No DTCs

866 Views 2 Replies 2 Participants Last post by  glitchvdub

I am working on my Girlfriends vehicle and having a bit of trouble diagnosing the issue. I am not to familiar with Mercedes, I have a lot of experience with Volkswagen. I have searched the forums and tried many things from various posts, but I am still experiencing the same issue.

The Vehicle
1996 SL500 US spec with 158xxx miles

My Girlfriend went for her workout the other morning, the car ran fine. An hour later she came out, started the car and it started misfiring and hunting idle. She attempted to drive it and found the power was severely reduced with the misfire making it almost impossible to drive. She got it home and parked it.

  • 0 DTC's stored
  • Spark plugs changed
  • Air filters changed
  • Breather tube found to have a massive hole, Replaced
  • Compression test all cylinders between 140-160, might be a bit low
  • Coil Packs resistance tested between .8-.9, Tested between the outer pins on 200Ω (I have a cheap multimeter if this does not sound correct let me know and I will get a better one to re test.)
  • Crank PS resistance tested at .66, tested on 20kΩ
  • Cam PS I could not get a reading out of, This I bench tested out of the vehicle let me know if I am doing something incorrect
  • fuel filter was replaced within 10K miles

Other Item of Note
I have noticed that the top end ticking has gotten a bit louder, could be just me being a bit more hyper sensitive with this breakdown. I haven't yet pulled the valve covers to check the oilers, I am sure at 158xxx it needs a few replaced.

My Thoughts
I believe I may be dealing with a bad cam sensor, but without it throwing any DTC's I would hate to just start throwing parts at it even if they are fairly cheap.

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My OBDII scanner showed no pending codes, which I found odd. You could tell it was misfiring by the popping, raw fuel smell and liquid coming out of the exhaust.
1 - 2 of 3 Posts
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