Misfie on 5 cyl M278 check engine sometimes
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GL500
Misfie on 5 cyl M278 check engine sometimes
hello I have a problem with misfire on cylinder 5 it happens only on idle. The car drives very well sometimes the error goes out. On cylinder 5 it makes fuel corrections.
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From: New Zealand
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GL500
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From: Melbourne, Australia
2010 ML550 VIN WDC1641722A564750, 2010 B180
You scanned it to reveal cylinder No. 5? Try swapping the coil and spark plug with another one and see if it the fault follows it to the other cylinder.
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13 gl550
My suggestion is to buy a usb bore scope camera from amazon for like $20. Remove the #5 spark plug, should take all of 10 minutes to remove the airbox, the rubber thingy, coilpack and then the plug. Put the scope down into the bore and inspect for scoring. Its a VERY common problem for our engines that poor oil maintenance and a poor aluminum cylinder coating causes the piston/rings to eat the side of the cylinder. The only solution is pulling the block and sending it to be sleeved, which for me has been almost unpossible. Theres a guy here that does one a year and Ive found a couple race engine mercedes/posrche shops that do it for like $10000. The other solution would be to buy a used engine from like ebay and swap it in, cross your fingers, sell the car and buy something with a more reliable engine. Unfortunately this is the demise of the entire x166 m278 platform.
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From: Gresham, OR
GL450
For me, removing the #5 coil was difficult because I was trying to save the coil. 10 mins? Only if you've done it before and are very experienced and it's been taken apart recently and nothing is stuck. It took me more that 10 min just to watch a couple Youtube videos about it before I even started. I did it a couple weeks ago on my 140k mile 2013 GL450 and even with all the tools and tricks (wire wrapped around it, etc etc) I read about, it the coil boot would not come loose from the plug (probably had been on the plug for 12 years). After trying for more than an hour, I had to cut the coil to get it off. All the tubing and pipes next to the #5 cylinder make access a pain. And even removing the airbox and its rear connector and hoses is difficult on my M278, things are stuck and break if you pull too hard. Maybe you can do it in 10 min, but I couldn't and I've changed plugs and coils on other cars before. I put my borescope into the cylinder and as I expected mine is scored, I'm getting a bad noise from the engine but no codes . . yet. I replaced all my plugs (they were oily) and the #5 coil that I cut. Mine had been feeling sluggish before, and the new plugs and coil helped restore power but the bad sound and scoring are still there. I recommend that you replace the plug and coil, don't bother with the swapping to other cylinders, reassembling and testing then disassembling and moving the coils, you're likely to break a coil with all the swapping. You have a code and know it's #5 and it's the common failure point for these engines, if you've done the work to disassemble it all and take it off, might as well put a new plug and coil on there.
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