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If it's not one thing it's another. Ok, Got the car running again after the no start/no power episode. Even before this, the car was shaking and misfiring in idle and in drive. A scan code (P030500) revealed Cylinder 5 was the culprit. Pulled spark plug for that cylinder was black with carbon build up. New spark plug and ignition coil #5 was switched with cylinder 4. Scan still revealed Cylinder 5 as the lone misfire. Used CRC GDI cleaner as directed but even when the gas is floored it will only go to about 2700 RPM then settles back down to 2000. I'm thinking that if the problem was the fuel rail there would be misfires on more than one cylinder. Perhaps a bad fuel injector on Cylinder 5? A worse scenario would be a leaking piston. As a sidenote, the ECU was unplugged, contacts cleaned and reconnected. The car ran fine for about 60 seconds ..then back to misfiring. Any suggestions? 2015 E400 RWD W207 Coupe. M276 DE LA 30 twin turbo engine.
Last edited by Paul Shalom; Sep 7, 2020 at 12:39 AM.
Thank you. I'll put that first on a list of priority checks. The mechanic says it is idling far better now with Very little shaking. I'm thinking even though we could not use the CRC cleaner as intended it still, eventually made an improvement.
Update: It is now going above 4000 RPM in park. I guess the CRC GDI cleaner did some work even though we weren't able to drive it full out an hour after applying the CRC. It's also shaking much less. I'm more confident that it is just a bad fuel injector on cylinder #5 now. We're going to do a compression test and cylinder balance test today with the Autel MK808 scanner.
