Fuel System Service, what parts to change while in there

ruben356 · 02-28-2022, 05:32 PM

Hey all, recently did plugs and coils on my car, 13 at 67k. Plugs had been done at 37k so right at the point they needed to be redone, coils where OEM, but for good measure replaced them all.

I began getting slight rough idle, with 2 cylinder misfires which prompted me to do them now. Car runs great, not breaking up at WOT and no Drivetrain Malfunction. Just the check engine light keeps coming on and still slight rough idle, always same cylinder misfires (8&6) before the service i was getting constant 8&5 misfires.

As preventative maintenance, I will also be replacing all 8 injectors, as they are OEM, and I know the early EU5's were failure prone. Some of the plugs were a bit fouled but nothing alarming, indicating possibly carbon buildup starting. I use a fuel system cleaner every few fill-ups, but the car is almost 9 years old.

Just wondering what other parts should i replace while doing the injectors. Should i do the High/Low pressure sensors, Fuel filter, HPFP's? Anything else maybe im missing? I have not had any issues with drivetrain malfunction leading me to believe the HPFP's or the tank pump are bad or going bad, so I am thinkin maybe just do the injectors and High/Low sensors.

TinCanSailor · 03-04-2022, 10:05 AM

Injectors are on my to do list for sure. Did you replace the MAF's yet? I'd also look around to make sure the engine isn't getting unmetered air in and do a compression check at least on the cylinders that misfired.

ruben356 · 03-07-2022, 12:13 AM

I have been seeing a lot of people mention MAFS, i will be cleaning them out, as i did notice a bit of residue last time i changed my intake filters, even if the issue is resolved after the injectors. Took it to shop to properly troubleshoot, they found multiple injectors beginning to cut fuel slightly which indicates incoming failures. Seems all my injectors were OEM no record of any failing or being replaced. So i just decided to have the replace all with brand new Bosch injectors and decouplers. Shop did not mention needing compression test.

02-28-2022, 05:32 PM	#1
ruben356 Private First Class 91 Rep 174 Posts Drives: F13 M6 _ San Marino Blue Join Date: Feb 2017 Location: NJ iTrader: (0)	Fuel System Service, what parts to change while in there Hey all, recently did plugs and coils on my car, 13 at 67k. Plugs had been done at 37k so right at the point they needed to be redone, coils where OEM, but for good measure replaced them all. I began getting slight rough idle, with 2 cylinder misfires which prompted me to do them now. Car runs great, not breaking up at WOT and no Drivetrain Malfunction. Just the check engine light keeps coming on and still slight rough idle, always same cylinder misfires (8&6) before the service i was getting constant 8&5 misfires. As preventative maintenance, I will also be replacing all 8 injectors, as they are OEM, and I know the early EU5's were failure prone. Some of the plugs were a bit fouled but nothing alarming, indicating possibly carbon buildup starting. I use a fuel system cleaner every few fill-ups, but the car is almost 9 years old. Just wondering what other parts should i replace while doing the injectors. Should i do the High/Low pressure sensors, Fuel filter, HPFP's? Anything else maybe im missing? I have not had any issues with drivetrain malfunction leading me to believe the HPFP's or the tank pump are bad or going bad, so I am thinkin maybe just do the injectors and High/Low sensors.
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03-04-2022, 10:05 AM	#2
TinCanSailor Fueled by Recycled Dinosaurs! 630 Rep 1,170 Posts Drives: F06 M6 Join Date: Dec 2019 Location: 813Bay, Fl iTrader: (2) Garage List 2015 BMW M6 Gran Coupe [9.75]	Injectors are on my to do list for sure. Did you replace the MAF's yet? I'd also look around to make sure the engine isn't getting unmetered air in and do a compression check at least on the cylinders that misfired. __________________ 2015 F06 M6 Silverstone Metallic II, Individual Full Leather, B&O, Night Vis, CCB, RKAutowerks (CP Rods/Pistons, DI Cams, CF Intakes, Coated DP's & Billet Diff Brace), InfinityAuto Turbo Inlets, Mishi Oil Cooler, JB4, XHP S3, BM S3
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03-07-2022, 12:13 AM	#3
ruben356 Private First Class 91 Rep 174 Posts Drives: F13 M6 _ San Marino Blue Join Date: Feb 2017 Location: NJ iTrader: (0)	I have been seeing a lot of people mention MAFS, i will be cleaning them out, as i did notice a bit of residue last time i changed my intake filters, even if the issue is resolved after the injectors. Took it to shop to properly troubleshoot, they found multiple injectors beginning to cut fuel slightly which indicates incoming failures. Seems all my injectors were OEM no record of any failing or being replaced. So i just decided to have the replace all with brand new Bosch injectors and decouplers. Shop did not mention needing compression test.
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